1a On capitula => 21

1b On vegetative parts => 2

2a Galls less than 1 mm long or with fruiting fungi on the surface => 15

2b Other kinds of malformations caused by animals (or bacteria) => 3

3a Malformations mainly on leaves => 8

3b Galls at the top of main- and lateral shoots or on stems => 4

4a Terminally on plants the growth of which is not stunted => 6

4b Swellings of lower stem parts => 5

5a Stem with considerable, one-sided, ± blistered, smooth-walled, unilocular swelling, Larva without head capsule or legs. Bellidiastrum michelii: Tephritis arnicae

5b Spongy, pale, often massive stem galls with rugose surface. “Aster”: Ditylenchus dipsaci

5c Stem base, still above the underground root collar, swollen; in other areas one-sided, oval, about 10–12 mm long, 3 mm wide; almost on all sides of the thin stems. A yellow caterpillar up to 10 mm with a yellow-brown head capsule. Galetella linosyris: Caulastrocecis furfurella

= Root cankers, caused by Agrobacterium tumefaciens, and “leafy galls” of Rhodococcus fascians have been reported

6a Malformations without conspicuous swellings of the stem => 7

6b Plant growth stunted in longitudinal direction, shoot tip swollen, curved and reddened. One caterpillar. Galetella linosyris, Tripolium pannonicum subsp. tripolium: Eucosma aspidiscana

6c Very conspicuous swelling of twig, containing one caterpillar. Galetella sedifolia: Caulastrocecis gypsella

7a Shoot stem shortened. Abnormal twig- and leaf development on long- or short shoots. Galetella linosyris: Aceria linosyrina

7b On the stunted shoots a rotund gall encased by several leaves, up to 10 mm long, greenish. Larvae between the inner leaves. A. alpinus: Rhopalomyia astericola

8a Leaf blade rolled, folded or curled => 11

8b Leaves with local, ± constant shaped, galls => 9

9a Galls glabrous => 10

9b Whitish pubescent, rotund, spongy, uni- or multilocular galls, up to 16 mm long, yellowish, often many on ± stunted plants, mainly close to basal leaves, more rarely on stem leaves or even on the scales of the capitula. A. alpinus: Unidentified gall midge

10a Leaf blade with greenish-yellow galls, 3–5 mm long, bulging on the underside, about 1.5 mm thick, ± spindle-shaped; often spreading from midrib and occupying or even surmounting the whole leaf blade; sometimes several per leaf, occasionally coalescing. One dark orange-yellow larva per gall. On Galatella linosyris; Tripolium pannonicum: Dasineura linosyridis

10b Cylindrical, up to 20 mm long, 5 mm wide, very thick-walled, tough, multilocular, tubercular gall on leaf base, including the midrib. The upper leaf part folded along the midrib. Tripolium pannonicum: Inducer unidentified – ? gall wasp

11a Leaf blade curved and curled by aphids or cercopids => 14

11b Leaf blade folded or rolled; midge- or mite galls => 12

12a Leaf margin rolled => 13

12b Leaf blade folded downwards, ± bleached. Galatella linosyris: Unidentified gall midge

13a Leaf margin upwardly curved or folded, thickened and bleached. Larvae on upper side. A. alpinus: Unidentified gall midge

13b Leaf blade with loose, weakly thickened leaf margin roll without abnormal pubescence. Bellidiastrum michelii: Aceria opistholia

14a Leaf blade at the margins downwardly curved or rolled, ± strongly curled. Sometimes several leaves densely bunched at the compressed shoot tips. Aphids on the underside. A. amellus and cultivated forms, Bellidiastrum michelii, Tripolium: Brachycaudus helichrysi

14b Leaves, depending on their condition, differently ± strongly curved downwards and curled. Tissue close to the froth-covered nymph dark green. Sometimes several leaves converging spoon- or clump-like on compressed, ± curved stems. A. amellus, Symphiotrichum novae-angliae, novi-belgii including the cultivated forms, S. lanceolatum, Tripolium, etc.: Philaenus spumarius

15a Fungus, infected area larger than 1 mm => 16

15b Many golden-yellow warts, hardly 1 mm long, mainly on the underside of basal leaves. Bellidiastrum michelii: Synchytrium aureum

16a Minor swellings, occupied by brown-black telia => 19

16b Sporangia containing aecia => 17

17a On Bellidiastrum michelii, Tripolium => 18

17b On Galatella linosyris. Sporangia mainly on the underside of the leaves, yellowish, hardly swollen, sometimes bulging the leaf out laterally; also indistinctly swollen callus on the stems about 5–7 mm long: Puccinia linosyridis-caricis

18a On Tripolium. Sori on leaves and stem hardly cecidogenic. Visible malformations only reported laterally on the base of the capitula slightly swollen, ± bent flower head buds. Puccinia extensicola

18b On A. bellidiastrum, hardly cecidogenic aecia: Puccinia firma

19a On A. alpinus, Bellidiastrum michelii => 20

19b On other asters. Sori on the leaf veins or stem parts rotund-oval to spindle-shaped, on sometimes slightly swollen pads. A. amellus, Galatella linosyris, Tripolium, etc.: Puccinia cnici-oleracei

20a Similar sori on A. alpinus: Puccinia asteris-alpini

20b Sori usually in converging, callus-like groups on curved petioles and leaf veins; occasionally on rotund, usually violet-red bordered pads on the leaf undersides. Bellidiastrum michelii: Puccinia bellidiastri

21a Capitula deformed. Receptacle swollen, all- or one-sided. Larvae in receptacle, cylindrically shaped, with black mandibles => 22

21b Capitula hardly swollen. Larvae without conspicuous mouth parts, between flowers. Galatella linosyris: Dasineura procera

= In capitula of Bellidiastrum michelii midge larvae of an undescribed Dasineura have been mentioned.

21c Florets forming a compact rosette of green leaves (phyllanthy); contains mites with four pairs of legs. Symphyotrichum novi-belgii: Phytonemus pallidus

22a Galls preferentially when unilaterally affected ± bent downwards; marginal flowers partially not developed. Tripolium: Campiglossa plantaginis

22b Similar malformations Tripolium: Trupanea stellata

22c In Germany, J. Haase collected inflorescences of Tripolium with many widely extending capitula, of which the flowers were largely reduced and deformed. Cause unknown; similar malformations also known from other Asteraceae, especially Liguliflorae and Cynareae. Might be caused by viruses.

1a On buds, leaves, inflorescences or fruits => 6

1b On axial parts of shoot => 2

1c Root with rounded or spindle-shaped swelling, 2–5 mm across; containing eelworms, some may be glistening white pear-shaped females with eggs: Meloidogyne ardenensis

2a On thicker stems and branches => 4

2b On younger twigs => 3

3a Shoot axis with irregular rimmed depressions, containing the causer under a pear-shaped scale, about 2.5–3 mm long. F. excelsior: Chionaspis salicis

3b Younger shoots with cauliflower-like proliferations, about 5–20 mm across. F. americana, angustifolia, excelsior, ornus: Aceria fraxinivora

4a Malformations caused by inconspicuous parasites invisible from the outside or on younger stems or thicker branches => 5

4b Thicker axial parts with spindle-, club-shaped, or nodular swellings bearing: Viscum album

5a Proliferations develop, mainly on nodes, usually closed, rotund, at first glabrous, later on cracked and ruptured, up to about 30 mm long, later on discoloured brown to black. “Bacterial cancer”. F. excelsior: Pseudomonas savastanoi pv. fraxini

= In many areas similar proliferations due to Agrobacterium tumefaciens have been reported.

= So-called bark roses on ash, rather similar proliferations, should not be confused with previous malformations. They occur mainly on thicker axial parts and differ from basally usually distinctly narrowed bacterial cancer by being broadly attached to the host. These proliferations, often cracked, ± rosette-like are responses to wounds caused by feeding of the scolytid beetle Hylesinus fraxini.

5b Open cancer, mainly on branches, usually arranged according to the bearing organ, provided with conspicuously glabrous to warty rims surrounded to varied extent; perennial. “Nectria-cancer”. F. excelsior: cf. Neonectria ditissima

= Apparent “cancers” on ash are often caused by freezing and not by parasites

6a On buds or leaves => 8

6b On inflorescences or fruits => 7

7a Fruit irregularly slightly swollen; gall surface usually strongly undulate, becoming brown and cracked. Containing several to many lemon-yellow larvae. F. excelsior, ornus: Contarinia marchali

7b Inflorescences transformed into at first green, soon browned, tuberculate, cauliflower-like masses. Flower peduncles disfigured, ± cauliflower-like distorted. “Klunkern” in German. F. excelsior, ornus, etc. Aceria fraxinivora

8a On leaves => 9

8b Buds disfigured, scales of buds soon dropping. F. excelsior: Unidentified gall mite

9a Galls confined to single leaves or parts of leaves => 12

9b Malformations extend to several leaves => 10

10a Nest-like clustering of disfigured leaves on shoot tip, caused by aphids => 11

10b Some, usually laterally inserted leaves ± converging, nest-like. Leaf blades curled. Deeper green at site of infestation. Containing a froth-covered nymph. F. excelsior: Philaenus spumarius

11a Petioles, as well as -midrib, severely stunted and distorted, densely clustered. Aphid mainly on midrib and leaf underside, also in much lower numbers on shoot axis. F. angustifolia incl. subsp. oxycarpa; excelsior: Prociphilus fraxini

11b More loosely arranged clustered leaves; aphids mainly on shoot axis and petioles. F. angustifolia, excelsior, mandshurica, pennsylvanica: Prociphilus bumeliae

12a Galls on leaf midrib or -blade => 15

12b Roll of leaf margin => 13

13a Expanded, loose, greenish or pale, partially reddish discoloured, soft to brittle downward rolls => 14

13b Very narrow, cartilaginous downward roll of leaf margin; the rolls are abnormally haired inside. F. angustifolia, excelsior: Aculus fraxini

14a Loose, usually normal, rarely ± pale-green discoloured, soft rolls of leaf margin; containing several midge larvae. F. excelsior: Unidentified gall midge

14b Bladder-like swollen, loose ± thickened roll of leaf margin; brittle, largely discoloured, often with reddish or violet marbling; caused by white-woolly psyllids. F. angustifolia incl. subsp. oxycarpa; excelsior: Psyllopsis fraxini

14c In similar galls also lives Psyllopsis discrepans

14d Leaf roll gall with shallow depression, discoloured bulge above. F. angustifolia incl. subsp. oxycarpa, excelsior, ornus: Psyllopsis fraxinicola

15a Galls on leaf blades, without particular involvement of venation => 17

15b Galls on leaf midrib or leaf veins => 16

16a Leaflets along midrib folded upwards, pod-like, strongly thickened and hardened. Leaf blade not developed or only as a narrow rim. Often all leaflets infected on young leaves. Containing several white larvae with bluish-green gut. F. angustifolia incl. subsp. oxycarpa, americana, excelsior, ornus, pallisiae: Dasineura acrophila

= The yellowish larvae of Contarinia invocata occur as inquilines of D. acrophila as well as the whitish, never greenish translucent larvae of Macrolabis pavida. Reddish-yellow larvae of Clinodiplosis botularia also occur in these galls

16b From similar galls on F. ornus: Trigonodiplosis fraxini

16c On leaf underside bulging, sometimes reddish discoloured pouches on midrib of leaflets, also on midrib and sometimes on petioles, up to 30 (50) mm long. Later with distinctly protruding longitudinal slit on upperside, surrounded by a stronger pubescent rim; often many galls per leaf blade. Each containing a single orange-coloured larva. F. angustifolia incl. subsp. oxycarpa, excelsior, ornus: Dasineura fraxini

17a Variously shaped small grooves, protrusions or pubescence of leaf blade => 20

17b Warts, nodules or parenchyma galls, mostly of constant shape => 18

18a Wart-like or nodular galls => 19

18b Pustule-shaped flat parenchyma galls, hardly 1 mm high, especially protruding on underside with margin, at first red-violet or pale-green, later on brown, up to 8 mm wide. Containing a single yellowish-white larva with green translucent gut. F. angustifolia incl. subsp. oxycarpa, excelsior: Dasineura fraxinea

19a Golden-yellow translucent warts on underside of basal leaves of seedlings, 1 mm across. F. excelsior: Synchytrium aureum

19b Corniculate, or ± hemispherical nodules, up to 1.5 mm high, glabrous, yellowish or reddish, protruding more strongly on one side of leaf. The irregular glabrous tunnels inside the galls usually open on leaf underside. Galls occasionally on leaf midrib and -stalks. F angustifolia, excelsior, ornus: Aceria fraxinicola

20a Flat, irregular, 1–2 mm long, sometimes coalescing yellowish protrusions on upperside of leaf blade, often soon ± browned. F. angustifolia subsp. oxycarpa, excelsior, ornus, pennsylvanica: Aculus epiphyllus

20b Abnormal, at first reddish, then ± brownish pubescence on underside of leaflets, especially along midrib. Hairs multi-cellular, with acuminate or obtuse tip. F. excelsior, ornus, angustifolia subsp. oxycarpa: Aculus epiphyllus

1a On above-ground parts => 4

1b On roots => 2

2a Roots with conspicuous, localised swellings, a few mm long => 3

2b Roots stunted in longitudinal growth, branched bush-like (“hunger roots”). In many cases weakly thickened, sometimes bent, usually darker coloured; inside giant cells. From mid-June onwards with lemon-shaped, at first milky-white, later on brown, soon dropping cysts. Above-ground parts severely stunted. A. fatua, sativa: Heterodera avenae

3a Root tips or young roots swollen and curved. Tissue without particular cavities, containing roundly swollen, immobile eelworms; formation of adventitious roots increased. A. sativa: Meloidogyne cf. artiellia

0b Roots with slender, screw-like bent swellings; inside distinct cavities; containing a few vivid eelworms. Avena spp.: Subanguina radicicola

4a On inflorescences or flowers => 13

4b On vegetative parts => 5

5a On plants with at most rudiments of panicles => 9

5b On plants developing- or with panicles => 6

6a Malformations of stem caused by fly- or midge larvae => 7

6b Leaf sheaths inflated, discoloured. Leaf blade twisted and rolled inwards. Development of panicles often soon stunted, sometimes bleached later on. A. barbata, fatua, sativa incl. ssp. orientalis, strigosa, sterilis: Rhopalosiphum padi

6c Similar, but hardly gall-like malformations may be caused by the following aphids: Sitobion avenae, S. fragariae and Sipha maydis

7a Larvae living between stem and leaf sheaths, without legs, but with sternal spatula => 8

7b Stem stunted at base of the inflorescence, ± slightly swollen. Panicles occasionally severely stunted, often bleached. Larvae feeding on the developing seeds. A. fatua, sativa: Oscinella frit

7c Long conspicuous stripes on chlorotic leaf tissue caused by rust fungus. A. caryophyllea: Puccinia striiformis

8a Stem above a node ± slender, swollen, onion-like, sometimes bent. Under the leaf sheath are several 3–4 (5) mm long, vitreous to greenish-white larvae with arrow-shaped sternal spatula. Caudal part conically tapering. The larva develops into a flattened, flax seed-like, glossy brown puparium. A. fatua, sativa: Mayetiola avenae

8b Stem below the slightly swollen sheaths with several 10–15 mm long, elongated, saddle-shaped depressions, apically rimmed; each gall contains a blood red larva. A. sativa: Haplodiplosis marginata

8c On A. sativa and A. fatua, a similar, but not saddle-shaped swollen, expanded, blackened depressions of the culm, covered by the leaf sheath are possibly induced by Hybolasioptera fasciata

9a Plants usually excessively leafy, ± distinctly swollen at base => 10

9b Leaves of young plants slightly thickened, ± rolled inwards or folded. A. sativa: Anguina tritici

10a Shoots shortened, swollen at base, plants usually excessively leafy. Leaves usually not or only slightly discoloured => 12

10b Shoots shortened, usually less distinctly swollen, at least the inner leaves yellowed; often surmounted by additionally developing, uninfected new shoots => 11

11a Inner leaves yellowed and withered, the outer ones green, central part destroyed; shoot slightly swollen. New shoots often similarly affected, bushy clustered, later surmounted by healthy shoots. Inside is an at first vitreous, then yellowish-white cylindrical maggot, about 3–4 (5) mm long, provided with mandibles [buccal hooks] and tunneling into the root neck; with 2 caudal cone-like spiracles; pupa pale brown. A. fatua, sativa: Oscinella frit

11b Infected shoots usually sessile, at base sometimes slightly thickened. Plants usually very leafy, with many shoots which also become infected later on; leaves yellowing, starting at their margins. Between the outer, later ± browned sheaths are several, 3–4 (5) mm long, vitreous- to yellowish-white larvae or flattened flax seed-like, brown puparia. A. fatua, sativa: Mayetiola avenae

12a Single or several shoots of already developed plants stunted, predominantly at terminal parts; enveloped primordia of plant parts accumulated to ± spindle- or almost cigar-shaped galls. Larvae up to 7 (9) mm long, glossy white-yellow, with mandibles [buccal hooks], with 2 small caudal conical spiracles. Feeding on the central shoot or on upper internode. Pupa yellow-brown, ± flattened. A. sativa: Chlorops pumilionis

12b Plants very leafy, severely stunted, hardly developing shoots; infected shoots ± distinctly swollen at base, onion-like. Leaves short, thickened, undulately curved; becoming yellow and brown prematurely. Containing many eelworms in ± spongy parts. A. fatua, sativa: Ditylenchus dipsaci

13a Ovaries temporarily slightly swollen, soon occupied by a black mass of spores => 16

13b Malformation of large parts or of inflorescence, caused by animal parasites => 14

14a Malformations caused by gall mites => 15

14b Axis of the inflorescence distinctly narrow-undulately curved; panicle clustered; malformations caused by aphids. A. fatua, sativa incl. orientalis, strigosa: Sitobion avenae

14c Flowers swollen, contain yellow midge larvae. Avenula pubescens: Contarinia avenae

15a Spikelets incompletely developed. Panicle often remains largely hidden in leaf sheaths of the generally stunted plant; stalk of inflorescence shortened, ± undulate to screw-like compressed sheaths and the slightly swollen, protruding glumes often carmine- to blue-red. Terminal part of stem or panicle inside the sheath often twisted like corkscrew, covered with many mites which look like crumbly meal. A. sativa: Steneotarsonemus spirifex

15b Spikelets elongated, stalk often surmounting the flower and developing new spikelets. A. sativa: Cause unknown – ? gall mite

16a Diseased shoots develop accelerated longitudinal growth and surmount the healthy ones for a short period; infected spikelets broader and shorter, soon completely destroyed by a black-brown mass of spores, which during eruption turns the unfolding panicle to dust with only the midrib remaining. A. barbata, fatua, nuda, sativa, sterilis incl. subsp. ludoviciana, strigosa: Ustilago avenae

16b From stripes of smut on leaves of A. barbata, sativa incl. ssp. orientalis, Avenula pubescens is furthermore recorded the exceedingly rare Ustilago striiformis

16c Similar infestation, the spore mass, however, develops between two intact valves as a closed, rather compact, non-dusty smut grain. A. barbata, fatua, nuda, sativa, sterilis incl. subsp. ludoviciana, strigosa: Ustilago avenae

1a Galls on leaves, inflorescences or flowers => 7

1b Galls on axial parts such as twigs, branches and stems => 2

2a Galls on young shoots => 4

2b Malformations on stems or branches => 3

3a Rimmed wounds caused by cancers on branches, rarely on younger stems. “Nectria-cancer”. T. cordata, platyphyllos: cf. Neonectria ditissima

3b Older axial parts often with well-developed, oblong-spindle-shaped or compact oval swellings: Viscum album

4a Gall causers live outside the malformations => 6

4b Gall causers develop inside the galls => 5

5a Up to 8 mm wide swellings on all sides or one-sided, ± globular on the one-year old twigs. Inside is an expanded tunnel containing a caterpillar with distinct head capsule. Tilia spp.: Unidentified lepidopteran

5b Galls on young shoots ± globular to acuminated, barrel-shaped, succulent, up to 10 (20) mm across; at various locations, usually on suckers, especially the buds, which are often ± extensively involved in the gall formation. Each chamber containing a single sulphur- to lemon-yellow larva. Tilia spp.: Contarinia tiliarum

5c Plurilocular swellings on young shoots. T. cordata, platyphyllos: Contarinia ramicola

6a Axial parts of the younger shoots with slightly rimmed depressions containing a pear-shaped, 2.5–3 mm scale: Chionaspis salicis

6b Furthermore, with similar biology: Diaspidiotus gigas

6c Depressed gall-like grooves, occurring predominantly in branch axils. Tilia spp.: Xylococcus filiferus

6d Spring shoots terminally twisted. Leaves clustered nest-like, leaf blades rolled, curved and curled round each other. T. cordata, platyphyllos: Patchiella reaumuri

7a On inflorescences or flowers => 23

7b On leaves => 8

8a On developing, already unfolding or mature leaves => 9

8b The more or less developed young leaf blades terminally on stunted shoots remain irregularly crumpled and upwardly folded. Venation undulately disfigured, slightly thickened, sometimes more pubescent. The folds contain several at first white, then orange-yellow to reddish larvae. Tilia spp.: Dasineura thomasiana

9a Leaf blades browned, curled or with rolled margins and sometimes with abnormally felt-like pubescence, on the petioles and even extending onto the shoot => 16

9b Leaves with different, more or less constant localised galls => 10

10a Galls semiglobular, nodular or horn-like, always often with only narrow opening, towards the underside of the leaf => 13

10b Galls closed, ± globular to egg-shaped or flat pustule-shaped => 11

11a Galls irregular rotund to acuminate rotund-oval => 12

11b Leaf blade usually with several to sometimes many flat, circle-shaped parenchyma galls, hardly protruding on the upper side, on the underside slightly arched, pustule-shaped, sometimes reddish or yellowish brown rimmed. Containing a single white larva. Tilia spp.: Physemocecis hartigi

12a Galls dispersed on the leaf blade, often many per leaf; tough-walled, rotund, up to 8 mm wide and about 4 mm high; on one side arched-conical, on the other side rather bulging disc-shaped; predominantly protruding more on the upperside; often yellowish or reddish rimmed later on. From the conical part separates centrally at maturity an often differently coloured, brownish, cylindrical-conical, longitudinally grooved inner gall, containing a glossy white to pale yellow larva. Tilia spp.: Didymomyia tiliacea

12b Galls on petioles or veins; acuminated, rotund-oval, about 4–6 mm long, succulent, pale green; one-, more rarely more-chambers; each chamber containing a single sulphur- to lemon-yellow larva. Tilia spp.: Contarinia tiliarum

13a Galls nodule-shaped or wart-like => 14

13b Leaf blade on upperside with slender, about 5 up to even 10 (15) mm long horn-like, so called “nail galls”. Galls scattered on leaf blade, at first green, eventually yellowish, reddened or browned, glabrous or ± pubescent, acuminate, partially also rounded. Underside with narrow, pubescent opening; inner wall with loose, cylindrical pointed hairs of various length. Similar galls with rather host-specific mites:

a On T. cordata, platyphyllos, tomentosa: Eriophyes tiliae

b On T. argentea: Aculus argenteae

14a Galls at any place on the leaf blade => 15/p>

14b Leaf blade often with many almost semiglobular upward protrusions in the vein axils. Galls at first often strongly pubescent, eventually ± glabrous. Cavity open on underside and clothed often with prominent tufts of 1-celled, cylindrical, acuminate hairs. Tilia spp.: Eriophyes exilis

= In the vein axils of many woody plants occur hair formations, tuft-like, or arranged in rows, which may sometimes be even slightly bulged on the upperside of especially young leaves of lime trees. These “acarodomatia” or “mite pubs” may secondarily be inhabited by free-living mites, but are not true galls

15a Scattered nodular pouch galls; occurring on both sides of leaf; often many per leaf blade. Up to 3 mm long, up to 1.5 mm wide. Outside at first finely haired, eventually becoming glabrous, often with only some rigid hairs at base. Opening slit-like, densely pubescent. Cavity with tufts of simple hairs. T. platyphyllos: Phytoptus bursarius

15b Similar, flatter wart-shaped pouch galls, densely haired inside. T. cordata, platyphyllos: Phytoptus stenoporus

16a Leaves and additionally sometimes also the petioles with abnormal pubescence => 20

16b Leaf blades arched and curled or rolled at their margins => 17

16c Leaf blade browned. True gall? T. platyphyllos, cordata: Aculus ballei

17a Rolls of leaf margin => 18

17b Leaf blade variously ± irregular spoon- or trowel-like downwardly deflected, curled and locally coloured dark green. Tilia spp.: Philaenus spumarius

18a Roll in cross section larger than 2 mm; of varied length => 19

18b Roll narrow, compact, undulately-nodular thickening; ± pale green, usually rolled downward, occasionally upward. They often occur either with several per leaf blade and only a few mm long, or are sometimes coalescing and widely expanded. The inside is clothed with simple, pointed hairs. Tilia spp.: Phytoptus tetratrichus

19a Margin rolled upwards. Roll compact, succulent-cartilaginous thickening, brittle, wall almost glabrous, ± pubescent, yellow-green or often crimson- to violet red. Inside glabrous; often with several yellow-red larvae. Tilia spp.: Dasineura tiliae

19b Margin often on both sides of leaf with widely expanded, loose, not thickened, usually distantly-undulate upward roll. The leaf parenchyma is blotch-like mined inside the rolls up to both epidermises. Containing a single larva. Tilia spp.: Parna tenella

20a Erinea at various locations on the leaf blade => 22

20b Abnormal hair formations in the vein axils or along the venation => 21

21a Erinea flaky, white, sometimes slightly reddened, extending along the veins. On the upperside often coalescing at the branching of the veins; on the underside usually developed more sparsely. Tilia spp.: Eriophyes exilis and/or: Eriophyes nervalis

21b On the upper side in the vein axils almost semiglobular arched, haired protrusions, which eventually become glabrous. The cavities on the underside are often clothed with projecting dense tufts of 1-celled acuminate cylindrical, soon browned hairs. Tilia spp.: Eriophyes exilis

22a Densely pubescent erinea, situated between the veins, at first whitish to reddish to violet, finally brownish. Making oblong-oval patches on the upperside and/or underside, which may coalesce in various ways. Hairs cylindrical, at top often club-shaped, also bent or slightly twisted. T. cordata, platyphyllos: Eriophyes exilis

22b Similar erinea on the underside consisting of cylindrical hairs, rarely on upperside. Occur in distinctly margined, up to 5 mm, rotund- to oblong-oval patches which are clearly arched on the opposite side. T. tomentosa: Phytoptus erinotes

23a Bracts with horn-like, or felt-like galls or with rolled margins => 24

23b Globular or ± acuminated, oval, 5–8 mm, succulent swellings of flower buds, on midrib of the bracts or on the stalks of the inflorescence. Tilia spp.: Contarinia tiliarum

24a Leaf blades with erinea or horn-like- to nodular galls => 26

24b Leaf rolls => 25

25a Roll arched upward, succulent, brittle; often extending onto midrib; with uniform surface, glabrous or haired, often conspicuously reddened. Larvae yellow-red. Tilia spp.: Dasineura tiliae

25b Margin with narrow, leathery, undulate-nodular galls caused by mites These are pale green, up to 1 mm high, about 2–10 mm long, may coalesce into larger stripes, glabrous or haired rolls. Tilia spp.: Phytoptus tetratrichus

26a Leaf blades with erinea of various expansions. Erinea sometimes extending onto galls of other origin. Tilia spp.: Eriophyes exilis and/or: Eriophyes nervalis

26b Leaf blade with horn-like galls. Tilia spp.: Eriophyes tiliae

1a On parts above ground => 2

1b Roots with nodular or spindle-shaped swellings, up to 4 mm long. S. media: Meloidogyne hapla

= Cyst eelworms on roots belong to Heterodera schachtii, H. galeopsidis or H. trifolii.

2a On inflorescences, flowers or fruits => 19

2b On stems, buds or leaves => 3

3a Malformations on shoot tips, or extending over large areas of plant => 5

3b Galls defined locally, solitary or with several to many on leaves and stems => 4

4a Galls multi-cellular, flat hemispherical, wart-shaped; nutritive cell depressed at top up to 1 mm across; at first yellow-red. In large numbers on leaves, stems, flower peduncles and even calyx; solitary or coalescing into later on brownish, ± expanded, inconspicuous ridges or crusts. S. media, nemorum:
Synchytrium stellariae

4b Leaf blades with rotund, veins, stalks and stems with oblong-oval or spindle-shaped, up to 6 mm long, ± yellow margined, sometimes conspicuously arched bulges, soon covered with ring-shaped arrangement or ± coalescing groups of dark-brown, 2-celled teliospores. Stellaria spp.: Puccinia arenariae

5a Galls confined to shoot tips or lateral buds => 15

5b Malformations more extensive => 6

6a Stem is only secondarily involved in gall development => 7

6b Stem severely stunted, conspicuously spongy and thickened, especially at base, – distorted, pale green. Lateral organs clustered, ± stunted, partially similarly swollen and accordingly bent. Occasionally localised galls on well-developed stems, usually strongly curved. Leaf blades occasionally basally ± distorted. S. media: Ditylenchus dipsaci

7a Malformations caused by animals => 10

7b Malformations caused by fungi fructifying at surface => 8

8a More strongly infected shoots elongated, slightly hypertrophied, inserted leaves pale, slightly thickened; often bent, spoon-like, or irregularly curved; later on with down of branched conidiophores. Galls facultative => 9

8b Shoots etiolated; internodes lanky, elongated; leaves pale, leaf blades reduced, with expanded, scattered, golden-yellow sori on underside. Stellaria spp.: Melampsorella caryophyllacearum

9a On S. alsine, calycantha, graminea, holostea: Peronospora parva

b9 On. S. media, neglecta, nemorum, pallida: Peronospora alsinearum

10a Many terminal leaves disfigured on otherwise normal shoots => 11

10b At infestation site one or several internodes are slightly shortened on one side and ± curved. Leaves accordingly clustered; leaf blades usually arched, spoon-like, curled and locally deep green. Stellaria spp.: Philaenus spumarius

11a Malformations caused by aphids => 13

11b Malformations caused by mites or thrips => 12

12a Leaf blades ± curved; narrowly rolled upwards at margin. Usually on many terminally, clustered, sometimes ± discoloured leaves. S. alsine, graminea, holostea, palustris: Cecidophyopsis atrichus

12b Leaf blades of many terminal leaves± disfigured, rolled upwards and twisted; tissue inside stunted and undifferentiated. Whole plant, and inflorescences if present, atrophied. S. alsine, graminea, holostea, media: Taeniothrips atratus

13a Leaves variously loosely rolled downwards => 14

13b Leaves conspicuously pod-like, folded upwards over the midrib, sometimes ± discoloured and curved, sickle-shaped. Leaves accumulated close to the ± stunted shoot tip. S. graminea, holostea: Brachycolus stellariae

14a Shoot stunted at tip; leaves rolled inwards. Aphid 2–2.5 mm long, red-brown. S. media, nemorum: Myzus certus

14b Roll of leaf margin on S. media, nemorum caused by green aphids, 2–3 mm long: Aulacorthum solani

15a Galls longer than 5 mm, mainly on tips of main- and side shoots => 16

15b Side-, sometimes also terminal buds of S. alsine, graminea transformed into an elongate-oval or acuminate egg-shaped capsule-like gall, about 2–3 (4) mm broad and 3–5 mm long, consisting of two stunted, thickened leaf primordia: Ametrodiplosis duclosii

16a On S. holostea => 18

16b On other Stellaria species => 17

17a The severely stunted terminal outer pair of leaves on shoot are sessile, directed upwards and converging, mussel-like. Swollen at base, thickened and discoloured. Browning and rapidly decaying after departure of larvae. Containing several at first white, then lemon-yellow larvae. S. holostea, media: Macrolabis stellariae

17b Similar galls on S. nemorum. Larvae white to cream-coloured: Macrolabis buhri

18a Terminal ± severely stunted leaves on shoot transformed into an erect, ± pale green, soft, acuminate conical, basally slightly thickened, rapidly necrotic gall. Containing white-yellow larvae: Macrolabis holosteae

18b Terminal leaves on shoot severely stunted, transformed into conspicuously dark-brown, tough-walled, acuminate egg- to spindle-shaped, galls. Containing white larvae: Dasineura stellariae

18c Axillary leaf bud galls contain white larvae: Dasineura silvicola

19a Malformations of several parts of developing flowers or anthers => 20

19b Ovaries are not developed in disfigured capsules which remain small. Containing a single white larva. S. holostea: Dasineura holosteae

20a Flower buds of different age bloated on usually stunted stalks; ± unopened => 21

20b Corolla- and calyx leaves atrophied on usually bloated, infected flowers, often in large numbers per plant, spreading later on, with dusting of spores. S. alsine, calycantha, graminea, holostea, longifolia, media, palustris: Microbotryum stellariae

21a Spores inside early stunted buds, interiorly soon largely destroyed, ± globular to blunt conical. Spores united in balls discoloured ± red-brown in various gradations. Belonging to the smut fungus Thecaphora saponariae species complex => 22

21b Fungus with spores on branched conidiophores, developing on outside of calyx of globularly bloated, sometimes normally fruiting flowers => 9

22a On S. graminea: Thecaphora saponariae

22b On S. holostea, media: Thecaphora alsinearum

1a Malformations on inflorescences or flower => 23

1b Malformations on leaves or stem parts => 2

2a Galls on single or several terminal leaves => 5

2b Malformations exclusively or mainly on stems => 3

3a Pock-shaped galls on stems caused by scale insects or cancer-like proliferations on older organs => 4

3b Branches with spindle- to club-shaped swellings bearing: Viscum album

4a Woody stems with ± expanded cancer-like proliferations. Sorbus spp.: Eriosoma lanigerum

4b Closed, ± rotund galls, mainly on root collar. Sorbus spp.: Agrobacterium tumefaciens

4c Young shoots sometimes ± stunted or crippled often with many, centrally depressed rotund-oval pocks; containing scale below. Sorbus spp.: Chionaspis salicis

4d Dirty-grey rotund scale insects, about 1.2–1.6 mm long, live in irregular, usually rimmed depressions on bark of young stems of e.g., S. aucuparia: Epidiaspis leperii

5a Expanded curls or similar malformations on several mainly terminal leaves => 15

5b Leaf folds or -rolls, hair felts or local, sometimes clustered malformations on younger or older leaves => 6

6a Swellings caused by fungi, to varied extents on underside, yellow, also red, often yellow margined with conspicuous cylindrical to cornicular aecia protruding from the galls => 12

6b Malformations caused by animals => 7

7a Leaf blades folded, rolled or with pock-like swellings => 9

7b Leaf blades with abnormal pubescence => 8

8a Abnormal pubescence on leaf underside, mainly following venation. S. aucuparia, domestica, intermedia, etc.: Eriophyes sorbi

8b Expanded, at first whitish, then reddish to brownish erinea on under- or also on upper side of leaves, without close association with venation. Infected leaf blades are, if strongly infected, occasionally additionally disfigured during their development. Hairs compact, blunt-cylindrical or globular. S. aria, aucuparia, torminalis, etc.: Phyllocoptes sorbeus

9a Leaf blades with ± distinct rolls of margin => 11

9b Leaf blades folded along midrib or with pock-like swellings => 10

10a Leaflets on S. aucuparia completely or partially folded upwards along the ± curved, hardly thickened midrib, forming almost pod-like galls ± discoloured at base. Similar malformations on S. torminalis in only partially galled leaf blades. Containing several white larvae: Contarinia sorbi

10b Leaf blades with many pocks with narrow exit hole on undersides, weakly protruding on both sides, often less than 2 mm across, sometimes variously coalescing, at first pale-green, then browned. Sorbus spp.: Eriophyes sorbi

= a further subdivision according to host:

a On S. aucuparia: Eriophyes sorbi

b On S. aria: Eriophyes arianus

c On S. torminalis: Eriophyes torminalis

11a Leaf blades of almost unfolded leaves rolled upwards. Roll slightly thickened, ± discoloured. S. aucuparia: Unidentified gall midge

11b Leaf blade bent upwards, curved and crumpled. Larvae reddish-yellow. S. aria: Dasineura sp.

12a Wall of aecia at maturity thread-like rupturing up to base => 13

12b Peridium long horn-shaped; about 3‒4 mm long, up to 0.5 mm broad; its margin not, or only slightly, rupturing at maturity. Single cells broad, about 31–35 µm across. Inner- and side walls provided with fine or short, obliquely running ridge-like tubercles. Swellings usually weak cushion-like swollen. Sorbus spp.: Gymnosporangium cornutum

13a Galls like those of previous fungus; usually only flat cushion-shaped. Peridium cylindrical, only up to 0.5 mm broad; cells distinctly narrower than those of previous and next fungus; the wall thickenings consist at least of only smaller ridges => 14

13b Swellings usually strongly bumpy arched. Peridium cylindrical, 0.5–1 mm broad and protruding up to 3 mm; cells about 31–35 µm large, tough-walled, minute-warty. Sorbus spp.: Gymnosporangium tremelloides

14a Pseudoperidia remarkably slender, only up to about 0.25 mm broad, up to 2 mm high. Cells 18–25 µm broad; side walls with robust, transversely and obliquely running oblong tubercles and short ridges. Aeciospores 21–29 x 17–21 µm. Usually distinctly developed galls. S. torminalis, latifolia: Gymnosporangium confusum

14b Pseudoperidia up to about 0.5 mm wide and 2–3 mm long. Cells 14–20 µm wide; the strongly thickened side walls with many tubercles of unequal size and irregular shape. Aeciospores 26–32 x 22–25 µm large. Fungus on S. aucuparia, latifolia, torminalis on usually hardly swollen patches, often only developing spermogonia. Gymnosporangium clavariiforme

15a Malformations caused by spittlebugs or psyllids => 22

15b Malformations caused by aphids or fungi => 16

16a Malformations by aphids => 17

16b Leaf blade with conspicuous, bladder-shaped swellings of fungus, at maturity appearing frosted by filamentous erinea which consist of asci. S. chamaemespilus: Taphrina aff. deformans

16c s causer of small disfiguring spots or more expanded curlings on leaves. S. torminalis: Taphrina sorbi

17a Leaves ± disfigured, accumulated nest-like at shoot tips, only slightly discoloured => 18

17b Similar accumulations of usually soon conspicuously yellow or red discoloured, bladder-like swollen leaves, bent over at their tips. S. torminalis: Dysaphis aucupariae

18a Aphids yellowish-green or green => 19

18b In leaf-roll galls on S. aria. Aphids yellowish-white, furthermore close to Dysaphis plantaginea: Dysaphis ariae

19a Leaves not conspicuously curved, ± strongly curled => 20

19b Leaves on stunted shoots, strongly rolled, usually over the tip, accumulated into loose clusters, dropping in autumn; not discoloured and curled. Aphid foliage-green, with rather long, black, siphunculi Sorbus spp.: Aphis pomi

20a Aphid green to olive-brownish or darker and in that case with thick wax covering; distinguished by marginal tubercles on all body segments and the very short triangular cauda => 21

20b Aphid 1.5–2.5 mm long, green. Cauda tongue-shaped, siphunculi pale with dark tip; antennae slightly shorter than half the body length. S. aria, aucuparia, torminalis: Rhopalosiphum oxyacanthae

21a On S. aucuparia, hybrida. Leaves rolled downwards over their tips, disfigured and curled. The dense nest-like, globose accumulations dry out and often remain on the tree until the following spring. Dysaphis sorbi

21b On S. torminalis, rarely on S. aucuparia. Usually the terminal leaves show a yellowish to reddish discolouration of the venation. Dysaphis aucupariae

22a Leaves developing in spring stunted, variously disfigured, usually with several flat yellowish larvae on underside. S. aucuparia, aria and relatives : Cacopsylla sorbi

22b Usually several flatted froth-covered nymphs on the underside of the leaves, each in a shallow depression. S. aria, aucuparia, domestica, torminalis: Cacopsylla albipes

22c Similar malformation. S. aria: Cacopsylla breviantennata

23a Parasite inside disfigured flowers => 25

23b Inflorescence ± stunted, compact; flowers stunted and disfigured => 24

24a Organs of young inflorescences sometimes with the neighbouring disfigured leaves ± densely bunched together. S. aucuparia: Dysaphis sorbi

24b All parts of young inflorescence stunted. Buds clustered into irregular pseudo-umbels or into squarrose panicles. All green parts densely pubescent. S. aucuparia: Phyllocoptes sorbeus

25a Flower buds swollen, unopened, yellowish-green. Corolla at first not discoloured. Inside are several pale yellow, jumping larvae. S. aria, aucuparia: Contarinia floriperda

25b Flower buds slightly enlarged; corolla unopened, soon browned. With a beetle larva inside. S. aucuparia: Anthonomus conspersus

= Also Anthonomus pomorum may occasionally occur on S. aucuparia

1a Malformations on higher situated parts above ground => 9

1b Variously shaped malformations on roots, stolons, tubers, root collar => 2

1c White, velvet cover on all parts of the plant, even underground. Attacked parts turn brown and wither. The conidia (in fact, sporangia) are ovoid or lemon-shaped, with an indistinct apical papilla. They are formed at the tip of seemingly undifferentiated hyphae, that here and there show irregular swellings. S. dulcamara, melongana, nigrum, physalifolium, tuberosum; also on Lycopersicon: Phytophthora infestans

2a Malformations only or mainly on roots => 7

2b Malformations on runners, tubers or on root collar, on other organs only under particular conditions and usually occurring simultaneously with previously reported malformations => 3

3a Malformations on stolons or tubers => 5

3b Malformations on root collar or on basally situated buds => 4

4a Gall formation not exclusively dependent on buds. Proliferations ± compact; rugose from outside, soon enclosed in tougher, corky tissue. Cavities inside many, running up to periphery. Inducer hardly microscopically detectable. Never on tubers and only exceptionally on stolons. “Bacterial-cancer|”. S. tuberosum: Agrobacterium tumefaciens

4b Proliferations usually close to ground; only developing from buds; soft at surface. Spores distinctly detectable in tissue. Galls very variable, depending on kind of host and developmental stage, time and degree of infestation; ± fissured, often coral-like; with strongly reduced primordia of organs. Pale below ground, above ground buds greened. Mainly on tubers, exceptionally on stolons or leaf parts; in potatoes never occurring on roots. “Potato-cancer”. S. tuberosum: Synchytrium endobioticum

5a Swellings usually less than 10 mm, flat; usually no connection with buds; on stolons or also on tubers => 6

5b Galls expanded, only developing from buds of tubers; at surface coral- or cauliflower-like, incised; at first white and compact, later on dark brown and rotting. On single or many buds, sometimes enveloping the complete tuber. “Potato-cancer”. On S. tuberosum and many tuber bearing relatives: Synchytrium endobioticum

6a The galls, about 3–6 mm long, rotund to oval, wart-like, mainly developing on tubers and on stolons, occasionally occurring mainly also on roots, at first white, later on dark-brown are ± rotund-oval, bladder-shaped and contain in the strongly hypertrophied nutritive cells of the swollen parenchyma masses of ball-like accumulated, rotund spores, made conspicuous by their dark colour. “Powder scab”. S. tuberosum as well as many, especially tuber bearing relatives: Spongospora subterranea

6b Developing tubers, almost only close to lenticels, with partially strongly arched swellings, also encroaching into the tissue, consisting of living cells, which contain many eelworms in between; weaker, mainly one-sided swellings sometimes simultaneously on stolons. S. tuberosum: Ditylenchus dipsaci

= Damage of tubers, known as “worm rot” has been caused by Ditylenchus destructor

7a Gall development inconspicuous from the outside, of irregular shape => 8

7b Roots with swellings usually on all sides, 2–5 mm long, slender spindle-shaped or ± conspicuous nodular, smooth-walled, sometimes joining, containing eelworms. S. dulcamara, melongena, nigrum, tuberosum, villosum: Meloidogyne spp.

7c Conspicuous, usually one-sided, sometimes fissured, almost cancer-like proliferations on thicker roots are caused by “Powder scab”: Spongospora subterranea

8a Roots externally not galled, or only on particular substrates, with slightly spindle-shaped galls. The temporarily about poppy-seed size, at first white, later on yellow, eventually brown, soon dropping cysts with giant cells developed inside roots. The healthy parts above the infestation site usually develop many “starvation roots”. On S. tuberosum and many wild potatoes, occasionally on S. dulcamara, luteum, melongena, also several forms of S. nigrum, etc.: Globodera rostochiensis

8b Roots with smaller, at first pale, later on brown galls, about 1–2.5 (4) mm long, wart-like, at surface often ± fissured, sometimes densely arranged or coalescing; similar infestation sometimes also on subterranean stem internodes. S. dulcamara, villosum, nigrum as well as several varieties and forms: Synchytrium endobioticum

9a Galls on stems, shoot tips or leaves => 11

9b Malformations on inflorescences or flowers => 10

10a Inflorescence largely stunted; flower primordia clustered into often long, ± raceme-like arranged galls. Flowers leafy in variously shaped, often densely haired rosettes. S. dulcamara: Aceria lycopersici

10b Flower buds strongly swollen, unopened. Galls greenish or ± violet tinged. Stamens and ovaries thickened and ± curved. Containing several ivory-white larvae. S. dulcamara: Contarinia solani

= Orange-yellow midge larvae of Macrolabis dulcamarae live as inquilines in galls on S. dulcamara

10c Berry disfigured and ± bumpy. Containing a single or several larvae. S. nigrum, tuberosum: Asphondylia trabuti

11a Malformations mainly on leaves or on shoot tips => 12

11b Gall development mainly on stems, occasionally over two or more internodes ± strongly shortened, curved, spongy, swollen and discoloured pale green. Leaves clustered at infestation site; development stunted; usually stalks, and midrib similarly galled; leaflets stunted and ± disfigured. Diseased parts usually prematurely withered. S. robustum, villosum, memphiticum, nigrum, tuberosum: Ditylenchus dipsaci

12a Expanded malformation of several organs on tips or terminally on shoots => 13

12b Leaf blade underside usually with many ± golden-yellow wart-like galls, less than 1 mm long. Also on petioles and basal stem parts; sometimes joined into ridges or crusts. S. dulcamara: Synchytrium aureum

13a Malformations caused by aphids => 15

13b Malformations caused by spittlebugs or mites => 14

14a All organs in often expanded arrangement terminally on apical or lateral shoots, and -buds ± stunted, bearing strongly reduced, often densely clustered, whitish or grey pubescent leaflets. Malformations sometimes up to 60 mm long and 40 mm wide; also encroaching into inflorescence. Lycopersicum esculentum; Solanum dulcamara, nigrum: Aceria lycopersici

14b Internodes close to shoot tip locally stunted and curved. Inserted leaves clustered, axial parts and margins curved; locally deep green. Similar malformations on larger leaves without involvement of axial parts. Lycopersicon esculentum, Solanum spp.: Philaenus spumarius

15a Aphids yellow or green => 17

= Many aphids, especially the host alternating species, inhabit not only potatoes, but also other hosts, during summer, preferably on leaves of varying age, which become variously disfigured. Aphids of some species may, in the later vegetative period, develop more luxuriously on plants already diseased by virus. It may be difficult to determine whether malformations are primarily the result of virus, making aphids secondary inhabitants, or primarily caused by aphids

15b Aphids almost black => 16

16a Leaves of ± stunted shoot tips clustered; ± deflected and curled over their top. Aphid only separable from the next species by microscopic characters, but preferentially colonising S. nigrum: Aphis fabae solanella

16b Similar malformations. S. nigrum, tuberosum: Aphis fabae fabae

17a Antennae longer than body => 18

17b Antennae of apterae not exceeding tip of abdomen, distinctly shorter than body => 19

18a Apterae pale yellowish to green, with a darker green spot at insertion of each siphunculus. Body pear-shaped, broadest at abdomen. 1.8–2.9 mm. Siphunculi pale, with darker tip, 1/5–1/4 body length, about twice as long as cauda. Alates green, with yellowish-brown to black-brown thorax, and with dark transverse stripes on abdomen. Lycopersicon esculentum, Solanum dulcamara, nigrum, tuberosum, villosum: Aulacorthum solani

18b Aphid green, often with a dark, green longitudinal stripe on back. Body spindle-shaped oval, glossy in adults, frosted in froth-covered nymphs. 2.5–3.6 mm. Siphunculi brownish, ¼–⅓ of body length, twice as long as cauda. Alates with pale brownish-yellow thorax, otherwise lacking pigmentation on back. Lycopersicon esculentum, Solanum dulcamara, melongena, nigrum, tuberosum: Macrosiphum euphorbiae

19a No tubercles on head. Siphunculi cylindrical or slightly conical. Abdomen of alates without dark median patch => 20

19b Head with tubercles at antennal bases. Apterae pale green, rarely reddish. Siphunculi pale, slightly club-shaped. Alates with head, thorax, a large median patch on abdomen, dark brown-black. Lycopersicon esculentum, Solanum dulcamara, melongena, pseudocapsicum, tuberosum: Myzus persicae

20a Apterae yellow to greenish-yellow. Siphunculi yellowish-green with brownish tips. S. dulcamara, melongena, tuberosum: Aphis nasturtii

20b Apterae dark-green spotted to dirty yellow. Siphunculi black, slightly conical. Lycopersicon esculentum; Solanum laxum, melongena, tuberosum: Species complex of Aphis gossypii

1a On parts above ground => 5

1b On roots or root collar => 2

2a Galls on roots => 3

2b Whitish, rotund, one-chambered swellings on root collar, up to about 6 mm long, sometimes with several and ± coalescing. Each chamber containing a single white larva. S. alba, arvensis: Ceutorhynchus assimilis

3a Malformations mainly on lateral roots, only exceptionally more than 5 mm long and 3 mm wide => 4

3b Galls of very variable size, conspicuous on main- lateral roots; spindle-shaped to cylindrical, usually more than 10 mm, up to even 20 mm long and about 4–8 mm wide; sometimes encroaching from the main root onto the branchings, also coalesced into larger groups; succulent. Inside are masses of minute spores. “Clubroot”. S. alba, arvensis & subsp. allionii: Plasmodiophora brassicae

4a Roots with small nodular to elongate cylindrical, usually many swellings bearing several lateral roots. S. alba, arvensis: Meloidogyne hapla

4b Outside of roots unchanged; inside with giant cells, bearing poppy seed-sized white to brown cysts. S. alba, arvensis: Heterodera sp.

= Scattered reports of damage by H. schachtii, H. trifolii and H. cruciferae

5a Malformations on inflorescences, flowers or siliques => 16

5b Galls on leaves, axial buds or stems, in the latter case sometimes encroaching onto inflorescences => 6

6a Gall formations ± delimited in expansion, usually only on parts of infected organs => 10

6b Malformations of irregular shape and expansion; usually on various organs => 7

7a On organs of ± fully developed plants => 8

7b Young plants severely stunted and disfigured. Petioles and main venation as well as shoots stunted, pale green, spongy. S. alba, arvensis: Ditylenchus dipsaci

8a The inducers develop on the outside of mostly terminal malformations => 9

8b Stem slightly swollen to large extent. In the increased pith of the ± disfigured, stunted and sometimes distorted plants live several beetle larvae. S. arvensis: Ceutorhynchus napi

9a Axis of the tips of vegetative- or developing flowering shoots ± stunted; the inserted organs clustered, development stunted. Leaf blades curved, curled. Flower buds or flowers variously disfigured. S. alba, arvensis: Brevicoryne brassicae

9b Stem locally stunted, sometimes bent; the inserted leaves clustered; the leaf blade arched, at the infestation site ± curled and discoloured deep green. S. alba, arvensis: Philaenus spumarius

10a Galls on well-developed stems or leaves => 11

10b Terminal, also lateral shoots, and axillary buds severely stunted in longitudinal growth. Leaves clustered, the inner ones developing into rosette- to bud-like galls, especially thickened at base. Containing several whitish to pale yellow, jumping larvae. S. alba, arvensis: Contarinia nasturtii

11a Malformations caused by fungi => 15

11b Malformations caused by animals => 12

12a Causers inside entirely deep green galls => 14

12b Causers develop outside the malformations => 13

13a Leaf blade with small, localised swellings. S. arvensis: Inducer unidentified – ? psyllid

13b Leaf blade ± folded, or variously deflected or bent upwards at margin, usually pale green, sometimes reddish marbled. S. alba, arvensis: Brevicoryne brassicae

= Lipaphis erysimi, which is facultatively cecidogenic on several crucifers, also occurs on Sinapis.

14a Galls flat spindle-shaped, 10–15 mm long; mainly on midrib, midrib or petioles, occasionally on stems. Containing a single larva. S. alba, arvensis: Ceutorhynchus chalybaeus

14b Galls flat rotund-oval, including the finer venation situated in the leaf blade. S. arvensis: Ceutorhynchus leprieuri

15a Leaf blade on underside with rotund bulges, up to 10 mm wide, or young stem parts ± spindle-shaped, often expanded, which are at first glossy, porcelain-like, later rupturing and with mealy dusted sori. S. arvensis, rarely S. alba: Albugo candida s. lat.

15b Leaf blade with weak bladder-like swellings; young stem sometimes with conspicuous, usually one-sided, ± distorted bulge-like swellings, soon covered with a whitish down of branched conidiophores. S. alba & subsp. dissecta, arvensis & subsp. allionii: Hyaloperonospora brassicae

16a Malformations on inflorescences or flowers => 17

16b Siliques usually only insignificantly stunted and disfigured; ± sterile, early (prematurely) maturing; contain several white larvae. S. alba, arvensis: Dasineura napi

17a Malformations caused by fungi => 22

17b Malformations caused by other inducers => 18

18a Galls on single or several flowers of inflorescences that are not additionally conspicuously stunted => 21

18b Axis usually ± stunted with clustered flower buds => 19

19a Malformations not abnormally pubescent => 20

19b Calyx little changed; inner flower parts transformed into ± leaf-like organs or greened; infected parts excessively pubescent. S. arvensis: Unidentified gall mite

20a Flower buds clustered on the stunted, hardly swollen axial parts. Containing several white to pale yellow jumping larvae. S. alba, arvensis: Contarinia nasturtii

20b Flowers largely stunted; at terminal parts of racemes sometimes normally arranged or more clustered; only the sterile remaining ovary is greatly enlarged. S. arvensis: Inducer unidentified – ? aphid

21a Flower buds enlarged, inflated, unopened. Corolla ± stunted. Stamens shortened and thickened. Containing several white, non-jumping larvae. S. alba, arvensis: Gephyraulus raphanistri

21b Galls similar. Larvae whitish to lemon-yellow, jumping. S. alba, arvensis: Contarinia nasturtii

22a Diseased flowers, with exception of stamens, often conspicuously enlarged. At first glossy, porcelain-like, soon bearing mealy dusted sori. Mainly occurring on single flowers; sometimes flower peduncle and midrib of galled inflorescence is also often elongated. S. alba, arvensis & subsp. allionii: Albugo candida

22b In the infected flowers, often inserted on short stalks, only the ovaries are hypertrophied, later on bearing down of branched conidiophores. All other organs ± strongly atrophied. Usually several to many flowers on the ± swollen and distorted axis of inflorescences are similarly galled, also covered with conidiophores. Galls partially contain oospores. S. alba & subsp. dissecta, arvensis & subsp. allionii: Hyaloperonospora brassicae

1a Malformations on parts above ground => 2

1b Lateral roots usually with several nodule- to spindle-shaped swellings from which originate some lateral roots. P. anisum: Meloidogyne hapla

2a On flowering or fruiting inflorescences => 17

2b On vegetative parts => 3

3a Gall formations primarily affect leaf sheaths of leaf blades of leaflets => 8

3b Galls primarily on petioles, midrib, leaf veins or on stems => 4

4 Fungi live inside galls; but fruiting bodies develop at gall surface => 5

4b The scale-covered nymphs develop in rimmed depressions on spindle- to barrel-shaped or bulging swellings of leaf sheaths or basal stem parts. P. saxifraga: Planchonia arabidis

4c Spindle-shaped one-chambered swelling of stem or rays of umbel, 5–8 x 3–5 mm; surface green, longitudinally striate; thick-walled. P. villosa: Contarinia pimpinellae

5a Galls- bulging, soon bearing sori of rust fungi => 6

5b Galls as small, closed warts on the leaf axis, also on leaflets and stems. P. major, saxifraga: Physoderma hemisphaericum

5c Galls elongate spindle-shaped, a few to several (15) mm long; glabrous, at first vitreous, yellow-green, then ± browned. On the veins and axis of leaves, also on stem parts, usually close to ground. Many spores close to vascular bundle. P. major, saxifraga: Protomyces macrosporus

6a Galls bearing countersunk aecia and spermogonia => 7

6b Ridges on leaves with variable long, yellow-margined slight bulges, from which erupt cinnamon-to dark brown telia. P. major, siifolia: Puccinia corvarensis

7a Expanded or smaller, ± spindle-shaped, yellow bulges on petioles, midrib, leaf veins; occasionally on young stems; bearing pale yellow, pustule-shaped opening aecia. Peridium not or slightly protruding, if so then glossy white and irregularly frayed. Pimpinella spp.: Puccinia pimpinellae

7b Bulges similar, but usually smaller and more strongly swollen, often vivid reddish-yellow. Aecia deeply countersunk, sometimes remaining enclosed by tissue, globular or flat, not cup-shaped. Peridium not protruding. P. anisum, major, peregrina, saxifraga: Puccinia bistortae species complex.

8a Malformations on leaflets, with or without involvement of midrib => 9

8b Leaf sheath, especially close to umbel, inflated, bulging and swollen, succulent, often lacking leaf blade, enclosing the etiolated side shoot, sometimes inducing a cone-shaped acuminate gall. Larvae orange-red. P. major, saxifraga: Jaapiella hedickei

8c Occasionally, in very similar malformations, on P. major, peregrina, saxifraga, also develops: Semiaphis pimpinellae

9a Malformations affect leaflet leaf blades as well as leaf midrib => 15

9b Malformations on leaf blades, usually without stunting of midrib => 10

10a Leaf blades folded, as in buds => 12

10b Malformation on at least partially ± unfolded leaf blades => 11

11a Apart from often only a few normal leaflets, many are rolled at margin, thickened, ± frayed, twisted and distorted, weakly pubescent. P. major, saxifraga: Aceria peucedani

11b Leaf blades that are infected during their development show pale-green, weakly inflated upward arches, covered on underside with a dense cover of white conidiophores. P. major: Plasmopara nivea

12a Rolls or folds of leaflets => 14

12b Halves of leaflets do not unfold => 13

13a The folded leaf blade is ± shortened and curled, discoloured close to the midrib. White larvae develop between the ± distinctly thickened folds. P. major, saxifraga: Macrolabis sp.

13b Similar gall, but midrib usually bent and thickened: Contarinia sp.

14a Leaflets longitudinally rolled upwards, ± thickened. White midge larvae inside. P. saxifraga: Unidentified gall midge

14b Leaflets curled upwards or folded. Galls sometimes ± yellowish, also reddish, transversely undulate and partially twisted. P. major, peregrina, saxifraga: Semiaphis pimpinellae and/or Hyadaphis foeniculi

15a Malformations caused by aphids or psyllids => 16

15b Midrib over the tip or laterally ± conspicuously bent, with accordingly clustered, curled, deflected, locally deep green leaflets. P. anisum, major, saxifraga: Philaenus spumarius

16a Midrib of young leaves stunted. Leaf segments deflected, ± curled, slightly discoloured; with black aphids on underside. P. anisum, major: Aphis fabae

16b Leaf segments ± deflected at margin, with protrusions up to 5 mm wide, not discoloured, usually on upper side. Midrib of infected developing leaves severely stunted. P. anisum, major: Trioza apicalis s. l.

17a On flowers or fruits => 22

17b On ± expanded parts of inflorescence => 18

18a Malformation of large parts or complete inflorescence => 19

18b Centre of umbel or stalk of umbel ± swollen, club-shaped. Inner wall lined with mycelium. Containing a red larva. Pimpinella spp.: Lasioptera carophila

19a Malformations caused by aphids or thrips => 20

19b Inflorescence ± stunted, flower parts, usually with exception of aborted ovaries, greening and leafy. P. major, saxifraga: Aceria peucedani

20a Malformations associated with variously stunted axial parts or clustering of umbels. Sheaths of bracts usually ± swollen, bladder-like, and discoloured violet-red. Flowers undeveloped or ± greened; caused by aphids => 21

20b Gall-like malformations on flower buds or flowers caused by froth-covered nymphs or by very agile adult thrips. P. saxifraga: Unidentified thrips

21a Aphid green. P. major, peregrina, saxifraga: Semiaphis pimpinellae

21b Aphid black. P. saxifraga: Aphis fabae

22a On fruits => 24

22b Flowers globular, swollen, unopened => 23

23a Galls on P. saxifraga, rarely on P. major, ± globular, often reddened. Containing a sulphur- or lemon- yellow jumping midge larva: Diodaulus traili

23b On P. major, rarely on P. saxifraga. Larvae dark orange-coloured, jumping: Contarinia umbellatarum

24a Usually only one mericarp strongly inflated, bladder-like; distinctly protruding from the umbel. Wall thin, often reddened. Containing 1 (2–3) orange-red larvae. P. anisum, major, saxifraga, tragium: Kiefferia pericarpiicola

24b Young fruits slightly disfigured, shortened, rounded; mericarps not splitting up; containing pale brown-red or yellowish olive-coloured smut spores. P. saxifraga: Thecaphora pimpinellae

1a On parts above ground => 2

1b Main- and side roots with conspicuous, spindle-shaped, succulent, compact galls with length of 2–15 mm. |”Clubroot”. C. amara, parviflora, pratensis: Plasmodiophora brassicae

1c Small, half globular or irregularly shaped galls on root collar at base of basal leaves, caused by beetle larvae. Cardamine spp.: Ceutorhynchus minutus

2a Malformations caused by fungi fruiting at surface => 17

2b Malformations caused by animals or by fungi fruiting inside gall => 3

3a On flowers, fruits, and their stalks or on vegetative axillary buds => 13

3b On leaves or stems => 4

4a On stems, leaf base or on veins => 7

4b Galls exclusively or predominantly on leaf blades => 5

5a Leaf blade with grooves or warts => 6

5b Axis of leaflet stunted, leaflets clustered; leaf blades folded or (especially if leaf blades undivided), strongly rolled upwards. Leaf blades wrinkled, green, in many species additionally haired. C. alpine, bellidifolia, bellidifolia, hirsuta, impatiens pratensis, resedifolia: Aceria drabae

6a Leaf blade with scattered small grooves. C. amara, flexuosa, hirsuta, impatiens, opizii, uliginosa: Trioza rotundata

6b Leaf blades with many warts, on underside ± half globular protruding, golden-yellow translucent, less than 1 mm long; also on leaf midrib and -stalk, as well as on lower stem parts; sometimes coalescing crust- or ridge-like. C. amara, pratensis: Synchytrium aureum

7a Galls on stems, leaf base or rachis; inducer inside gall => 9

7b Malformation of stem by parasites on outside => 8

8a Stem swollen over variable length, on rind with ± rimmed, flat depressions, each containing a froth-covered nymph. C. glauca: Planchonia arabidis

8b Axial parts stunted and curved; neighbouring leaves clustered. Containing a froth-covered nymph. Cardamine spp.: Philaenus spumarius

9a Swellings glabrous; containing midge- or beetle larvae => 10

9b Shoot- or also leaf axis severely stunted, often spongy and swollen on all sides, if one-sided, then often associated with curving; galls pale green, with wrinkled surface. C. hirsuta, pratensis: Ditylenchus dipsaci

10a Galls slender, ± spindle-shaped or elongate; caused by beetle larvae => 12

10b Galls compact, oval or ± barrel-shaped => 11

11a Petiole at base, including neighbouring stem tissue, strongly swollen. Axial buds severely stunted, hardly enlarged. Caused by midge larvae. C. amara: Dasineura cardaminicola

11b Single galls ± barrel-shaped, often on stem base, also on stalks or midrib of basal or lower leaves; occasionally in shorter or longer groups, often bulging, even coalescent, up to 15–30 mm long. Each gall contains a beetle larva. C. amara, hirsuta, impatiens, pratensis: Ceutorhynchus pectoralis

12a Stem at various sites usually with slender spindle-shaped swelling on all sides or more one-sided, then often ± curved, about 10–20 mm long; the fleshy tissue contains a larva inside. C. amara, hirsuta, pratensis: Ceutorhynchus pectoralis

12b From similar, but rougher galls on C. resedifolia has been reared Ceutorhynchus chalybaeus

12c Usually lower part of shoot axis, with one-sided weak swellings. Galls and upper stem parts often slightly curved. The rind layer with narrow feeding site, containing a beetle larva. C. amara, pratensis: Psylliodes napi

13a On flower peduncles, flowers or fruits => 14

13b Lateral buds disfigured. C. flexuosa, hirsuta: Dasineura umbrosa

14a Malformations on flowers or flower peduncles => 15

14b Malformations on fruits. Siliques shortened, hardly thicker than their stalk. Diseased parts of inflorescence further developing and flowering sporadically when the healthy parts are already bearing fruits. Anthers of diseased flowers ± disfigured, dirty grey-brown, covered, and filled with conidia. Young seed soon aborted and filled with bright brown spores. C. alpina, bellidifolia: Thecaphora thlaspeos

15a On flower buds or flowers => 16

15b Flower peduncle severely swollen at base. C. amara: Dasineura cardaminicola

16a Flower buds swollen. Calyx ± normal; corolla unopened, thickened at base, greened. Stamens shortened, bent and thickened. Containing several red larvae. C. amara, flexuosa, opizii, pratensis: Dasineura cardaminis

16b Flowers filled with stamens and ovaries changing into corolla leaves. C. pratensis subsp. paludosa, pratensis: Unidentified gall mite

17a Malformations covered by brown sori => 20

17b Malformations with white sori => 18

18a Sori consisting of loose down of branched conidiophores => 19

18b Sori pad- or bulge-like, compact, at first closed, glossy, porcelain-like, after rupturing mealy dusted; in variable expansion on ± swollen, sometimes arched parts on all green organs. Cardamine spp : Albugo candida

19a On the occasionally completely infected plants or rarely also on lateral short shoots all parts are stunted, pale green, slightly thickened, the leaf blade margins ± curved. Localised infestation of stems results in slight swellings and curvings. Underside of the leaves with a whitish down, consisting of erect conidiophores that apically are branching several times, each branch ending in a conidium. C. bulbifera, heptaphylla, impatiens, parviflora, pentaphyllos: Hyaloperonospora dentariae

19b Sori similar, usually more loose, on many plant parts, only exceptionally inducing gall-like malformations. C. amara, flexuosa, heptaphylla, hirsuta, impatiens, macrophylla, pratensis, trifolia: Hyaloperonospora parasitica

19c On Cardamine enneaphyllos,? glanduligera. Infection usually systemic, plants become dwarfed, stunted and chlorotic. Underside of the leaves with a whitish down, consisting of erect conidiophores that are dichotomously branching apically several times, each branch ending in a conidium: Hyaloperonospora cardamines-enneaphyllos

19d On C. graeca. Underside of the leaves with a whitish down, consisting of erect conidiophores that apically several times are dichotomously branching, each branch ending in a conidium: Hyaloperonospora malyi

20a Sori on the sometimes slightly swollen leaf midrib, also on stems, axis of inflorescence or fruits; bearing early naked, chestnut-brown, 2-celled telia. C. alpina, bellidifolia, pratensis, resedifolia: Puccinia cruciferarum

20b Smaller or expanded swellings, only later erupting, bulge-shaped, usually associated with strong curving and twisting, up to 25 mm long, at first grey, later on brown dusted; on all green parts and even occurring on pale subterranean shoot parts. C. bulbifera, enneaphyllos, glanduligera, heptaphylla, macrophylla: Puccinia dentariae

1a On above-ground plant parts => 2

1b Roots with nodule-shaped swellings. A. apennina, sylvestris, Hepatica nobilis, Pulsatilla vulgaris: Meloidogyne hapla

2a On stems, rhizomes, leaves and bracts (whorl of leaves on flower peduncle) => 5

2b On flowers and fruits => 3

3a On fruits => 4

3b Flower peduncle shortened. Flower sterile; pod atrophied, remaining on plant. Pulsatilla alpina: Unidentified gall mite

4a Fruit swollen at base, appendage abnormally pubescent, twisted. Containing yellow or reddish larvae. Pulsatilla pratensis, vernalis, vulgaris: Dasineura pulsatillae

4b Ovary or fruit disfigured. Larva yellow. Pulsatilla pratensis: Unidentified gall midge

5a Malformations of aerial parts, already displaying early sori => 15

5b Malformations without fruiting bodies at surface or bulges, rupturing later on and releasing dusting of spores => 6

6a Malformations restricted to less extensive plant parts => 7

6b Flowering or non-flowering plants usually conspicuously disfigured, in all parts ± greatly enlarged. A. nemorosa; also recorded from A. ranunculoides, trifolia: Virus disease

6c Aphids in early spring on the root collar and stem base; later on the leaves and finally on the developing fruits; no host plant alternation. P. vulgaris ssp.grandis, pratensis subsp. nigricans: Aphis pulsatillicola

7a Bulges conspicuous, often strongly arched or curved, soon translucent lead-grey, rupturing later on and releasing black dusting, or fungus sori brown, remaining closed => 14

7b Plant parts with small wart-shaped or ± expanded, pale green spongy or more compact, concave swellings, or leaf blades rolled, folded or bent => 8

8a Swellings wart- or bulge-like => 12

8b Leaf blade rolled, folded or bent => 9

9a Leaf blade ± narrowly rolled upwards => 11

9b Leaf blade folded or bent => 10

10a Tips of bracts folded, shortened. Midrib swollen, reddened. A. nemorosa: Unidentified dipteran

10b Leaf blades ± nest-like clustered downwards, bent. Containing a froth-covered nymph. A. sylvestris, Pulsatilla pratensis and several cultivated species: Philaenus spumarius

11a Single or all leaflets with loose, ±curled, rough upward roll; on younger leaves often including the major part of leaf blade. Rolls ± red coloured, sometimes twisting the leaf blade. Containing several yellow-red larvae. A. sylvestris: Unidentified gall midge

11b Leaf blades rolled upwards, sometimes ± twisted, screw-like. Anemone spp., Hepatica nobilis: Aphelenchoides fragariae

12a Galls expanded, usually ± bulging => 13

12b Small red- to black-violet warts, up to 0.5 mm long, often many and mainly on leaf underside. A. nemorosa, ranunculoides; less abundant on A. coronaria, sylvestris, Anemonoides seemenii, Pulsatilla alpina: Synchytrium anemones

13a Stem- or predominantly lower leaves spongy, swollen basally to varied extent. Surface of often pale green galls ± wrinkled. Parasites inside the galls. A. coronaria, x japonica, Hepatica nobilis: Ditylenchus dipsaci

13b Petiole or partially also rachis with an irregular spindle-shaped swelling, about 15–30 mm long, tough-walled, usually curved, having one or more depressions, containing the initially surface living gall causer. P. pratensis: Planchonia arabidis

14a Leaf blade with ± rotund bladder-like swellings of various size, protruding on upper side, more rarely on underside. Petiole, also stem, with distinctly protruding, sometimes curved, ± spindle-shaped bulges. Patches crust-shaped, initially often yellowish, soon dark-, later on black-brown; not opening. On A. sylvestris and other species. Galls 5, 6 to winter. Anemone sylvestris; Pulsatilla alpina, armena, halleri, montana, patens, pratensis, vernalis, vulgaris: Puccinia pulsatillae species complex

14b Sori conspicuous, lead-grey translucent, rupturing later on and releasing black dusting of spores; on the leaf blades rotund, usually bladder-like arched upwards; on leaf veins, -stalks and stems bulging, often accompanied by stronger curvatures; occasionally even on flower parts and on pale rhizome sections. The forms of this fungus occur on many anemones and belong to the former species complex. Urocystis anemones s.l.

a On A. apennina, nemorosa, ranunculoides and relatives: Urocystis anemones s.str.

b On A. baldensis, coronaria, sylvestris and relatives: Urocystis antipolitana

c On members of Hepatica, such as H. acutiloba, nobilis, transsilvanica: Urocystis syncocca

d On members of Pulsatilla, such as P. alpina, montana, patens, pratensis, vulgaris and relatives: Urocystis pulsatillae

15a Malformations with brown sporulating sori => 19

15b Malformations with lighter aecia and pycnidia => 16

16a Petiole conspicuously elongated, developing early. Leaf blades ± stunted; leaflets narrowed, usually less subdivided, slightly thickened, paler. Aecia scattered on the underside of leaf blade. Sometimes also ± partial but expanded infestation on flowering plants; sori then even on flowering parts. Mycelium perennial => 17

16b Sori on underside of leaves ± rotund, up to about 10 (15) mm broad, elongate-oval on veins and stalks, yellowish, often only slightly thickened. Hepatica nobilis, vulgaris: Puccinia actaeae-agropyri

17a Cups of aecia rupturing, with a few broad lobes => 18

17b On A. nemorosa. Cups whitish; peridium rupturing into many lobes. Copious, initially white, later on brownish spermogonia only on upper side. Membrane of aecia thickened at apical part: Ochropsora ariae

18a On A. ranunculoides. Peridium usually with only a few, 3–5 (6), broad lobes. Spermogonia already initially dark, on both leaf sides. Spore membrane thickened terminally: Tranzschelia pruni-spinosae

18b Aecia analogous; on severely disfigured leaves and shoots, sometimes also flower parts of ornamental anemones, such as A. blanda, coronaria, hortensis: Tranzschelia discolor

19a Mycelium and sori expanded. Diseased organs with longer stems, narrowed => 20

19b Mycelium restricted; sori compact, bulging, rotund on the underside of sometimes curled leaf blades; on distinctly thickened veins or stalks ± elongate spindle-shaped, sometimes coalescing into long ridges. A. altaica, ranunculoides: Puccinia singularis telia

20a Petiole ± elongate; leaf blades variously stunted, simplified, somewhat thickened; plants usually non-flowering. Leaf blades on underside, mainly towards margin with expanded areas of rotund, dusty sori of dark brown telia and black-brown pycnidia. Scattered also on flowering plants. Flowers stunted, disfigured. A. nemorosa, also on A. apennina, blanda, nemorosa, sylvestris, trifolia; Anemonoides seemenii: Tranzschelia anemones

20b Leaves usually longer stalked; leaf blade less expanded, narrower; sori dusting, expanded on leaf underside. P. alpina, halleri incl. subsp. styriaca, montana, patens, pratensis, vernalis, vulgaris: Tranzschelia pulsatilla

1a On parts of flowering or fruiting inflorescences => 21

1b On vegetative plant parts => 2

2a Malformations mainly of leaf segments => 13

2b Malformations mainly of stems, petioles and midrib or of venation of leaflets => 3

3a More or less spindle-shaped bulges caused by rust fung => 4

3b Spindle-shaped, vitreous, glabrous, yellowish-green, later brownish bulges on leaf axis and stem. Spores develop inside the galls. P. ostruthium, palustre: Protomyces macrosporus

4a Galls caused by mycelia developing uredinia or telia => 6

4b Galls caused by mycelia developing aeci => 5

5a Distinctly protruding swelling on leaf veins, -midrib or -stalks of P. ostruthium: Puccinia imperatoriae-mamillata

5b Similar malformations on P. rablense: Aecidium peucedani-raiblensis

6a Galls caused by primary mycelium developing uredinia accompanied by spermogonia. Sori with secondary uredinia or telia small, usually non-cecidogenic, often many on leaves, partially also on stems => 7

6b Fungus develops only telia on conspicuous, rather strongly swollen, rotund or elongated bulges on the leaf underside or on leaf axis. P. ostruthium: Micropuccinia imperatoriae

7a Fungi belonging to the Puccinia bullata species complex, distinguished by glabrous teliospores; morphologically partially ± similar but biologically usually distinctly different => 10

7b Teliospores covered with parallel running lines => 8

8a On P. oreoselinum or P. verticillare. Teliospores bearing loosely distributed warts => 9

8b On P. coriaceum, parisiense, ruthenicum, officinale: Puccinia rugulosa

9a On P. oreoselinum. The primary, cinnamon-brown uredinia develop on usually conspicuous, curved bulges on leaf venation, -midrib and -stalks: Puccinia oreoselini

9b On P. verticillare: Puccinia terrieri

10a On P. alsaticum, palustre, venetum => 12

10b On P austriacum, cervaria, rablense => 11

11a On P. austriacum. Malformations minor and rare: Puccinia peucedani-austriaci

11b On P. cervaria. Galls often conspicuous, on petioles and veins, up to 20 mm long, often curved, bearing spermogonia and primary uredinia: Puccinia cervariae

12a On P. alsaticum: Puccinia peucedani-alsatici

12b On P. palustre. Distinct swellings, up to several cm. long, on leaf veins, -midrib and -stalks, sometimes on stems: Puccinia semadenii

13a Leaflet with narrow marginal roll => 20

13b Leaflets with bulging swellings, curls or loose folds, or rolls of their margins => 14

14a Malformations with downwardly bent margins => 15

14b ip of leaflet folded upwards or rolled inwards, partially curled, thickened at base, discoloured ± yellowish to reddish. Containing white larvae. P. cervaria, oreoselinum: Macrolabis incognita and/or: Jaapiella buhri

15a Expanded malformations of leaf blades or conspicuously discoloured marginal roll, or fold => 16

15b Curling of tip leaflet. P. oreoselinum: Trioza sp.

15c On the leaves of P. ostruthium have been recorded the larvae of Trioza apicalis

16a Malformation caused by aphids or by surface fruiting fungi => 17

16b Leaf midrib sometimes stunted over large areas, bearing clustered, sometimes nest-like converging, locally deep green coloured leaves. Peucedanum spp.: Philaenus spumarius

17a Malformations caused by aphids => 18

17b Leaf blade pale green, swollen, bladder-like, mainly on upperside soon covered with loosely arranged fungal fruiting bodies. P. palustre: Taphridium umbelliferarum

18a Malformations on expanded leaf parts => 19

18b Terminal parts of leaflets partially or completely ± mussel-shaped, deflected downwards or loosely rolled, slightly thickened, conspicuously discoloured red and yellow. Aphid yellow to bright greenish-yellow. P. cervaria, oreoselinum: Semiaphis cervariae

19a On P. palustre. Severe stunting of midrib; leaflets, occasionally at terminal leaf part densely clustered, nest-like at tip and margin deflected: Semiaphis anthrisci

19b On P. officinale; colonising shoot tips and deforming leaves: Semiaphis horvathi

19c On P. ostruthium. Leaf blades rolled downwards or arched. Malformations sometimes expanded; leaves converged, nest-like:Semiaphis sphondylii

20a Tips of leaflets stunted, rolled at margin, ± twisted and discoloured. P. arenarium, palustre; Aceria peucedani

20b Similar malformations on P. oreoselinum: Unidentified gall mite

21a Malformations of large parts of inflorescence or galls locally on axial parts => 22

21b Fruit strongly inflated, bladder-like; galls ± reddened, protruding above the umbel; 1 (3) orange-red larvae: Kiefferia pericarpiicola

22a Malformation of expanded parts of inflorescence => 23

22b Centre of umbel or stalk of umbel ± swollen, club-shaped, sometimes also affecting the base of the stalks of umbels. Inner wall covered with mycelium. Containing a red larva: Lasioptera carophila

23a Inflorescences and ± greened flowers variously disfigured by aphids. P. palustre: Semiaphis anthrisci

23b Similar, often compact malformations caused by mites, often associated with severe greening and malformation of flowers. P. carvifolia, cervaria, oreoselinum, palustre, venetum: Aceria peucedani

1a On above-ground parts => 2

1b Roots with nodular swellings. J. communis: Meloidogyne sp.

2a On fruits => 28

2b On vegetative plant parts => 3

3a On terminal shoots, shoot tips or only on leaves => 13

3b On lower axial parts of shoot => 4

4a Shoot axis with tuberose- or elongated swellings of various length => 5

4b Bark of younger shoots with, rimmed depressions, up to 2 mm long, containing inducer. J. communis: Carulaspis juniperi

5a Elongate galls without larval cavities, at maturity with fungal structures at their surface => 9

5b Similar galls, but with tunnels caused by of lepidopteran larvae feeding => 6

6a Caterpillar white to reddish => 7

6b Caterpillar pale brown, head black, neck- and anal scale brown. J. communis: Chionodes electella

7a Caterpillar usually uniform white => 8

7b Caterpillar dirty white, often reddish tinged; head and neck scale brown. J. communis: Cydia duplicana

8 Caterpillar biannual, ivory white. J. communis: Synanthedon cephiformis

8b Caterpillar annual, whitish. J. communis: Synanthedon spuleri

8c The so-called “tuberculate disease” in twigs of Mediterranean J. communis, phoenicea as well as on Cupressus sempervirens has been attributed to: Ceratostoma juniperinum

9a Spindle-shaped to elongated cylindrical swellings of twigs and branches. Telia partially thick-, partially thin-walled, dark to pale, on ± long stalks; sori united under humid conditions into gelatinous swollen columns, tongues or pads; uredinia absent. In spring, on J. communis and relatives => 11

9b Similar galls on J. sabina and relatives. Sori of telia cornicular, thick, usually higher than wide. Telia oval to short, spindle-shaped => 10

10a Sori brown-red to chestnut brown, at first pad-shaped, then developing yellow-brown blunt-conical lobes. Galls with perennial mycelium, spindle-shaped, 6–8 cm long. Juniperus spp.: Gymnosporangium confusum

10b Sori black-brown to black. Galls with perennial mycelium, when mature about 10 (12) cm long and 3–4 cm thick. Juniperus spp.: Gymnosporangium sabinae

11a Sori flat cushion-shaped, much broader than high, swelling to a mussel-shaped body. Telia oval or short spindle-shaped, hardly twice as long as broad, partially thick-, partially thin-walled => 12

11b Sori cylindrical, band- or tongue-shaped, up to 5 mm long, 2 mm thick, orange-coloured; swelling to a pale yellow compact jelly-like body when wet, clustered on slender spindle-shaped swelling of stem parts sometimes bent, perennial. Telia oblong-spindle-shaped. Juniperus spp.: Gymnosporangium clavariiforme

12a Dry sori forming flat brown, 1–2 mm high, up to 5 mm broad and 20 mm long pads, which swell to orange-coloured, mussel- or cup-like extending jelly bodies if humid. Swellings often little pronounced; mycelium soon withering. Juniperus spp.: Gymnosporangium tremelloides

12b Witches’ broom on J. oxycedrus, microcarpa: Gymnosporangium gracile

12c Sori usually smaller, developing into yellow-red discoloured jelly bodies; distinguished by its smaller spores. Galls usually on thinner twigs as weak spindle-shaped swellings. Sori also on needles: Gymnosporangium cornutum

= In addition, a rust gall, caused by Gymnosporangium asiaticum has been recorded on introduced J. chinensis

13a On shoot tips => 17

13b On leaves => 14

14a Bulging or tongue-shaped malformations on terminal part of needles, caused by fungi => 15

14b Basal part of needle bulging, swollen. Internodia ± shortened. J. communis, etc.: Trisetacus juniperinus

15a Spores brown, predominantly 2-celled, in gall-like sori; swellings ± compact, slightly bulging => 16

15b Spores black, 1-celled in 3–6 mm long severely blister-like arched dusty sori. J. communis: Lepidoderma carestianum

16a Two-year to perennial needles on upperside with small, slightly arched, lacerate, cinnamon- to black-brown sori, also containing, apart from 1-celled ± globular brown uredinia, 2-celled teliospores, ± egg-shaped, slightly constricted in the middle. J. communis: Gymnosporangium gaeumannii

16b Similar, usually only pinhead size jelly bulges, macroscopically hardly different from previous fungus, containing only 2-celled teliospores. J. communis: Gymnosporangium cornutum and/ or Gymnosporangium tremelloides

17a Galls on tips of shoots => 19

17b Malformation of many leaves terminally on stunted shoots => 18

18a Dense accumulation of almost imbricated covered needles at top of young stunted shoots. J. communis: Cause unknown – ? aphid

Many needles accumulated at the end of a shoot; swollen at base, bulging. J. communis, chinensis: Trisetacus juniperinus

19a More or less bud-like galls caused by gall midges. On J. communis => 21

19b Similar galls on J. sabina => 20

19c Pear-shaped galls with blunt apex on J. oxycedrus, navicularis 10–12 mm long and 8–10 mm wide at base formed by an atrophied brownish inner whorl of needles enclosing a larval chamber and an outer whorl of very broad thickened needles, fused at base and slightly shortened. Containing a single larva: Oligotrophus valerii

20a Pyramid-shaped gall, up to 13 mm long and 5 mm broad, at base gradually narrowing, consisting of 3–5 (7) distinctly enlarged pairs of acuminate leaves; back of leaves rounded and weakly carinate. J. sabina, phoenicea: Etsuhoa sabinae

20b Gall consisting of several pairs of leaves, up to 5 mm long, rotund, strongly shouldered at base. Leaves thickened, their back with deep furrow. Containing a single larva. Unidentified gall midge

21a Gall is composed of two or more whorls of needles => 22

21b The small gall, up to 3 mm long, is oblong-egg-shaped and consists of only one whorl ± distinctly shortened, broadened, mutually covering leaves. Containing a single orange-coloured larva. J. communis: Oligotrophus gemmarum

22a Galls always composed of only two whorls => 25

22b Galls composed of (2) 3–4 whorls => 23

23a Galls larger than 5 mm => 24

23b Gall consists of 2–4 whorls, egg-shaped to conical, small, occasionally up to 4 mm long; outer needles scale-like broadened, composing a closed gall. Galls sometimes also in the male inflorescences. Unidentified gall midge

24a Gall composed of 3–4 whorls, up to 10 mm long, oblong, ± acuminate, terminally on main- and lateral shoots. Needles of the outer whorl ± shortened and distinctly broadened, those of the second whorl slightly longer, but narrower, the inner becoming narrower and smaller, enclosing the central larval chamber. At maturity of the gall, the needle tips are usually outwardly deflected. Containing an orange-coloured larva. J. communis: Oligotrophus sp.

24b Similar galls, containing single red larvae when mature. Unidentified gall midge

25a Needles of the outer whorl ± open or outer whorl spreading at least at maturity of gall => 26

25b Gall up to 12 mm long; ± slender conical, acuminate. Needles of the outer whorl only broadened in the basal half the upper half narrowed, enclosing completely the inner whorl of shorter, narrower needles. Containing a single orange-coloured larva. J. communis: Oligotrophus panteli

26a Galls at most 6 mm long => 27

26b Up to 12 mm long, oblong, not acuminate gall. Needles of the outer whorl broadened and thickened over their whole length. Needles of the inner whorl narrow, adpressed. Leaves of the outer whorl spreading distally at maturity. Containing a single orange-coloured larva. J. communis: Oligotrophus juniperinus

27a Gall often acuminate, up to 5 (6) mm long, ± discoloured. Needles of the ± open outer whorl mainly broadened at base, terminally distinctly narrowed, sometimes deflected outwardly, shorter than inner ones, composed of a closed whorl of converging narrow leaves. containing a red larva. J. communis: Oligotrophus schmidti

27b Open, up to 5 mm long, rarely larger gall, in which the distinctly broadened leaves of the ± spreading outer whorl are as long as, or shorter than the closed inner whorl, usually blunt- to acute-conical gall body. Containing a single red larva. Oligotrophus sp.

28a Fruit slightly swollen, slightly stunted; flesh hypertrophied, carpels incompletely fused, composing at the top a three–rayed opening. Seeds usually sterile, visible under the slits. J. communis: Trisetacus quadrisetus

28b Fruit with grooved, rimmed depressions. J. communis: Carulaspis juniperi

1a On extensively elongated stems, on buds, leaves or flowers => 2

1b Basal shoots severely stunted and transformed into a large cone-like tough, fleshy gall several cm long, reddish-grey, multi-chambered and bearing rotund lumpy proliferations. Similar but smaller galls also on petioles. F. ulmaria, vulgaris: Dasineura harrisoni

2a On inflorescences or flowers => 20

2b On vegetative parts => 3

3a Galls on stems, midrib of leaf, leaf veins or -blades, caused by animals => 10

3b Shoot axis, petiole or leaf veins with many wart-shaped nodules or with extended swellings; fungus galls => 4

4a Expanded malformations caused by rusts, smuts or mildews => 6

4b The young, still developing parts bear many wart-like galls, hardly 1 mm across, loosely arranged or ± expanded into coalesced crusts => 5

5a Warts consisting of several cells. F. ulmaria, vulgaris: Synchytrium aureum

5b Galls 1-celled, only known from F. ulmaria: Synchytrium ulmariae

6a Galls covered with orange-red spore masses, or also at first unopened with lead-grey translucent blackish spores dusting later on => 7

6b Malformations caused by a white mycelium growing on outside of host. F. ulmaria: Podosphaera aphanis

6c Similar malformations; stems, leaves and shoots thickened and sometimes twisted or otherwise distorted, covered with thick, white mycelium. F. kamtschatica, ulmaria, vulgaris: Podosphaera filipendulae

7a Galls soon covered by orange-red rust sori => 9

7b Galls caused by smuts with spores 1–8 united in easily degraded balls, enveloped by sterile auxiliary cells => 8

8a On F. ulmaria: Urocystis ulmariae

8b On. F. vulgaris: Urocystis filipendulae

9a On F. ulmaria, lobata and relatives: Triphragmium ulmariae

9b On F. vulgaris: Triphragmium filipendulae

10a Large parts of leaf blades disfigured or with localised galls => 13

10b Stems, leaf midrib or leaf veins with localised galls => 11

11a Galls on leaf midrib or leaf veins => 12

11b Weak thickening of shoot axis, mainly close to ground. F. ulmaria: Unidentified lepidopteran

12a Galls hemispherical on upperside, protruding on underside acuminate- conical; wall soft; on midrib or main veins; upperside glabrous and often reddish, underside yellowish, ± pubescent, with terminal, pubescence, narrow exit hole, one-chambered. Containing a single whitish-yellow larva. F. lobata, ulmaria: Dasineura ulmaria

= Various aberrant galls have been described in literature; attributed to either D. ulmaria or undescribed other gall midges. D. harrisoni causes on F. ulmaria in various wet biotopes expanded galls close to the ground.

12b Galls only conspicuous on one side of leaf. Midrib of leaf blade swollen. F. ulmaria: Epitrimerus filipendulae

13a Malformations on leaf blade of leaf => 14

13b Leaf blade deeply dissected at margin, indented, teeth ± narrow fimbriate. F. ulmaria: Unidentified gall mite

14a Leaf blade curled or otherwise extensively disfigured => 16

14b Small grooves or erinea on otherwise unchanged leaf blade => 15

15a On the underside of the slightly disfigured leaf blade occur 1 mm deep grooves in rotund, pale green spots, yellowish margined up to 5 (6) mm across with corresponding archings on upperside. Often many per leaf blade, sometimes coalescing. Each containing a single vitreous, white to greenish larva. F. ulmaria, vulgaris: Dasineura pustulans

= Small grooved galls on F. ulmaria, arched on upper side, which display eggs in the underside cavity, have been attributed to an unidentified psyllid, which may, in strong infestations, also cause a ± distinct curl or upward roll of the leaf margin.

15b On leaf underside between veins, usually close to margin irregular erinea of various dimension with white, club-like hairs. F. ulmaria: Unidentified gall mite

16a Curling or rolling of leaf blade, caused by aphids or spittlebugs => 18

16b Leaf blade with buckled archings or folds, caused by gall midges => 17

17a Bulging yellowish-green to often reddish folds or swellings of the leaf blade, usually elongated and bumpy, often coalescing. Development varies. In cases of strong infestation the leaf blade is strongly curled; occasionally at margin with thickened rolls. Each depression on the underside containing a larva that is at first white, then pale red. F. lobata, ulmaria, vulgaris: Dasineura engstfeldi

17b Leaf blade folded downwards along a lateral vein, white larvae on upper side. F. ulmaria: Dasineura engstfeldi

18a Malformations caused by aphids => 19

18b Shortening of leaf midrib and curling of leaf blade. Filipendula spp.: Philaenus spumarius

= Spiral rolls of stunted basal leaves. The leaflets are densely clustered on the stunted midrib. On the midrib occur bluish-grey, black-headed larvae of an unidentified sawfly

19a Weak arching or curling of leaf tip. F. ulmaria, vulgaris: Macrosiphum cholodkovskyi

19b Various expanded curvings, folds, rolls. F. ulmaria, vulgaris: Aphis ulmariae

20a Flower galls => 22

20b Malformations of inflorescence => 21

21a Often conspicuously disfigured inflorescence covered with a white mycelium: Podosphaera aphanis

21b Stalks of inflorescence distinctly shortened. Buds, and flowers therefore clustered. F. ulmaria, vulgaris: Aphis ulmariae

21c Malformations are also caused by froth-covered nymphs of
Philaenus spumarius

22a Flowers unopened, containing midge larvae => 23

22b Galls on buds and stems of the midge that usually lives on leaves have been attributed to Dasineura ulmaria

23a On F. ulmaria. Flowers swollen on one side in an irregular manner, here densely pubescent, discoloured pale to dark-red; stamens and stem etiolated, galled flowers 1.5–2 mm across, distinguished from healthy flowers by their small size. Larvae white, pale red later on: Dasineura engstfeldi

23b On F. ulmaria. Slightly swollen, unopened red-violet discoloured flower buds: Dasineura spiraeae

23c On F. hexapetala, vulgaris. Flowers unopened, swollen and ± reddened. Larvae red: Dasineura filipendulae

1a On parts above ground => 2

1b Side roots with smaller egg-shaped nodules, about 7 mm long, cylindrical or terminally broadened and branched to coralloid: Rhizobium leguminosarum

2a On inflorescences, flowers or fruits => 17

2b On vegetative organs => 3

3a Malformations caused by mycelium of rust fungus bearing aecia and telia => 16

3b Malformations by animal causers => 4

4a On leaves => 11

4b On buds, shoots, stems or thorns => 5

5a Galls on stems or thorns => 8

5b Galls on shoot tips or lateral buds => 6

6a Malformations with ± conspicuous abnormal pubescence; on small-leafed Astragalus species => 7

6b Tip of main shoot or of ± stalked side shoots severely stunted. The still unfolded vegetative or also generative parts restricted in further development and completely stunted, ± thickened. The marginal leaves in all basal parts swollen, towards the exterior increasingly unfolding, the free part partially towards midrib rolled inwards or also folded and strongly narrowly curled. In the middle of the malformation are several white larvae. A. glycyphyllos: Contarinia sp.

7a Shoot tip or lateral bud as result of ± expanded thickening of stipules, petioles and leaflets transformed into a whitish densely pubescent, rotund, tuft-like mass. A. arenarius: Unidentified gall midge

7b Top of main- and side shoots severely stunted; younger organs clustered into a rotund to egg-shaped ± closed gall. The marginal leaves ± stunted, all parts close to gall thickened, pale green and more pubescent, at their tips sometimes almost normal. The centre of the gall contains a single orange-yellow larva. A. danicus: Dasineura rossi

8a Single galls ± spindle-shaped, sometimes clustered into conspicuous irregular nodular structures => 9

8b Galls globular or barrel-shaped, acuminate, about 3–5 mm across, with thick, compact, glabrous wall. Containing a single or several larvae. Inducer unidentified – ? gall midge, ? eulophid chalcid

9a All-sided spindle-shaped galls on stems => 10

9b Galls usually one-sided on internodes, spindle-shaped to oblong-oval, about 4–6 mm long and 2 mm wide, bulging, pale green or browned; chambers in woody part, each contains a single larva. Galls usually with several per internode, sometimes closely alongside or behind one another and coalescing. Close to nodes usually densely clustered, conspicuous, ± oblong, sometimes consisting of almost all-sided brown-tubercular gall complexes, measuring 10–25 mm in length and 10–15 mm in width. A. arenarius, cicer, glycyphyllos: Inducer unidentified – ? gall midge, ? eulophid chalcid

9c Stem galls of various size on A. glycyphyllos, up to even finger size, as well as about cherry-sized axillary galls on A. arenarius which on this host contained several yellow midge larvae in a large central cavity: Dasineura astragalorum

9d Large galls on stems. A. lagurus: Asphondylia anatolica

10a Stem with all sided swelling, regular, wide spindle-shaped, tough- and thin-walled. A large chamber in pith containing several white chalcid larvae. A. danicus: Inducer unidentified – ? gall midge, ? eulophid chalcid

10b Stem close below the top swollen bottle-shaped; inside a cavity contains several white larvae. A. alpinus: Inducer unidentified – ? gall midge, ? eulophid chalcid

11a Malformations on leaflets or without conspicuous malformation of axial parts => 13

11b Galls mainly on petioles or midrib => 12

12a Petioles mainly at base often with several, usually separated, hard, spindle-shaped to oblong-oval one-chambered swellings, about 3–4 mm long. Containing a single larva. A. exscapus. Inducer unidentified – ? gall midge, ? eulophid chalcid

12b Leaf midrib stunted; leaflets clustered, along midrib and base thickened. A. alpinus: Dasineura cf. viciae

13a Leaflets folded upwards pod-like => 14

13b Leaf blades of leaflets rolled downwards. A. alpinus, arenarius, glycyphyllos: Aceria astragali

14a On A. danicus, exscapus, frigidus => 15

14b On many other Astragalus species. The leaflets of younger leaves are completely galled, strongly thickened and ± pale green, also reddish. In older leaves sometimes only some leaflets are distorted, in large-leafed species with only locally pod-like swellings, remaining with a ± broad margin of normally developed leaf blade; the leaflets may also be rolled upwards and thickened at margin. Older leaves brownish-yellow. A. cicer, glycyphyllos, monspessulanus: Dasineura glyciphylli

14c Inflated, yellowish green leaflets or terminal swellings on young stems. A. alpinus: Dasineura berti

14d Pod-like folded leaflets on A. lusitanicus: Dasineura mariae

15a Single or all leaflets of larger leaves pod-like, rolled upwards, strongly thickened, pale green or reddened. Each gall contains an orange-yellow larva. A. danicus, onobrychis: Dasineura rossi

15b Pod-like folded leaflets on A. lusitanicus: Dasineura mariae

15c Inflated, yellowish green leaflets or terminal swellings on young stems. A. alpinus: Dasineura berti

16a Mycelium perennial; leaves of infected shoots disfigured, shorter and tougher than the healthy ones. Often completely covered with telia on underside. A. frigidus: Uromyces phacae-frigidae

16b Shoots completely infected with mycelium, made conspicuous by its pale colour, all parts ± etiolated. Aecia mainly on underside, often completely affecting all leaf blades; III often also on leaf midrib and -stalks. A. alpinus, australis, frigidus; also on Oxytropis: Uromyces lapponicus

16c Similar malformations on A. leontinus, norvegicus. Spermogonia absent: Uromyces splendens

17a On inflorescences or on single flowers (for spindle-shaped galls on stalk => 18

17b Fruit hardly swollen, shortened, disfigured. Containing a single larva. A. asper. Asphondylia sp.

18a Single or several flowers disfigured => 19

18b Developing young inflorescences severely stunted; their stalks ± thickened. Flower buds variously swollen, globular, arranged in ± dense balls. A. glycyphyllos: Contarinia sp.

18c Usually all flowers of several inflorescences are already disfigured in bud stage and slightly swollen. Ovules at first swollen, later on filled with masses of red-brown spore balls: Thecaphora affinis

19a Flowers swollen, unopened; with midge larvae inside => 20

19b Flowers disfigured, containing a larva with head capsule. A. arenarius, austriacus, cicer, danicus, glycyphyllos, onobrychis, sempervirens: Mesotrichapion punctirostre

19c Similar malformations on A. glyciphyllos, varius, virgatus contain larvae of Pseudoprotapion astragali

20a Calyx strongly swollen, almost enveloping all organs. Corolla shortened, thickened, greened. Stamens and ovaries mostly moribund. Containing several orange-yellow larvae. A. arenarius, austriacus: Contarinia sp.

20b Similar galls, but with a dense layer of mycelium inside. A. glycyphyllos: Asphondylia sp.

1a Galls on restricted organs and parts of organs => 3

1b Malformation of expanded parts of the above-ground plant => 2

1c Red midge larvae living on roots. Schedonorus pratensis: Lasioptera auricincta

1d Roots with aphids. Festuca spp.: Tetraneura caerulescens

2a Complete plant stunted, only a few cm high; shoots at base onion-like, swollen. Leaf sheaths accordingly shortened, weakly swollen and broadened. Schedonorus pratensis: Chlorops sp.

= In severely stunted, over expanded spongy, swollen areas of young plants the polyphagous stem eelworm Ditylenchus dipsaci has occasionally been found.

2b Complete plant stunted. Upper leaf sheath distinctly widened, transversely folded and bulging. F. rubra: Unidentified tarsonemid mite

= Malformations attributed to the polyphagous mite Steneotarsonemus spirifex has been reported by for several fescues.

3a On above-ground plant parts => 4

3b Roots with swellings about 0.5–3 mm long, slender, screw-shaped or crooked. Festuca ovina, Schedonorus pratensis: Subanguina radicicola

= Also the cyst developing oat eelworm Heterodera avenae has been recorded on fescue

4a On leaves, inflorescences or flowers => 11

4b On culms => 5

4c Node of stem rarely swollen, encircled by fungus stroma, yellowish when mature; several nodes may be affected; flowering stunted; stroma containing narrow asci and filamentous spores. Festuca rubra: Epichloë festucae

5a Larvae are inside the galls => 10

5b Larvae between culm and leaf sheath => 6

6a Larvae in shallow covered depressions of the culm near the leaf sheaths => 7

6b Shoot severely stunted. Inflorescence often largely hidden in sheath. Culm at base of inflorescence sometimes ± swollen. Containing a single larva. Festuca rubra, Schedonorus arundinaceus, pratensis: Oscinella frit

= On Festuca rubra, Schedonorus pratensis lives the similar Oscinella vastator. On F. rubra, O. nitidissimaoccurs. On the culms of Schedonorus arundinaceus subsp. orientalis and Schedonorus pratensis, the closely related polyphagous Oscinella pusilla, and on Schedonorus arundinaceus, giganteus, pratensis, also recorded from Leymus, the widely distributed rarer Oscinella festucae

= On Festuca ovina, rubra stem galls incorporating leaf sheaths have been reported caused by Tetramesa brevicornis.

7a Depressions not conspicuously discoloured => 8

7b Black-coated, one-sided, expanded, irregular depression with orange-yellow larva, usually above the last node. F. rubra: Hybolasioptera fasciata

8a Depressions evenly weakly rimmed all around => 9

8b Depression particularly saddle-like, thickened at the ends, single or with several above the higher situated, predominantly last node. Each gall containing a bright red larva. Schedonorus pratensis: Haplodiplosis marginata

9a One to several laterally hardly swollen depressions of the culm. Each containing a single larva. Schedonorus arundinaceus: Lasioptera calamagrostidis

9b Base of young shoots sometimes, if many larvae or puparia present, slightly swollen. Larvae yellowish-white, ± 3 mm long; puparia flax seed-like; within a leaf sheath. F. rubra: Mayetiola festucae

10a Galls tapering at both ends, spindle-shaped, wall rugose, surface glabrous. Festuca spp.: Tetramesa brevicollis

10b Irregular, yellowish-green swellings of culm above the nodes. Festuca spp.: Tetramesa longicornis

11a Malformations on inflorescences, flowers or young fruits => 16

11b Malformations on leaf sheaths or -blades => 12

12a The malformations extend over substantial parts of the leaf => 13

12b Leaf blade with 1–2 mm broad, slender egg-shaped to bulging swellings, mainly on underside, often discoloured red- to blue-violet. Festuca spp.: Anguina graminis

= From Festuca ovina, rubra, Schedonorus pratensis the sac fungus Dilophospora alopecuri, which is associated with eelworms on several grasses, has been recorded.

13a Stripes caused by black-sporulating smut on leaf blade, occasionally also on sheath => 14

13b Malformations caused by aphids. Leaf sheaths ± bulging and swollen, leaf blades variously twisted and rolled inwards. Schedonorus pratensis: cf. Rhopalosiphum padi

14a Spores single => 15

14b Spores single or more rarely 2–3 in balls enveloped by sterile auxiliary cells. F. ovina, rubra: Urocystis ulei

15a Stripes of smut very long, fine; at first lead-grey, then yellowish-grey. Spore mass black-brown. Spores globular to rotund-oval, 20–30 x 18–24 μm. Wall yellowish-brown, with lighter patches. F. ovina: Tilletia sterilis

15b Patches of smut long, linear. Mass of spores almost black. Spores globular to rotund-oval, 10–16 x 8–14 μm; densely covered with small blunt warts. Festuca spp.: Ustilago festucarum

16a Malformations mainly on large parts of the inflorescence => 17

16b Single or several ovaries per inflorescence are distinguished by a pronounced bottle- or tube-shaped, often purple-red elongation; containing eelworms. Festuca spp.: Anguina agrostis

16c Red midge larvae develop in florets and seed cases without inducing galls. Festuca rubra, Schedonorus arundinaceus: Dasineura festucae

17a Stem parts of the exposed panicle shortened apically, or over the whole inflorescence, bearing ± disfigured flowers or spikelets. Festuca spp.: Aceria tenuis

17b Gall midge larvae live in the inflorescences. Festuca rubra, Schedonorus arundinaceus: Contarinia festucae

1a Galls only on flowers or fruits => 23

1b Malformations on vegetative organs => 2

2a Buds thickened, not opening; or galls only on leaves => 15

2b On leaves, ± including shoot axis or on shoot axis and sometimes additionally on axis of inflorescence => 3

3a Malformation of several leaves terminally on young, ± stunted shoots, caused by aphids => 11

3b Witches’ broom -like malformations or localised galls on various parts => 4

4a Conspicuous, ± expanded thickenings and distortions caused by scale insects or rust fungi => 5

4b Buds on woody parts developing into several short shoots, which in turn develop many lateral buds, which are severely stunted. Witches’ broom-like malformations. R. cathartica: Unidentified gall mite

4c On Frangula alnus and Rhamnus cathartica have been reported: Viscum album

5a Galls caused by rust fungi => 6

5b Bark of young axial parts swollen, with rimmed depressions, each containing a flattened froth-covered nymph under a pear-shaped scale. Frangula alnus; Rhamnus alpina subsp. fallax: Chionaspis salicis

6a Young shoot axis with variously curved, yellowish swellings, up to several cm long. Similar, ± spindle-shaped smaller galls on petioles and leaf veins; ± rotund swellings on leaf underside, on calyx, greened flower parts or on young fruits. On R. alpina, pumila, saxatilis, also on cultivated introduced species => 7

6b Similar malformations on Frangula alnus; Rhamnus alaternus, alpina, cathartica, lycioides subsp. graeca, pumila, saxatilis; species-complex of Puccinia coronata

7a Swellings bearing aecia on R. alpina, pumila, saxatilis => 8

7b On Frangula alnus: Puccinia coronata

8a Aecia on R. alpina, pumila => 10

8b Aecia on R. saxatilis => 9

9a Fungus alternating with several grasses; telia apically with lateral or upwardly directed appendages; species-complex of Puccinia coronata

9b Fungus alternating with Sesleria albicans. Telia without appendages: Puccinia sesleriae

10a Aecia recorded on R. alpina in the Alps:

a uredinia, telia mainly on Calamagrostis varia: Puccinia alpinae-coronata

b uredinia, telia on Sesleria caerulea: Puccinia sesleriae-caeruleae

10b Aecia in alpine areas on R. pumila:

a uredinia, telia mainly on Calamagrostis varia: Puccinia alpinae-coronata

b uredinia, telia mainly on Sesleria caerulea: Puccinia sesleriae-caeruleae

11a Leaf blades of inconspicuously clustered terminal leaves rolled or conspicuously converging upwards => 13

11b The variously arched or deflected terminal leaves are clustered, nest-like => 12

12a Shoot tips stunted, Leaves loosely arched, ± slightly discoloured. Aphid 1.5 mm long, marbled dark-green. Siphunculi black, twice as long as the oblong cauda. Frangula alnus; Rhamnus alaternus, alpina, lycioides incl. subsp. oleoides: Aphis frangulae

12b eaves rolled backwards, making loose tufts. Aphid 1.5 mm long, greenish-grey. Siphunculi dark, at least at base and tip, twice as long as the short conical cauda. Antennae half the body length. Body laterally with conspicuous small tubercles. R. alpina, cathartica, saxatilis subsp. tinctoria: Aphis mammulata

13a Margins of leaves are loosely rolled downwards, ± bulging => 14

13b Leaves along the midrib and partially also the side veins folded upwards and margins ± strongly rolled. Underside of main venation conspicuously protruding. R. cathartica: Aphis commensalis

14a Mainly on R. cathartica and close relatives, on leaves, margin of which is loosely rolled backwards. Aphid pale green. R. alaternus, alnifolia, cathartica, davurica, imeritina, ludovici-salvatoris, lycioides: Aphis nasturtii

14b Mainly on Frangula alnus in slightly rolled leaves. Aphid marbled dark green. Frangula alnus; Rhamnus alaternus, cathartica, lycioides incl. subsp. oleoides: Aphis frangulae

15a Malformations on leaves => 16

15b Buds swollen. Frangula alnus: Unidentified gall midge

16a Leaf blade abnormally pubescent or margin sometimes with expanded, hardly swollen or with thick succulent folds or rolls => 21

16b Leaf blade with protrusions or lenticular parenchyma galls => 17

16c Small pit-like depressions on underside of leaf. R. alaternus: Trioza marginepunctata

= Two rare Psylla species also cause pit galls on leaves: Cacopsylla rhamnicola on R. alpina incl. subsp. fallax, cathartica, saxatilis and C. alaterni on R. alaternus.

17a Golden-yellow warts or parenchyma galls => 20

17b Protrusions on upper side => 18

18a Mainly on R. cathartica => 19

18b Mainly on R. alpina; corniculate or pouch-shaped protrusions, up to 5 mm long, pale coloured with exit hole on underside. R. alaternus, alpina, lycioides subsp. oleoides, pumila: Trioza kiefferi

19a Small dome-shaped protrusions. A depression on underside containing a flat froth-covered nymph. Also on R. pallasii: Trioza rhamni

19b Protrusions small, ± pinhead-shaped: Aceria rhamni

= On Rhamnus alpinus and Frangula alnus the gall mite Calepitrimerus rhamni causes small finger galls on the upper surface of leaves

20a Underside of basal leaves with many warts, sometimes joining, multi-cellular, ± golden-yellow, less than 1 mm long. Frangula alnus: Synchytrium aureum

20b Inconspicuous parenchyma galls, up to about 5 mm broad, rotund, pale green, protruding and flattened on both sides, soon narrowed towards margins. Manifest as brown spots after departure of larvae. Each containing a single larva. R. cathartica: Unidentified gall midge

21a Underside of leaf with abnormal pubescence => 22

21b Leaf margin curved upwards over a length of 10–20 mm, more rarely rolled. Strongly succulent-cartilaginously thickened; often with abnormal pubescence. in the peripheral, not thickened parts. Rhamnus cathartica, ? Frangula alnus; Rhamnus alpina, erythroxylon, saxatilis: Trichochermes walkeri

21c ne to two pairs of terminal leaves conspicuously folded, often over their complete length, along the midrib and side veins and from margin to the middle part of leaf, or more rolled inwards and upwards. Containing many grey- to blackish-green aphids. R. cathartica: Aphis commensalis

22a Felt-like grey-green pubescence on underside, often emerging from veins. Hairs simple, thread-like or weakly club-shaped. R. alaternus, cathartica: Aequsomatus annulatus

22b Reddish erinea on underside; hairs multi-cellular, acute or obtuse. Frangula alnus: Unidentified gall mite

22c Vein axil along midrib ± discoloured. Abnormal white pubescence on underside in axils and on vein between axils. Frangula alnus: Unidentified gall mite

23a Flower galls => 24

23b Fruit weakly swollen and disfigured. R. cathartica: Wachtliella krumbholzi

24a Flowers swollen, unopened. Stamens and pistil aborted. Containing several whitish, later on sulphur yellow jumping larvae. Frangula alnus; Rhamnus pallasii: Contarinia rhamni

24b Similar galls with reddish-yellow, non-jumping larvae. Frangula alnus: Dasineura frangulae

= May not be independent gall causer, but inquiline in galls of previous midge.

24c Flower buds swollen, club-shaped, calyx green with ash-coloured pubescence, with reddish longitudinal ridges and distal part. Mature gall 5–6 mm long, 2 mm in diameter, coloured brownish when dried. Containing a single white larva. R. alaternus, ludovici-salvatoris: Asphondylia borzi

1a On above-ground parts => 2

1b Root collar, also root- or shoot parts close to surface with rotund galls, up to 5 mm across, single to multi-chambered, sometimes coalesced into conspicuous, tuberculate complexes of various extent. Each oval tough-walled chamber, about 2.5 mm across, containing a single larva. Potentilla spp.: Xestophanes potentillae

1c Nodular swellings without chambers on roots of Argentina anserina: Meloidogyne hapla

2a Galls conspicuous => 8

2b Extended erinea or very small, sometimes coalescing pustules or warts on all above-ground parts => 3

3a Leaf blades, -stalks and stems with small wart-like galls => 4

3b Erinea especially on the underside of sometimes hardly unfolded leaves, also on petioles, on stems and even on calyx. Hairs acuminate-cylindrical. Potentilla spp.: Phyllocoptes parvulus

4a Content of galls and warts yellow-red or pale coloured => 6

4b Content of galls colourless or warts dull-brown to black => 5

4c Underside of the leaves with a greyish white fungal bloom, consisting of erect, distally several times dichotomously branched conidiophores, each one ending in a conidium that is wider than long. P. chrysantha, supina incl.subsp. paradoxa, thuringiaca; also on Aphanes microcarpa: Peronospora oblatispora

5a Warts usually in groups, with colourless content. P. reptans: Synchytrium globosum

5b Pustules dull-brown to black; sometimes coalesced at curved infestation sites to ± expanded bulges. Argentina anserina; Potentilla reptans: Physoderma vagans

6a Warts clearly delineated; hemispherical to short-cylindrical arched => 7

6b Warts simple. P. argentea, heptaphylla: Synchytrium potentillae

7a Warts glabrous. P. reptans: Synchytrium aureum

7b Many (20–40) epidermis cells develop into strongly arched long, acute, white hairs. Plants conspicuously stunted if strongly infected. P. erecta: Synchytrium pilificum

8a On vegetative plant parts => 11

8b On inflorescences or flowers => 9

9a Galls caused by midge larvae or mites living inside flowers => 10

9b Apical shoots, possibly including inflorescences, disfigured, ± clustered, tuft-like. Potentilla spp.: Philaenus spumarius

10a Flowers unopened, abnormally pubescent. Calyx leaves ± elongated, stalk shortened, resulting in ± hidden flowers. Larvae many, orange-yellow to red. P. argentea, inclinata: Dasineura potentillae

10b Calyx of diseased flowers unchanged. Corolla and stamens etiolated, in P. norvegica ± greened. Receptacle elongated, with many stalked fruit primordia. The oblong, or more rotund bundle of young ovaries, if protruding from the flower s are long haired and bear long, ± curved styles. P. argentea, norvegica: Unidentified gall mite

11a Local, also ± expanded, galls on shoot stems, and on the stems of tillers, sometimes also additionally or exceptionally on petiole and even on midrib => 19

11b Malformations on leaf blades or on several disfigured leaves, mainly at, or close to, the shoot tip => 12

11c Small leaf rosette. P. grandiflora, pusilla, tabernaemontani: Guignonia potentillae

= From western Turkey on P. recta leaf bud galls have been reported which are caused by the gall midge Janetiella potentillogemmae. Several larvae live together; subsequent development of galls on lateral buds prevents the formation of side shoots with new inflorescence

12a Predominantly on single, not clustered leaves => 15

12b Mainly on clustered leaves => 13

13a Malformations caused by aphids or spittlebugs => 14

13b Leaves clustered at shoot tip, strongly pubescent. Larvae reddish. P. incana: Unidentified gall midge

13c Middle part of plant transformed into a rosette directly attached to rhizome. The rosette consists of many, 10–15 mm long, usually pale green, linear to lanceolate leaf-like structures. Between the inner linear leaves, still 5–6 mm long and with pale base, a single larva, spinning a snow white cocoon. P. tabernaemontani: Unidentified gall midge

14a Leaves, and also sometimes disfigured flowers ± clustered at the shoot tips. Leaf blades crumpled, deflected, locally intense green. Potentilla s.lat.:. Philaenus spumarius

14b Branches and flower peduncles curved. Leaves variously disfigured. Argentina anserina; Potentilla erecta, reptans: Aphis tormentillae

15a Leaves curved, curled, folded or swollen, bladder-like => 16

15b Leaf blade with yellowish pustules. Drymocallis rupestris: Unidentified psyllid

16a Leaves rolled, folded or ± crumpled and curved => 17

16b Leaf blades with fleshy swollen spots or buckled and bladder-like to greater extent. Galls ± pale-green, on underside or both sides and soon covered with a dirty-grey layer of club-shaped, 8-spored asci. Infestation occasionally also on leaf midrib, -stalk or stem, which are swollen, and sometimes also elongated and ± bent. Drymocallis rupestris; Potentilla anglica, erecta, recta, x suberecta: Taphrina potentillae

17a Malformations without conspicuous pubescence => 18

17b Leaf blade contracted, curled, with stronger pubescence. P. argentea: Unidentified gall mite

18a Leaf midrib strongly deflected. Leaf blade at infestation site crumpled and sometimes deep-green, clustered. Potentilla s.lat.: Philaenus spumarius

18b Leaf midrib stunted, ± bent. Leaflets, ± rolled inwards, containing aphids. Argentina anserina: Unidentified aphid

18c Leaf blade rolled or folded at margin, curved, no abnormal pubescence. Argentina anserina; Potentilla crantzii: Cecidophyes potentillae

19a Galls closed, causers inside the tissue or in distinct chambers => 23

19b Galls open, causers living on surface or fruiting there => 20

20a Malformations contain fungus spores => 21

20b Petioles, also shoot axis, with cylindrical, ± discoloured yellowish, ± buckled swellings, often associated with bending; occasionally several scales solitary in irregularly rimmed depressions on same organ. P. argentea, erecta, grandiflora, hirta, recta: Planchonia arabidis

21a Leaf veins or -stalks with oblong, facultatively sometimes slightly swollen, yellowish spermogonia and orange-coloured caeoma-like aecia bearing pads. [Caeoma is an aecium in which the spores are formed in chains and not enclosed in a peridium]. Fungus monoecious, morphologically distinguished by its telia. Stalk of telia distinctly contrasting. 2–4 germ pores per cell, often situated in the middle or the side-walls => 22

21b Instead of caeoma-like aecia patches, with stalked, solitary primary uredinia. Stalks of telia indistinctly contrasted. Germ pores not apical. Teliospores 2–7 celled, each cell with a single germ pore. Rotund, developing sometimes reddened, with yellow spores occupying small swellings on leaf upperside. P. anglica, argentea, aurea subsp. chrysocraspeda, erecta, x mixta, recta, reptans: Frommeëlla tormentillae

22a Teliospores mainly 4-celled, rounded at apex, papilla absent. Aecia and uredinia with dense, broad warts. Potentilla s.lat.: Phragmidium fragariae

22b Teliospores 5–6 celled, with weak papilla. Aecia and uredinia with fine, loosely arranged warts. Potentilla s.lat.: Phragmidium potentillae

23a Malformations caused by animal inducers => 24

23b Small pustules or bulges on runners, petioles and also leaves. Strongly infected organs often etiolated or distorted. Argentina anserina; Potentilla reptans: Physoderma vagans

24a The inducers occur in larval chambers => 25

24b Soft, compact, spongy galls on the stems of Argentina anserina: Ditylenchus dipsaci

25a Chambers with tough, ± lignified wall => 26

25b Stems with small, rotund, one-sided swellings. Containing a single gall midge larva. P. erecta: Unidentified gall midge

26a Galls at least partially single, ± globular, ± coalesced into larger complexes => 27

26b Swelling spindle-shaped, about 10–30 mm long and 7–15 mm thick, mainly many-chambered and accordingly irregular tuberculate; especially on terminal parts of shoot axis. Each chamber containing a single larva. P. argentea, grandiflora, heptaphylla, inclinata, supina, wimanniana: Diastrophus mayri

27a Single galls about 2–3 mm long => 28

27b Axis of tiller, and more rarely the petiole, with rotund, one-chambered swellings, up to 6 mm thick; sometimes arranged like string of beads or mainly at first slightly bumpy, many-chambered, united groups up to 35 (80) mm long ± fused. Later on the rind bursts open and the single galls emerge more distinctly. Each chamber containing a single larva. Potentilla spp.: Xestophanes potentillae

28a Shoot axis, petiole and midrib with thin-walled, oblong-oval swellings, up to 3 (4) mm long, one-chambered; galls sometimes arranged in rows or groups Potentilla spp.: Xestophanes potentillae

28b Initially green, then brown, about 2 mm long, rotund swellings. One-chambered, mainly solitary or occasionally arranged in groups of various size; single galls however remain distinct and are hardly coalesced. Often close to ground, ± hidden in vegetation, sometimes solitary on petiole. P. anglica, erecta, grandiflora, heptaphylla, incana, inclinata. tabernaemontani: Xestophanes brevitarsis

1a On plant parts above ground => 2

1b Young roots with many, 1–2 mm swellings, variously coalescing and may eventually cover the root as a thick layer. U. minor: Mimeuria ulmiphila

2a In vegetative plant parts => 3

2b Flower buds containing many whitish, rarely yellow, larvae. U. glabra, laevis, minor: Coniophora autumnalis

3a On leaves => 7

3b On axial parts (twigs, branches, stems) => 4

4a On thicker branches => 6

4b On thinner twigs => 5

5a Bark of young shoot axial parts with blunt conical swellings, up to about 3 mm long, at first succulent, later tough-walled. Containing a yolk-yellow larva. U. glabra, laevis, minor.: Janetiella lemeei

5b Thinner stems, particularly of young hosts, with shallow, rimmed bulges, containing an about 3 mm long pear-shaped scale. Ulmus spp.: Chionaspis salicis

6a Bark of stems or thicker branches with conspicuous nodular swellings, at first closed, which ± tear open later on and change into open, irregularly rimmed cancer wounds. Rare on Ulmus spp.: Neonectria ditissima

= Tumors caused by Agrobacterium tumefaciens have also been observed on elm

= Proliferations on elms, so called “bark roses” are caused by the damage of the bark beetle Pteleobius vittatus, which tunnels in the bark anticipating its resting period. The proliferation develops after the feeding of the beetle has been completed, hence it is regenerating tissue, not a true gall

6a Spindle- or barrel-shaped thickenings on branches. Exceptionally on Ulmus spp.: Viscum album

7a Localised or extensive malformations of the leaf blades => 9

7b Galls on leaf veins or petioles => 8

8a Midrib, often at the base of the leaf blade, with a broadly attached swelling up to 15 mm long and 10 (15) mm wide, protruding on the upperside, distorting the leaf; gall wall thick, felt haired, pale sometimes reddened. Opening on underside but dark green aphids leave through a ± star-shaped cleft hole in top of gall. U. glabra, x hollandica, laevis, minor: Kaltenbachiella pallida

8b Midrib, or first order side veins, swollen; mainly on underside, with blunt conical to cylindrical swellings, up to 3 mm long, succulent and single -chambered. Only slightly protruding on opposite side of leaf. Opens at apical part of gall. Also on petioles and young shoots. Containing a single yolk-yellow larva. U. glabra, laevis, minor: Janetiella lemeei

9a Various, small to expanded, localised malformations of unfolded leaves => 12

9b Margins of leaf blade rolled or curled over substantial areas. Aphid galls => 10

10a Aphids pale green to brownish, powdered with wax => 11

10b Aphids black, without wax. Leaves of young shoots curled and loosely deflected, hardly discoloured. Ulmus spp.: Aphis fabae

11a Leaf blade, often only one half, loosely rolled downwards over its length into a bladder-like swollen, slightly thickened, pale green to yellowish tube; often passing over the midrib, especially the terminal part. Surface undulately rugose; veins protruding at the outside, keel-shaped. U. glabra, minor, scabra, according to many authors absent from U americana, glabra, minor, pumila, thomasii: Eriosoma ulmi

11b Open, green to yellow curled-leaf galls containing non-waxy aphids. U. americana, glabra, minor: Eriosoma grossulariae

11c Similar leaf rolls on the lower leaves of young shoots. The developing brood migrates partially to the younger leaves of the same, or neighbouring, shoots, inducing extensive curls and downward rolls but no discolouration. Galled leaves on the ± stunted short shoots clustered later on, nest-like. U. glabra, minor, pumila: Eriosoma patchiae

11d Rolls by inward curling of both edges of leaves, which become blistered, yellow or pale green, or sometimes bright red on younger trees and often considerably distorted. U. minor: Eriosoma anncharlotteae

12a Malformations of various shape, flat or only a few mm high => 15

12b Galls bag- or pouch-shaped, hollow, always higher than 5 mm. Aphid galls => 13

13a Galls pouch- or bag-shaped, about 7–15 mm high => 14

13b Bladder-shaped, 30-80 mm long, irregular enlargements on upperside, usually mostly closed on underside usually developing from a complete leaf. Surface uneven to rugose, densely short-haired, pale green or reddish. Rupturing with irregular slits when mature, then drying out, persisting after leaf fall. Containing waxy aphids. U. glabra, minor incl. subsp. canescens: Eriosoma lanuginosum

13c Leaf blade blistered and raised upwards between veins, green, becoming pinkish brown; containing waxy aphids. U. glabra, minor: Eriosoma flavum

14a Galls laterally flattened, up to 10 mm high; often in the vein axils at the base of the leaf blade; usually slightly grooved, on top cockscomb-like dentate. Often conspicuously red, more rarely yellowish; solitary or with 2–3, more rarely with several broadly attached to the leaf blade. Opening at maturity with a round exit hole on a flattened side. U. laevis, exceptionally U. glabra, laevis, minor: Colopha compressa

14b Galls egg-, pear-, or club-shaped, 7–15 mm long, laterally not flattened, distinctly stalked, mainly on upperside, often ± obliquely protruding, on underside with haired, eventually closed entrance. Surface glabrous, pale green, ± tarnished red. Leaf blade close to the gall discoloured and thickened; often many on a ± distorted leaf. Opens at maturity in the lower part of the swelling, with a lateral crack on the upperside of the leaf. “Fig gall”. U. glabra, laevis, minor; rarely on U. americana, davidiana: Tetraneura ulmi

14c Galls rotund, short stalked, more globular, pea- to walnut-size, often strongly reddened, thin-walled and, in contrast to the former species, short-haired. U. glabra, minor, pumila: Tetraneura caerulescens

14d Galls spindle- or pouch-shaped, hairy, 15‒40 mm high, with pointed apex and usually green and rose-red when mature. U. glabra, minor incl. subsp. canescens, procera, pumila: Tetraneura nigriabdominalis

15a Malformations without conspicuous expanded abnormal pubescence => 16

15b Veins on the leaf underside, especially at the branching points, strongly white haired. Erinea flaky, occasionally restricted to the vein axils. Hairs longer than the normal ones. U. glabra, laevis, minor: Unidentified gall mite

16a Malformations arched, more than 3 mm long, bladder-, groove-, or pustule-like => 20

16b Galls pock-like, wart- or nodule-shaped, about 2 (3) mm => 17

17a Swellings protruding only on one side of leaf => 18

17b Galls nodular, rotund, protruding about equally on both sides, semiglobular on the upperside, more or less conical on the underside, up to 1 mm across, ± short-haired; at first yellowish, eventually brownish. Exit on underside, surrounded by a glabrous rim. Often many per leaf blade. U. glabra, x hollandica, laevis, minor: Aceria campestricola

18a Swellings pock- or wart-like, mainly protruding on underside => 19

18b Pimples, up to 2 mm, rotund, constricted at base, ± rough-haired and pale green pouch galls on the upper side of leaf. On the underside with a small, haired exit hole. U. glabra, x hollandica, laevis, minor: Aceria campestricola

18c Additionally in both previous galls: Aceria multistriata and/ or Anthocoptes galeatus

18d Froth-covered nymphs on underside of leaf produce much honeydew. Leaves wither and become disfigured. U. glabra, laevis, minor: Cacopsylla ulmi

19a Basal leaves on the underside with many, multicellular warts, less than 1 mm across, golden-yellow translucent, distinctly margined. U. minor: Synchytrium aureum

19b Higher situated leaves with many irregularly margined, 1.5‒2.5 (3) mm wide, flat, at first pale-green, eventually brown pocks, predominantly recognisable by their discolouration. Swelling only distinct on the underside. U. glabra, x hollandica, laevis, minor: Aceria ulmi

20a Galls caused by midge larvae, residing in groove-like dimples or in the tissue of flat, rotund malformations, up to about 5 mm wide => 21

20b Leaf blades with few to many, diffuse patches, 2–10 mm long and larger, rotund, sometimes coalescing, usually flat but may be swollen slightly bladder-like to distinctly bulge-like, fungus when mature mainly on underside with ± conspicuous tufts of asci. U. glabra, laevis, minor: Taphrina ulmi

21a Larvae inside the tissue => 22

21b Small grooves, swollen on top, less than 5 mm long, on the leaf underside; surrounded by a discoloured area; often several per leaf. Each groove containing a white larva. U. minor: Dasineura ulmicola

22a Rotund, 3–4 (5) mm wide pustules, situated in the leaf parenchyma, slightly bulging on the upperside, darker or yellowish-green to deep yellow coloured, not protruding on the underside. Containing a single white larva. U. glabra, laevis, minor incl. subsp. canescens: Physemocecis ulmi

22b pperside with very weak, at first yellowish, later on brownish bulges; on the underside a narrow exit hole which is surrounded by a ring of raised cells. Gall chamber is situated below the epidermis and containing a single larva. Ulmus spp.: Unidentified gall midge

1a Malformations of parts above ground => 4

1b Galls on roots or on root collar => 2

2a Galls less than 10 mm, mainly on deeply situated roots => 3

2b Compound up to pea- or walnut-, even fist-sized outgrowths on root collar; above ground as well as subterranean. M. falcata, lupulina, rotata, sativa, x varia: Physoderma alfalfae

3a Spindle-shaped or nodular swellings of the root body. Medicago spp.: Meloidogyne hapla

= Root infestations by Heterodera goettingiana or by unassigned species of the schachtii group have sporadically been attributed to Meloidogyne spp.

3b Small, oval or elongate-cylindrical nodules, up to about 5 mm long, terminally broadened and forked; laterally attached to the root. Medicago spp.: Sinorhizobium meliloti

4a On flowers or fruits => 21

4b On vegetative plant parts => 5

5a Locally delimited galls on buds, stems or leaves => 9

5b Malformations of undefined shape on extended parts of shoot => 6

6a On shoot tips => 7

6b Young plants often substantially atrophied; shoots shortened; strongly swollen, spongy; inserted leaves often severely stunted, their midrib also swollen. Galls necrotic. Medicago spp., especially M. sativa: Ditylenchus dipsaci

7a Malformations with ± strong abnormal pubescence, conspicuous on many hosts, ± colourful, caused by gall mites => 8

7b Systemically infected young plants severely stunted, infected shoots often irregularly bent, also slightly thickened; diseased young leaves ± arched, slightly thickened and pale green; soon covered by a grey-violet, dense mould of conidiophores on undersides. M. falcata, intertexta subsp. ciliaris, littoralis, polymorpha, sativa, truncatula, x varia: Peronospora aestivalis

8a Leaflets folded, ± twisted, also thickened, often discoloured violet, on many hosts with ± abnormal pubescence. Often extensive malformation of plant parts. M. carstiensis, falcata, littoralis, lupulina, minima, sativa: Aceria plicator

8b Shoots terminally stunted, bearing clustered, short stalked, reduced, upwardly arched, undulate, strongly white pubescent leaves. M. lupulina: Unidentified gall mite

9a On lateral-, and occasionally also on terminal buds => 19

9b On stems or leaves => 10

10a On leaf midrib or leaf blade => 12

10b On stems => 11

11a Axis with spindle-shaped, thin-walled, one-chambered swelling. Containing a curved beetle larva. Medicago spp.: Catapion seniculus

11b In similar stem galls on M. falcata, lupulina, sativa also develops: Holotrichapion pullum subsp. aestimatum

11c Globular one-chambered pea-size gall on stem. M. minima: Catapion burdigalense

= Larvae of the snout beetle Protapion filirostre may tunnel in ungalled stems of Medicago species.

11d Stem with smaller spindle-shaped, bent or expanded bulging, usually curved swelling, with rimmed depressions containing a single froth-covered nymph. M. falcata, lupulina: Planchonia arabidis

12a Galls larger than 1 mm => 13

12b Galls hardly 1 mm long, wart-shaped, composite; the content of the strongly enlarged nutritive cell translucent. Warts often many on the underside of basal leaves, on petioles, also on stems, sometimes coalescing, crust- or ridge-like. M. lupulina: Synchytrium aureum

13a Galls with leaf blade parts involved => 15

13b Galls mainly of petiole or main venation => 14

14a Midrib of a leaflet with one or more short, oblong-oval or spindle-shaped swellings, each with a larval chamber. M. sativa: Tychius meliloti

14b Up to 5 mm long, ± oval, yellow-margined, occasionally coalescing, weak bulges on sometimes slightly bent petioles and leaf veins, soon covered by ± dusting of cinnamon- to dark brown sori. M. cyparissias, seguieriana, esula subsp. tommasiniana: Uromyces striatus

15a Leaf blade without conspicuous involvement of midrib folded upwards on both sides, caused by gall midges => 16

15b Nodular to spindle-shaped swelling, extending from midrib into the connate leaf blade halves, with central larval chamber. Containing a single larva. M. falcata, sativa. Tychius crassirostris

16a Gall wall fleshly thickened => 18

16b Gall wall only slightly thickened => 17

17a Gall tightly folded, surface glabrous, discoloured yellowish to reddish. Gall chamber narrow slit-shaped. Larva white- to pale yellow. M. lupulina, minima, sativa, truncatula: Jaapiella jaapiana

17b Galls similar to previous ones, leaflets slightly enlarged, often undulate. Larvae red. M. doliata, falcata, lupulina, sativa, incl. subsp. varia: Jaapiella medicaginis

= In similar galls on M. falcata, prostrata in SE-Eu the yellow larvae of the gall midge Wachtliella dalmatica occur

= On M. sativa red larvae of the gall midge Anabremia medicaginis are inquilinous in leaf fold galls

= From northern Italy the gall midge Diplosiola bursaria has been described on Medicago sativa. Its yellow-orange larvae cause folded leaflets.

18a The galled leaflets are enlarged, forming a pod-like, ± sickle-shaped gall containing orange-coloured larvae. M. falcata, ? lupulina: Dasineura sp.

18b Leaf blade shortened, broader at base, veins on underside strongly thickened. M. prostrata: Wachtliella sp.

19a Galls mainly on M. lupulina => 20

19b Buds swollen, onion-like; gall usually on lateral buds, soft, rotund or oblong, glabrous, ± yellowish, also reddish. Stipules strongly enlarged. Opening at top at maturity, containing several orange-red larvae. M. falcata, littoralis, minima, prostrata, sativa, truncatula, x varia: Dasineura medicaginis

20a Similar, tough-walled galls ± pubescent, often situated terminally, opening by a slit at maturity. Larva maize-yellow. M. falcata, lupulina, minima, orbicularis, polymorpha, sativa subsp. varia: Dasineura lupulinae

20b Up to 5 mm long and 4 mm broad, rotund or ± egg-shaped, closed galls, often overtopped by an atrophied stalked mid leaflet. Sometimes ± enveloped by the swollen stipules. Inner wall with mycelium. Containing a single larva. M. lupulina, minima: Asphondylia lupulinae

21a On fruits => 24

21b On flowers => 22

22a On single flowers => 23

22b Usually all flowers of a raceme are variously greened or leafy, depending on their response ability. M. carstiensis, falcata, littoralis, lupulina, minima, sativa: Aceria plicator

23a Flower buds more or less swollen, onion-like, up to 8 mm long; calyx yellowish. Corolla unopened, its parts ± coalesced, terminal part often beak-shaped. Larvae at first white, later on lemon yellow; gregarious; jumping. M. arabica, falcata, sativa incl. subsp. varia: Contarinia medicaginis

23b Buds soon stunted, ± curved. Occasionally slightly swollen; containing a compact, narrow- and brown-headed, dark cream yellow, strongly bent beetle larva. M. arborea, falcata, lupulina, sativa, x varia: Holotrichapion pisi

24a Pod distinctly shortened, swollen (especially the mid part), often slightly curved at the top. Wall succulent, inside with fungus. M. falcata, sativa, saxatilis: Asphondylia miki

24b Pod conspicuously shortened, transformed into an egg-shaped pouch, often partially enveloped by withered corolla; wall slightly succulent, thickened, inside without fungus. Containing a dirty cream coloured beetle larva with a small brown head. M. falcata, sativa incl. subsp. varia: Tychius medicaginis

1a On parts above ground => 3

1b On roots or rhizomes => 2

2a Reddish, spongy bud gall on rhizome, up to 4 mm long. Contains an orange-yellow larva. C. rotundifolia: Unidentified gall midge

b Main- and side roots with many small swellings, similar to bacterium nodules of Leguminosae. C. rapunculoides: Spongospora campanulae

3a On inflorescences, flowers or fruits => 27

3b On vegetative organs => 4

4a Malformations caused by ± early fruiting fungi at surface => 25

4b Malformations without externally developing fungal fruiting bodies => 5

5a Malformations caused by animal parasites => 6

5b Hardly 1 mm long, hemispherical, ± golden-yellow translucent wart-shaped galls, usually many on underside of rosette leaves, also on stalks as well as on basal stem parts; sometimes ± coalescing. C. herminii, patula, rotundifolia, scheuchzeri: Synchytrium aureum

6a Malformations terminally on main- and side shoots, on buds or on leaves, sometimes including stem parts => 7

6b Axial parts of stem, often the lower parts with ± expanded spindle-shaped swelling with single or several rimmed depressions containing froth-covered nymphs of causers. Campanula spp.: Planchonia arabidis

7a Malformations mainly on leaves, sometimes encroaching onto stems => 14

7b Malformations on shoot tips or on buds => 8

8a Galls loose, spindle-shaped, consisting of ± unfolded leaves, also tuft-like => 11

8b Galls closed, compact, ± onion-like, usually fleshy => 9

9a Rotund or egg-shaped galls, up to 5 mm long, on shoot tips or lateral buds; on larger organs sometimes ± joined into larger complexes => 10

9b Similar, often more slender gall, up to 8 mm long. Also flower primordia severely stunted and disfigured, sometimes overtopped by calyx lobes. Containing several red larvae. C. rapunculus: Dasineura rapunculi

10a Onion-like galls in axillary buds; often overtopped by short rudiments of leaf blades; on shoot tip often united into irregularly composed groups, up to 12 mm broad. Containing one or more brick-red larvae. C. cochleariifolia, persicifolia, rotundifolia, scheuchzeri, trachelium: Geocrypta campanulae

10b Similar, more egg-shaped gall. Contains single yellow-red larva. C. rotundifolia, scheuchzeri: Unidentified gall midge

11a Malformations tuft-like or elongate spindle-shaped => 12

11b Shoot tip stunted; leaves densely clustered, broadened at base and discoloured, terminally spreading; contains several white larvae in axils. C. trachelium: Unidentified gall midge

12a Tufts ± spindle-shaped => 13

12b Tuft terminally on shoot, up to 15 mm long, egg-shaped or globular, containing yellow larvae. C. glomerata: Dasineura campanularum

13a Tufts oblong spindle-shaped, with abnormal pubescence. Leaves rolled inwards and upwards or folded, thickened, abnormally pubescent. Containing a single orange larva. C. barbata, rapunculoides, thyrsoides: Unidentified gall midge

13b Similar gall, not additionally haired. Leaves rolled, slightly thickened and discoloured. Larva whitish, translucent. C. bononiensis, rapunculoides: Dasineura acuminata

14a Leaf blade rolled inwards, curled or swollen locally => 15

14b Leaves disfigured, almost felt-like pubescent. Stem shortened. C. cochlerariifolia, rotundifolia: cf. Aceria campanulae

15a Rolling or curls of leaf blade => 17

15b Leaf blade with ± expanded swelling => 16

16a Crater-shaped, greenish, wrinkled rimmed proliferation on upper side, close to midrib or a side vein; venation disfigured and thickened. C. bononiensis: Inducer unknown

16b Midrib and shortened stalk of several variously distorted rosette leaves swollen, spongy. Tissue brittle, pale green. Galls variously encroaching into the ± stunted leaf blade. C. barbata, carpatica, persicifolia: Ditylenchus dipsaci

17a Leaf blade with margin loosely rolled inwards and ± protruding, curls, caused by aphids or spittlebugs => 22

17b Narrow marginal roll, caused by gall mites or gall midges => 18

18a Margin rolled upwards, with cartilaginous or fleshy thickening, ± discoloured. Midge galls => 21

18b Narrow roll upwards, not discoloured. Mite galls => 19

19a On species with small leaves => 20

19b On C. latifolia, trachelium: Unidentified gall mite

20a Leaf roll tubular, narrow, sometimes remarkably thickened, not conspicuously felt-like pubescent. C. cochleariifolia, rotundifolia: Aceria campanulae

20b Similar roll with abnormal, ± felt-like pubescence. C. cochleariifolia, scheuchzeri, rotundifolia: Unidentified gall mite

21a Roll usually discoloured violet; especially on upper leaves of sterile shoots, also on leaves inserted on roots. Leaf blades sometimes bulging. Usually containing only a single red larva. C. cochleariifolia, latifolia, ? rotundifolia, scheuchzeri: Dasineura thomasi

21b Leaf blade often with cartilaginous, ± wrinkled, usually discoloured upwards roll on both sides. C. bononiensis, rapunculoides: Dasineura acuminata

22a Leaf blade rolled inwards, caused by aphids => 23

22b Leaves loosely deflected, roll- or spoon-like; curled and deep green close to infestation. Contains froth-covered nymph. Sometimes several similarly curved leaves are loosely converging, nest-like, on locally ± stunted and distorted stem. Campanula spp.: Philaenus spumarius

23a Leaves rolled downwards or bent and curled => 24

23b Leaves rolled upwards; stem with shortened, twisted internodes. C. rotundifolia: Unidentified aphid

24a Leaves rolled downwards. Aphid dark red-brown, with rows of black dots, making dark red spots if crushed. Mainly on C. rapunculoides, also on C. cervaria, glomerata, patula, sibirica, trachelium: Uroleucon rapunculoides

24b Leaves deflected, ± curled. Aphids black. C. rapunculoides, trachelium: Aphis fabae

25a Leaves thickened at infestation site, yellowish-green, with whitish-grey down of branched conidiophores on underside. Often the entire plant stunted; leaves in rosettes, non-flowering. C. rapunculoides: Peronospora sp.

25b Upper side of the leaves with pale, slightly embossed patches; on the corresponding underside is a greyish white fungal bloom, consisting of erect, distally strongly branched conidiophores. C. rapunculoides, rapunculus: Peronospora erinicola

25c Sori rust-brown, usually on leaf underside; causing facultatively minor swellings and distortions on venation, on petioles and young stem parts. Telia with 2-celled teliospores, provided with minute warts. Uredinia absent. Usually rare, biologically specialised, also morphologically distinct rusts of the species complex: Puccinia campanulae s. lat.

a On C. cochleariifolia: Puccinia rytzii

b On C. rapunculus: Puccinia campanulae

c On C. rotundifolia: Puccinia campanulae-rotundifoliae

d On C. scheuchzeri: Puccinia campanulae-scheuchzeri

e On C. uniflora: Puccinia novaezemblae; distinguished by glabrous spore walls

f Rust fungi reported from C. glomerata, rapunculoides, trachelium, etc., are assigned to above-mentioned species complex

26a On flowers and inflorescences => 28

26b Ovaries or fruit, including receptacle, succulent, swollen, sometimes distorted; pistil and stigmas thickened, greened; the remaining flower parts necrotic. Contains a single or several larvae. Campanula spp.: Miarus campanulae

27a Flowers or inflorescence greened or leafy => 31

27b Malformation of inflorescence primordia or of flower buds, flowers lacking conspicuous greening => 28

28a Flowers, flower buds unopened and thickened => 29

28b Primordia of inflorescences severely stunted, ± reddened. Flower primordia clustered; especially ovaries disfigured and overtopped by the distorted calyx lobes. Containing several red larvae. C. rapunculus: Dasineura rapunculi

29a Flower buds inflated => 30

29b Flower buds transformed into a succulent, onion-like gall. Contains a single or several brick-red larvae. C. cochleariifolia, persicifolia, rotundifolia, scheuchzeri, trachelium: cf. Geocrypta campanulae

30a The unopened flowers are strongly enlarged at base. Calyx ± stunted; stamens thickened. Larvae white, jumping. C. barbata, cochleariifolia, rapunculoides, rhomboidalis, rotundifolia, scheuchzeri, trachelium: Contarinia campanulae

30b Similar malformations on C. cochleariifolia, rotundifolia, scheuchzeri containing white, non-jumping larvae: Dasineura campanulae

= The curculionid Miarus graminis causes galled flowers of C. glomerata, rotundifolia, trachelium.

31a Flowers greened. C. rotundifolia: Aceria chloranthes

31b Many flowers completely greened over large parts; stunted inflorescence excessively branched and, especially on side branches, the small leaves densely clustered, rolled and curled, often with proliferations on upper side. Host often pubescent with excessive development of hairs. Campanula spp.: Aculus schmardae

1a On above-ground parts => 3

1b On roots => 2

2a Roots close to the surface with an expanded weak swelling, centrally with a wide canal, protruding into the stem and containing a caterpillar. Jacobaea erucifolia, J. vulgaris: Epiblema scutulana

2b Root with small, nodule- or spindle-shaped, cylindrical galls, up to 6 mm long S. vulgaris: Meloidogyne hapla

3a On capitula => 23

3b On vegetative organs => 4

4a Extensive malformations of plant parts; or galls on shoot tips, buds or leaves => 8

4b Galls on stems => 5

4c Stem and leaves greatly swollen and distorted by vivid orange aecia; long, dark brown to black telia may rarely be found at the same time; frequent. Jacobaea vulgaris, Pallenis maritima, Pericallis hybrida, Senecio spp.: Puccinia lagenophorae

4d Stem and leaves slightly swollen and distorted; with powdery orange uredinia and waxy reddish telia; rarely recorded. Senecio s.lat.: Coleosporium senecionis

5a Swelling elongate, situated at different positions. A caterpillar with distinct head capsule lives in a canal in the pith, extending beyond the swelling. Stem close to the gall considerably stunted or completely degenerating, overgrown later on by lower lateral shoots => 7

5b Galls plump, inhabited by larvae lacking a distinct head capsule => 6

6a Stem with padding, often developed on one side, distinctly curved swelling. Galls predominantly in upper stem part, sometimes with several, ± amalgamating. Several yellowish-white jumping larvae. Jacobaea aquatica, erratica, erucifolia, paludosa, vulgaris; Senecio leucanthemifolius subsp. vernalis, sylvaticus, viscosus, vulgaris: Contarinia jacobaeae

= White, non-jumpin, larvae of the gall midge Jaapiella crinita develop as inquilines in galls of Contarinia jacobaeae

6b Stem swollen immediately under the inflorescence. One yellow larva. Jacobaea vulgaris, Senecio sylvaticus: Unidentified dipteran

6c Several rotund galls, up to 10 mm long variously shaped and situated terminally on main- and lateral shoots; also in the inflorescences as well as in buds, petioles and capitula; often extending into neighbouring organs. Centrally one or several large larval chambers with pale yellow to flesh-coloured larvae. Jacobaea vulgaris; Senecio nemorensis, ovatus incl. subsp. stabianus, sarracenicus, sylvaticus: Contarinia aequalis

7a Stem over the galled part ± irregularly thickened, with spindle- to almost nodule-shaped bulges. Galls up to 30 mm long, predominantly on apical sites, with an ejection hole for frass, sometimes bursting. Leaves degenerating. One ivory- to dirty olive-green, black-headed caterpillar. Jacobaea aquatica; Senecio nemorensis, ovatus incl. subsp. stabianus, sarracenicus, sylvaticus: Platyptilia nemoralis

7b Stem in upper third, sometimes immediately below the inflorescence, over a length of 25–35 mm, spindle-shaped to cylindrically swollen. One reddish-yellow caterpillar, the underside paler, with pale brown head capsule. Jacobaea erucifolia, vulgaris; ? Senecio sylvaticus.: Cochylis atricapitana

7c Similar stem gall, in Jacobaea aquatica, vulgaris; Senecio nemorensis, sarracenicus: Platyptilia isodactylus

8a Wart- bulge- or cup-shaped galls on leaves, induced by fungi or psyllids => 16

8b Malformations of large plant parts or galls on shoot tips or lateral buds => 9

9a Malformations on buds or on shoot tips => 15

9b Extensive malformation of the complete plant or malformation of several leaves on the shoot tips => 10

10a Malformations by aphids or cercopids => 11

10b Early infected stems markedly stunted; basally over large extension spongy, swollen, pale green, with rugose, partially undulating surface. Later infestation results in locally expanded one- or often all-sided stem swellings, in conjunction with twisting and curving. Involved organs severely stunted; sometimes also irregularly thickened at the base. Senecio vulgaris, viscosus: Ditylenchus dipsaci

11a Malformations of various kind, usually not specific for the inducer; aphids => 12

11b Large areas on the intensively green site of infestation, strongly bent at leaf apex and ± deflected at margin, curled. Infestation of young stem parts results in stunting and bending of the internodes with ± clustering of disfigured leaves. Senecio s.lat.: Philaenus spumarius

12a Aphids dark green to black => 14

12b Aphids brighter => 13

13a Leaves ± stunted, margins loosely deflected or rolled, curled. Often many per plant, resulting sometimes in conspicuous malformations. Aphid 1.1–2 mm long, bright- to yellow-green. Senecio s.lat.: Brachycaudus helichrysi

13b Leaf blades curled, margins deflected; similar malformations on often many, ± clustered leaves on tips of shoots. Aphid 2–2⅓ mm, greenish to yellowish with large glossy black dorsal patch. Jacobaea aquatica, vulgaris; Senecio spp: Brachycaudus cardui

14a Leaves clustered at tips of shoots and young inflorescence compact, strongly malformed. Leaf blades bent, loosely rolled or curled; capitula ± stunted and disfigured. Aphid 1.5–2 mm long, dirty green to black. Antennae a little longer than half the body length; tibiae black. Jacobaea aquatica, vulgaris; Senecio gallicus, ovatus subsp. stabianus, vulgaris: Aphis jacobaeae

14b Terminal leaves clustered on stunted shoots, deformed, loosely curved downwards and curled. Young plants sometimes completely disfigured. Aphid about 2.5 mm long, dark grey-green to dull black. Antennae half the body length. Legs yellowish annulated. Jacobaea maritima, vulgaris; Senecio spp.: Aphis fabae

15a Shoot tips or lateral buds stunted; Leaves markedly stunted in their development. ± wrinkled and discoloured, heavily whitish pubescent, clustered into an elongated, bud-like shoot. Jacobaea aquatica, vulgaris; Senecio sylvaticus, vulgaris: Aceria leioprocta

15b Terminal- or lateral buds transformed into an irregular, rotund-barrel-shaped, succulent gall. A large chamber inside containing pale-yellow to flesh-coloured larvae. Jacobaea vulgaris; Senecio nemorensis, ovatus incl. subsp. stabianus, sarracenicus, sylvaticus: Contarinia aequalis

16a Wart- or bulge-shaped fungus galls => 17

16b Leaf blade curled, with weak embossment protruding on the upper side. S. nemorensis, ovatus: Trioza senecionis

17a Galls conspicuous; occupied at an early stage by a dusting of sori => 18

17b Galls wart-shaped, coalesced, almost 1 mm long; golden yellow; often many on the underside of basal leaves or on the base of young stems. Senecio vulgaris: Synchytrium aureum

18a Sori ± clearly thickened, bearing aecia => 20

18b Leaf blade often with rotund, bulging pads on the underside or leaf veins, petioles and axial parts with ± spindle-shaped, telia bearing elevations => 19

19a Dark brown, small sori, often occurring on the underside of the leaves, sometimes clustering into larger groups, in that case clearly cecidogenic. Jacobaea alpina, aquatica, subalpina, vulgaris; Senecio spp.: Puccinia expansa

19b Rotund, only slightly- or not thickened, ± yellowish margined sori, 5–10 mm wide, on leaf underside. Senecio ovatus, sarracenicus: Puccinia uralensis

20a Host-alternating fungi, which develop yellowish swellings on Senecio species, bearing their aecia and partially pycnidia => 21

20b Fungus host-specific; on the host only sori with telia develop, besides aecia. Swellings often insignificant. Aecia with whitish peridium; in irregular, loose, smaller groups, rarely extended, on the leaf underside. Jacobaea alpina, aquatica, subalpina, vulgaris; Senecio spp.: Puccinia expansa

21a Aecia on Tephroseris spp. => 22

21b Various rust fungi; recorded from:

a Senecio viscosus, vulgaris: Puccinia opizii

b Jacobaea vulgaris; Senecio viscosus, vulgaris: Puccinia schoeleriana

c Senecio nemorensis, ovatus: Puccinia silvatica

d Jacobaea alpina, aquatica, erucifolia, paludosa, vulgaris; Senecio ovatus, sylvaticus, viscosus, vulgaris: Puccinia senecionis-acutiformis

22a Aecia on the leaf undersides in rotund, often yellow-brown, violet-margined spots. Tephroseris longifolia subspp. brachychaeta, gaudini: Puccinia baldensis

22b Aecia usually on the leaf underside in rotund yellow spots. Tephroseris helenitis, palustris: Puccinia eriophori

= Aecidium senecionis-crispati has been described from Tephroseris crispa.

23a Swollen capitula on otherwise normally developed plants => 24

23b Clustered, shortened, leafy and greened capitula on ± atrophied plants. Jacobaea aquatica, J. erucifolia, J. vulgaris, Senecio sylvaticus, vulgaris: Unidentified ? gall mite

= Stunted but not greened flowers of Jacobaea vulgaris are caused by an unidentified thrips

24a Larvae inside the galls => 25

24b Larvae between the achenes. Capitula not opening, markedly swollen, rotund to broad ovoid, the base especially succulent thickened and yellowish to ± reddened there. Several yellowish-white, jumping larvae. Mainly on Jacobaea vulgaris; less frequent on Jacobaea aquatica, erratica, erucifolia, paludosa, vulgaris; Senecio leucanthemifolius subsp. vernalis, sylvaticus, viscosus, vulgaris.: Contarinia jacobaeae

24c Thickened capitula of S. ovatus containing yellowish, non-jumping larvae of Dasineura senecionis

24d Flower head only inconspicuously swollen bearing a cone of froth which covers a fly maggot. Jacobaea aquatica, incana subsp. carniolica, vulgaris; Senecio ovatus; Tephroseris crispa: Botanophila seneciella

25a Capitula usually only slightly swollen. Larvae in the thickened receptacle => 26

25b Major part of the flower head deformed to form a succulent gall. All organs more or less incorporated in the gall formation, which may extend to the stalk. Inside a large cavity containing pale yellow to succulent-red larvae. Jacobaea vulgaris; Senecio nemorensis, ovatus incl. subsp. stabianus, sarracenicus, sylvaticus: Contarinia aequalis

26a Larvae lacking distinct head capsule and legs => 27

26b Larvae with head capsule and thoracic legs in the slightly enlarged receptacle. S. viscosus: Unidentified lepidopteran

27a Capitula at base often heavily swollen on all sides and discoloured yellow-green, not opening, usually large cone-shaped. Fruits usually withered. Containing a single larva. Senecio s.lat.: Sphenella marginata

27b Receptacle externally only weakly swollen, often on one side, and hardened; later bulging upwards locally. Capitula not opening, mostly cylindrical to narrow cone-shaped. Containing a single larva. Senecio s.lat.: Trupanea stellata

1a On flowers => 23

1b On vegetative plant parts => 2

2a On buds, leaves and thinner twigs => 4

2b In root, trunk or on thicker branches => 3

3a Irregular lumpy swelling on root, 10 mm across or much larger; soft at first, later woody; contains red, purple or brown woolly aphids covered with copious white wax; gall persists long after aphids have left; rare. Crataegus spp.: Eriosoma lanigerum

3b Branches or stems often with conspicuous, club- or barrel-shaped swellings. Crataegus spp.: Viscum album

4a Malformations of various shape, soon occupied by fructifications of fungi => 20

4b Malformations caused by animals => 5

5a Aphid galls => 15

5b Other causers => 6

6a On younger stems, shoot tips or leaves => 7

6b Buds slightly swollen, not opening, occasionally abnormally pubescent. C. laevigata, monogyna: Eriophyes calycobius

6c Vegetative bud unopened, transformed into a rotund mass of small, strongly folded leaves, about 5 mm wide, the external ones making a sort of hood enveloping a shell of aggregated dying leaves. Crataegus spp.: Anthonomus bituberculatus

7a Malformations on single, or several terminal leaves, loosely arranged => 9

7b Galls on thin stems or on shoot tips => 8

8a Leaves on distinctly stunted, slightly thickened shoot tip often in many densely tuft-like clusters. Leaf blades sessile, ± stunted, rugose, occupied by many bolt-shaped or globular green or reddish proliferations. Between the inner, very small leaves are many white, later orange larvae. C. azarolus, coccinea, laevigata, monogyna, rhipidophylla: Dasineura crataegi

= Associated are the yellowish larvae of the inquiline gall midge Prolauthia circumdata.

8b Shoot axis with brown-green swelling, sometimes extending onto the petiole, with easily loosening epidermis. C. laevigata, monogyna: Unidentified gall midge

= The “Hawthorn twig gall midge” Resseliella crataegi, with larvae living gregariously under bark, has not been observed to cause galls.

8c Bark of younger twigs usually with several, ± distinctly rimmed depressions, which contain a rotund, whitish- to brownish-grey scale insect, the inducer. C. rhipidophylla: Epidiaspis leperii

9a Leaves curled or with many small swellings or pocks => 12

9b Leaf margin rolled or leaf blade abnormally pubescent => 10

10a Rolls of leaf margins => 11

10b Underside of leaf with white or violet-red erinea of slightly club-shaped hairs. C. coccinoides, laevigata, macrocarpa, monogyna, nigra, rhipidophylla, sanguinea: Phyllocoptes goniothorax

10c Upper side of leaf slightly protruding at junction of midrib and side vein; corresponding area on underside weakly pubescent. Crataegus spp.: Eriophyes albaespinae

10d Underside of leaf with a longitudinal groove, abnormal pubescence absent. C. laevigata, rhipidophylla: Aculops crataegumplicans

11a Leaf margin tightly rolled downwards, with short club-shaped, at first white, then brownish hairs sometimes extending as erinea into the leaf blade or developing there as isolated patches. C. coccinoides, laevigata, macrocarpa, monogyna, nigra, rhipidophylla, sanguinea: Phyllocoptes goniothorax

11b Leaf roll, containing several red larvae. C. monogyna, laevigata: Unidentified gall midge

12a Leaf blade with many pocks or small swellings => 13

12b Several leaves of suckers on curved stems bent together into a loose aggregation. Leaf blades ± crumpled. Containing a froth-covered nymph. Crataegus spp.: Philaenus spumarius

13a Leaf blade with one-sided archings => 14

13b Leaf blade with many pocks protruding on both sides, often pale green; with narrow opening on underside, occasionally also on upperside. C. laevigata, monogyna: Eriophyes crataegi

14a Leaf blade with many small bulging swellings, yellowish or often carmine-red. Froth-covered nymphs in grooves on underside. C. laevigata, monogyna, rhipidophylla: Cacopsylla melanoneura

14b Leaf blade browned by vagrant gall mites. C. macrocarpa, monogyna, rhipidophylla: Calepitrimerus armatus

14c In similar malformations on hawthorns during the same period also lives Cacopsylla peregrina

14d Leaf blade with small depressions on the underside, and corresponding tiny bulges, often coloured red, on the upper side. In each cavity is one flat froth-covered nymph. C. laevigata, monogyna: Cacopsylla affinis

= The psyllid Cacopsylla crataegi is only weakly cecidogenic, and often reported only as inquiline, or successorium (secondary inhabitant) in aphid galls.

14e Leaf blades usually bent downwards along the venation. Malformations without abnormal pubescence. C. laevigata, rhipidophylla: Aculops crataegumplicans

15a Leaves variously curled, leaf blades not discoloured or sometimes marbled yellow. Malformation usually with many leaves, loosely arranged on shoots or ± clustered on shoot tips => 17

15b Leaves swollen, bladder-like, and conspicuously discoloured yellowish or reddish. Galls caused by several Dysaphis species, all host alternating and difficult to separate => 16

16a Leaf blade usually keel-shaped, curved downwards; segments between the veins especially close to the midrib strongly inflated, bladder-like, discoloured yellowish, not red. Galls mainly on several leaves distributed over the plants. C. laevigata, monogyna: Dysaphis ranunculi

16b Galls usually strongly reddened, otherwise not different from previous species. Often on several neighbouring leaves occurring already during unfolding of leaves. Larvae usually greenish or pink. Aphids mainly distinguished by their different host alternation. Aphids interbreed on Crataegus. Exules on roots, at stem base or sheaths, rarely on leaf blades of basal leaves of various Apiaceae:

a Migrating to Daucus carota, sativus (Anthriscus, Aegopodium): Dysaphis crataegi

b Migrating to Aethusa cynapium: Dysaphis crataegi subsp. aethusae

c Migrating to Angelica: Dysaphis angelicae

d Migrating to Apium graveolens and Petroselinum crispum: Dysaphis apiifolia subsp. petroselini

e Migrating to Heracleum, Conium: Dysaphis lauberti

f Migrating to Laserpitium, Anthriscus: Dysaphis laserpitii

g Migrating to Petroselinum, (Levisticum officinale, Conium): Dysaphis apiifolia subsp. petroselini

h Migrating to Pastinaca sativa: Dysaphis crataegi subsp. kunzei

17a Leaves not conspicuously discoloured => 18

17b Several leaves at shoot tip loosely arched, marbled yellow, soon drying. C. laevigata, monogyna, rhipidophylla, sanguinea: Prociphilus pini

17c Cherry-red to crimson curled-leaf galls in spring. Crataegus laevigata, monogyna: Dysaphis apiifolia

17d Red curled-leaf galls on leaves. C. curvisepala: Dysaphis incognita

17e Pale green or red curled-leaf galls. C. orientalis: Dysaphis virgata

18a Aphids green => 19

18b Aphids black; rolling and curling of young leaves. Crataegus spp.: Aphis fabae

19a Leaves on the unshortened shoots normally distributed or sometimes loosely clustered at shoot tip. Midrib conspicuously bent, screw-like, leaf blade sometimes undulate, nested, loosely or more compactly bent downwards. Aphid with short, thick green siphunculi. C. coccinea, laevigata, monogyna: Rhopalosiphum oxyacanthae

19b Leaves at stunted ends of shoots bent downwards over tip and margins rolled. Aphid with rather long black siphunculi. Crataegus spp.: Aphis pomi

20a Leaves curled or swollen, bladder-like, also young stems partially ± thickened and curved, occupied by grey-white fungal fructifications => 22

20b Considerable yellowish, also reddened, pad- or bulge-shaped swellings on leaves, young stems and even fruits. Galls occupied by spermogonia and aecia => 21

21a Peridium cylindrical, 2–3 mm long, lacerated brush-like later on, divided from the tip into many long lobes. Lateral walls of peridium cells with many, irregularly shaped tubercles of different size. Crataegus spp.: Gymnosporangium clavariiforme

21b Aecia similar. Lateral walls of peridium cells with strong transversely and obliquely running tubercles and ridges. Crataegus spp.: Gymnosporangium confusum

22a Leaves with yellowish-green or reddened bladder-like swellings, at maturity appearing white-frosted because of presence of many asci. Sori occasionally slightly arched, usually on one side, and ± curved swellings on young shoots, flower peduncles and even floral parts; sporadically developing almost witches’ broom-like malformations. C. laevigata, monogyna, nigra, sanguinea: Taphrina crataegi

22b During development of infected young shoots, according to response ability, the internodes partially appearing shortened, slightly thickened, partially etiolated, elongated and in case of mainly one-sided infestation ± conspicuously curved and often ± reddened. Diseased organs covered with a loose white mycelium. Crataegus spp.: Podosphaera clandestina

23a Malformations caused by fungi on flower parts or young fruits => 21, 22

23b Malformations caused by animals => 24

24a Outer parts of flower buds, especially basally, slightly swollen, not opening. Between the inner parts occur larvae with inconspicuous head capsules => 25

24b Receptacle and ovaries sometimes facultatively slightly swollen. Flowers remain closed, corolla distinct between healthy flowers because of its premature browning. Inside is a single larva with distinct head capsule. C. laevigata, monogyna: Anthonomus pedicularius

25a Larvae ivory-coloured, jumping. C. laevigata, monogyna: Contarinia anthobia

25b Larvae red, non-jumping. C. crus-galli, laevigata, monogyna: Dasineura oxyacanthae

= Inquiline of Dasineura oxyacanthae, larvae orange-coloured, non-jumping: Dasineura fusca

1a Galls on root collar or on parts above ground => 2

1b Roots with swellings only a few mm long, nodular or spindle-shaped, which bear side roots. Geranium spp.: Meloidogyne hapla

2a Malformations on inflorescences or flowers => 25

2b Malformations on vegetative parts => 3

3a Malformations caused by fungi, developing on surface or fruiting there => 17

3b Malformations caused by animals => 4

4a Gall formation includes single groups of organs or their parts => 5

4b Complete plant disfigured; basal stem parts variously swollen, spongy, from there developing organs ± reduced and disfigured. G. dissectum, molle: Ditylenchus dipsaci

5a Malformations on plant parts above ground => 6

5b Adventitious buds on root collar transformed into cauliflower-like proliferations, up to 20 mm long. G. molle, pusillum: Cause unknown – ? gall mite

5c Repeatedly reported leafy proliferations, have been attributed to Rhodococcus fascians

5d Closed fleshy proliferations, tuberculate at surface. Geranium spp.: Agrobacterium tumefaciens

6a Malformation of several organs on shoot tips or only on leaves => 7

6b Axial parts of shoot, also petioles, with bulging swellings with rimmed depressions containing the causer. Geranium spp.: Planchonia arabidis

7a Leaves with narrow rolls of margin or with strong pubescence => 10

7b Leaves lacking conspicuous pubescence; leaf blades deflected or loosely rolled, ± curled => 8

8a Malformations induced by aphids or spittlebugs => 9

8b Leaf blade ± curled, without particular curving. G. palustre, pratense: Unidentified hemipteran

9a Leaf blade strongly deflected, often ± nest-like, variously curled, dark green close to infestation. Geranium spp.: Philaenus spumarius

9b Several terminal leaf blades of shoots ± wrinkled and disfigured; tips loosely deflected or rolled. Shoot axis shortened if strongly infected, as well as stalks of clustered leaves. Geranium spp.: Acyrthosiphon malvae

10a Malformations distinguished by strong pubescence => 13

10b Narrow roll of leaf margin lacking conspicuous pubescence => 11

11a Malformation of many terminal leaves on shoots => 12

11b Leaflets often in single basal leaves, rarely in stem leaves, sack-shaped, rolled upwards, lighter. Veins thickened, containing several white larvae. G. sylvaticum: Unidentified gall midge

12a Leaf blade more subdivided, partially narrowly rolled inwards at margin. G. robertianum: Unidentified gall mite

12b Leaves on shortened shoot tip accumulated, tuft-like, tips rolled upwards, appearing almost needle-like, ± thickened, often reddened. Geranium spp.: Aceria geranii

13a Leaf blades with conspicuous rolls of margin => 14

13b Leaf blades with mainly yellow- or red discoloured irregular hunchbacked archings, covered with a white-silk-like glossy, abnormal pubescence. Hairs cylindrical, frizzy. Erinea may also encroach onto petioles, shoot axis and even calyx leaves. Geranium spp.: Aceria geranii

= The gall mite Aceria dissecti has been described from G. dissectum causing deformations of petals and young leaves, and shrivelling of leaves

13c Leaf margins hardly rolled inwards, more densely haired on both sides soon ± brownish discoloured. Mites free-living on leaf underside. G. caeruleatum, robertianum, sanguineum, sylvaticum: Epitrimerus geranii

14a Malformation of many clustered terminal leaves => 15

14b Malformations on shoot tips, of which axial parts, as well as petioles, are elongated and thinner. Leaflets rolled inwards and upwards, white erineum on underside. Inflorescences transformed into whitish capitula. Complete plant ± discoloured. G. molle: Unidentified gall mite

15a Leaves additionally subdivided due to infestation => 16

15b Shoot axis shortened, leaves accumulated, tuft-like, their tips rolled inwards and upwards, ± thickened, reddened, on many hosts conspicuously strongly pubescent. Geranium spp.: Aceria geranii

16a Shoot tip stunted, leaves ± finely subdivided, their tips ± rolled inwards, curved, twisted. Flowers ± distorted, accumulated into capitula, abnormally pubescent. G. pyrenaicum: Aceria schlechtendali

16b Similar malformations on G. dissectum, lucidum, molle, palustre, phaeum, sanguineum, sylvaticum: Aceria dolichosoma

17a Malformations bearing aecia and telia of rust fungi => 19

17b Malformations caused by mildew fungi => 18

18a Minor swelling, up to 1.5 mm long, situated mainly below the leaf blade on petiole, covered by at first white, then ± brown mycelium containing many punctiform perithecia. Geranium spp.: Podosphaera fugax

18b Grey-white down of conidiophores on leaf underside. Leaves usually completely diseased; at first developing faster, longer stalked than healthy ones; leaf blades smaller, yellowish-green, the margins usually loosely rolled downwards. Geranium spp.: Peronospora conglomerata

= The mildew Plasmopara wilsonii causes sharply delimited upper surface leaf spots on G. molle, phaeum, initially some mm large, ultimately often filling the entire leaf; pale yellowish at first, in the end violaceous brown

= Other Plasmopara species on G. palustre, pratense, sylvaticum and relatives occurring in similar down, are much more frequent, but are never cecidogenic

19a Malformations bearing spermogonia and aecia => 22

19b Swellings with only telia => 20

20a Teliospores 2-celled => 21

20b Teliospores 1-celled; on leaf underside in small, dark-brown dusty sori. G. phaeum, ? palustre: Uromyces carpathicus

21a Sori remaining covered by epidermis for a long period. Spores with compact stalks. Pads on leaf underside small, on yellowish to reddish discoloured spots, or sori on spindle-shaped variously distorted bulges on stems, petioles or main veins, up to 20 mm long, usually red to crimson margined. G. albiflorum, macrorrhizum, pratense, sylvaticum: Puccinia morthieri

21b Pads soon naked and powdery; spores easily falling, with warty surface. Sori in densely arranged groups on ± distinct, small or elongated, up to even 80 or more mm long, often variously distorted bulges. Geranium spp.: Puccinia geranii-silvatici

21c On similar malformations on G. macrorrhizum develops Puccinia flahaulti

22a Mature aecia often arched and wide open => 23

22b Mature aecia appearing depressed, with narrow ostiole, margin star-shaped, lacerate, soon falling. Sori on leaf underside on large, rotund, slightly swollen, tuberculate, reddened spots. G. sanguineum: Puccinia oerteliana

23a Aecia on conspicuously thickened pads. Fungi monoecious. Peridium cells only loosely connected. Often conspicuous swellings, often associated with strong distortion, yellowish, sometimes ± reddish margined, on main veins encroaching into the leaf blade, or bulges of variable length on petioles and stems. Geranium spp.: Uromyces geranii

23b Aecia on not thickened leaf sites, surrounded by distinctly discoloured areas. Minor swellings may develop facultatively if sori encroach onto main venation. Fungi host alternating => 24

24a Sori mainly on intensively blood-red or crimson discoloured spots, sometimes additionally surrounded by a yellowish-green area. Peridium cup-shaped with rigidly connected wall cells; after opening the margin finely frayed and bent inwards. Geranium spp.: Puccinia polygoni-amphibii

24b Similarly without intensive marginal discolouration spots develop on G. columbinum, dissectum, molle, pusillum, rotundifolium: Puccinia polygoni

25a On flowers or fruits => 27

25b Expanded parts of inflorescence disfigured => 26

26a Malformation by aphids; the distorted and abnormal pubescent flowers are clustered. Geranium spp.: Acyrthosiphon malvae

26b Flower head-like clustering of disfigured, ± abnormally pubescent flower buds or calyx leaves, caused by gall mites => 14

27a Flowers ± swollen, unopened. Geranium spp. Several unidentified gall midges

27b Fruit basally ± strongly swollen. Containing several orange-yellow midge larvae. G. sanguineum, sylvaticum: Dasineura geranii

1a On parts above ground => 3

1b On subterranean parts => 2

2a Roots with 2–5 mm long, cylindrical galls, sporadically bearing side roots. S. atropurpurea, coeli-rosa, gallica, vulgaris: Meloidogyne hapla

2b Subterranean buds swollen, up to 4 mm across. Leaves clustered, tuft-like, succulent, whitish. Containing a single white larva. S. cucubalus, nutans, vulgaris: Dasineura subterranea

3a On inflorescences or flowers => 30

3b On stems, shoot tips, axillary buds or leaves => 4

4a Malformations on leaves, shoot tips, axillary buds or upper stem parts => 8

4b Basal rosettes or basal shoot organs largely disfigured, or leaf blades of rosette leaves with small yellowish warts => 5

5a Malformations caused by animals => 6

5b Leaf blades of rosette leaves with many warts, less than 1 mm long, multicellular, yellowish, occasionally coalescing; also on basal stem parts. Silene flos-cuculi: Synchytrium aureum

6a Malformations of basal leaves or leaf blades => 7

6b Young plants severely stunted. Stems stunted, spongy, swollen, inserted leaves variously disfigured. Silene spp.: Ditylenchus dipsaci

7a Basal leaves stunted. Leaves with their base spindle-shaped, converging; containing a green caterpillar, distinguished by its dark red first segment. It feeds on bast and cortex of young stems, which appear slightly thickened because of callus formation. S. nutans: Caryocolum sp.

7b Leaf blades of basal leaves in longitudinal direction knee-like bent, almost at right-angles, at any point. Breaking point close to midrib succulent, swollen, usually yellow-green, sometimes reddish. S. viscaria: Planchonia arabidis

8a On shoot tips, side shoots, and -buds or on leaves => 14

8b On axial parts of shoot => 9

9a Malformation caused by larvae with a distinct head capsule => 10

9b Swellings spongy; very variable in shape and expansion; with undulate or wrinkled surface. Silene spp.: Ditylenchus dipsaci

10a Malformations caused by a pith-tunneling caterpillar => 11

10b Stem with conspicuous ± spindle-shaped or cylindrical, tough-walled, glabrous swellings; caused by beetle larvae. Galls about 10 mm long and 5 mm thick, spindle-shaped or cylindrical; single or with a few together. Containing a single larva. Silene spp.: Sibinia femoralis

11a Galls very conspicuous on all sides, more than 15 mm long => 12

11b Stem stunted, ± swollen and curved. S. nutans, otites, viscaria: Caryocolum amaurella

12a Up to 30 (40) mm long and 8 (10) mm thick spindle-shaped-cylindrical gall, situated in the shortened internodes. A long tunnel in pith containing a dirty-grey, brown-headed caterpillar => 13

12b Swellings in axial parts of shoot tips. S. hayekiana, saxifraga: Caryocolum saginella

13a On S. dichotoma, gallica, italica, nutans,otitis, parviflora: Caryocolum cauligenella

13b On S. vulgaris: Caryocolum inflativorella

14a Galls on tips or buds of main- or side shoots => 25

14b Malformations mainly on leaves, sometimes encroaching into stem parts => 15

15a Malformations only minor, bearing sori of fungi => 22

15b Malformations caused by animals => 16

16a The causers are external on the galled tissue => 17

16b Spongy, swollen on both sides, ± wrinkled or undulate swelling on petiole or leaf blade; on narrow leaves also proliferating beyond the margin. Sometimes all parts of a rosette or of young plants are disfigured. Containing many eelworms. Silene spp.: Ditylenchus dipsaci

17a Leaves folded upwards over the midrib, ± discoloured. Malformations often on many plant parts. Caused by aphids => 18

17b Shoot axis locally stunted and ± curved. Leaves deflected over their tip, undulately curled; often clustered, nest-like, on the ± stunted stem parts. S. armeria, flos-cuculi, gallica, vulgaris: Philaenus spumarius

= As causer of similar malformations of shoot and leaves Taeniothrips atratus has been sporadically indicated.

18a Aphids pale green or yellowish => 21

18a Aphids red to dark-brown or black => 19

19a Aphids black => 20

19b Aphids red to dark brown. Leaves rolled downwards. S. alba, flos-cuculi: Myzus certus

20a Young leaf blades curled or rolled slightly downwards, caused by glossy black aphid with very short, rounded cauda. Silene spp.: Brachycaudus lychnidis

20b Flat, not discoloured bulges. S. alba, dioica. Wingless aphids with dull black body and tongue-shaped cauda: Aphis fabae

21a Apterae are whitish yellow to pale green, strongly wax-powdered; body length 1.4‒2.2 mm. Antennae half the body length. Siphunculi much shorter than the oblong, black cauda. S. vulgaris and varieties: cf. Brachycolus cucubali

21b Aphid yellowish or pale green, glossy, body length 1.4‒1.8 mm. Antennae about two-thirds of body length. Siphunculi weakly clavate, pale yellowish, only slightly longer than the yellow cauda. S. alpina, atropurpurea, flos-cuculi, nutans, otites, pendula, suecica, viscaria: Volutaphis centaureae

22a Malformations bearing yellowish to yellowish-white sori => 23

22b Minor rotund or oblong dense sori, sometimes bulging on venation, bearing dark-brown, 2-celled teliospores. Silene spp.: Puccinia arenariae

23a Aecia on several Silene species, S. nutans excepted => 24

23b Aecia mainly on S. nutans. Peridium short cylindrical, with white, deflected margin, subdivided into long narrow lobes. Uromyces inaequialtus

24a Malformations and aecia similar to those of preceding fungus. Spots on upperside often reddened. Aecia disc-shaped with strongly lacerate, deflected margin. Fungus lacking uredinia, with repeated development of aecia. S. cucubalis, alpina, densiflora, dichotoma, dioica, elisabethae, maritima, noctiflora, nutans, otites, rupestris, uniflora incl. subsp. thorei, vulgaris incl. subsp. prostrata: Uromyces behenis

= Witches’ broom-like malformations after infestation on S. uniflora may also be caused by this rust fungus.

= On S. otites the aecia of a host-alternating fungus (Aecidium otitis) have been recorded repeatedly with unknown life-cycle

24b Occasionally on cultivated plants of S. coeli-rosa, etiolated shoots with narrowed, paler leaves have been observed bearing on the undersides expanded, scattered yellow sori of Melampsorella caryophyllacearum

24c Aecia arranged in circular groups on hypertrophied sori on various organs, often crowded, more rarely extending over complete leaf; accompanied by spermogonia and often uredinia, less by 2-celled teliospores. Peridium very small, short cylindrical, with lacerate white margin. S. vulgaris, more rarely S. armeria, nutans, pendula, etc.: Puccinia behenis

25a Galls not excessively pubescent => 27

25b Malformations with abnormal whitish pubescence => 26

26a Leaves on shoot densely clustered. Leaf blades rolled and ± curved, almost linear; strongly white pubescent. In case of severe infestation the whole plant is atrophied. S. nutans: Unidentified gall mite

26b Almost bud-like accumulation of severely stunted, disfigured and abnormally haired leaves on shoot tips or in axillary buds. Containing several white larvae. S. alba, densiflora, dichotoma, dioica, latifolia,noctiflora, nutans, otites: Neomikiella lychnidis

26c Similar malformations of shoot tip, lateral buds, inserted unfolding leaves with loose, fleshy thickened marginal upward roll, exceptionally also downwards. Containing several white larvae. S. nutans: Unidentified gall midge

27a Malformations ± bud-like; caused by midge larvae => 29

27b Galls elongated, not of compact bud-like appearance, caused by midge larvae as well as other inducers => 28

28a Apical parts of plant distorted and discoloured. Silene alpina: Volutaphis alpinae

28b Leaves accumulated at the shoot tip over its length loosely upwardly rolled and ± thickened, bearing aphids or thrips. S. vulgaris, nutans: cf. Brachycolus cucubali

28c Several leaves of stunted shoots distorted, variously rolled and curved. S. latifolia, vulgaris: Taeniothrips atratus

28d The upper leaf pair of shoot tip erect, slightly thickened at base; the margins folded together or rolled. Containing several white to pale orange larvae. S. vulgaris: Macrolabis sp.

28e Similar galls containing white, jumping larvae. S. vulgaris: Contarinia cucubali

28f Leaves of shoot tip bushy clustered. S. nutans, vulgaris: Unidentified gall midge

29a Up to 10 mm long, ± onion-like, glabrous galls on the axillary buds or tips of lateral shoots. Containing several white larvae. S. vulgaris: Macrolabis sp.

29b Leaves bud-like accumulated on vegetative shoots, stunted, at base broadened, thickened and ± discoloured. Larvae pink-red. S. acaulis: Jaapiella alpina

29c The youngest one- or two pairs of leaves at the tip offside shoots are narrowly rolled into one another, swollen at base and discoloured. Containing several red larvae. S. viscaria: Jaapiella viscariae

29d Several rolled glabrous leaves form a spindle-shaped bud gall at the vegetative tip, contain many cream-coloured gall midge larvae. S. behen: Macrolabis behen

30a Malformation of flowers and of flower parts caused by fungi => 40

30b Malformations of inflorescences or single flowers caused by animals => 31

30c Fruits swollen. S. alba, dioica, fruticosa: Sibinia pellucens

31a Flowers unopened, swollen. Containing midge larvae => 34

31b Flowers ± stunted, their parts variously greened or leafy => 32

32a Malformations associated with a strong stunting of inflorescence => 33

32b Malformations usually restricted only to the sometimes shortened axial parts of stem. All flower parts leafy inside the hardly changed calyx. Inflorescence axis sometimes ± developing further. S. nutans, otites, rupestris: Aceria silenes

32c Malformations on S. “parviflora”: Eriophyes parviflorae

32d Flowers greened, transformed into small shoots bearing strongly pubescent little leaves. Also the vegetative buds may develop similarly disfigured, ± elongated, dense bunches. S. alba, dioica, latifolia vulgaris: Unidentified ? gall mite

32e Inflorescence stunted, disfigured, flowers clustered. Conspicuous pubescence absent, calyx widened, enclosing greened organs. Unidentified gall mite

33a Complete host stunted, flowers greened. S. dichotoma: Inducer unknown, ? virus

33b Flowers on usually severely stunted plants transformed into a widely protruding rosette of variously disfigured little leaves; stamens hardly disfigured but greened. S. alba: Inducer unknown – ? virus

33c Axial parts of inflorescence ± compact. Flowers ± clustered; calyx swollen. Organs inside variously disfigured and greened. S. vulgaris: cf. Brachycolus cucubali

33d Similar malformations on inflorescence. S. alba, vulgaris, occasionally S. baccifera, borysthenica, coronaria, dioica, italica, latifolia, uniflora, viscaria: Brachycaudus lychnidis

33e On S. dioica. Between strongly inflated calyx and stunted corolla: cf. Brachycaudus lychnidis or B. klugkisti

34a Galls usually with dense abnormal pubescence => 39

34b Galls not, or only slightly more pubescent than the normal organs => 35

35a On Silene species, but not S. alba, dioica, latifolia => 36

35b On S. alba, dioica, latifolia. Flower buds swollen, stunted, mostly unopened, on usually inconspicuously shortened axial parts of inflorescence. Containing several midge larvae, at first white, soon yellow, jumping: Contarinia steini

36a On Silene species, S. italica, vulgaris excepted => 37

36b On S. italica, vulgaris & subsp. glareosa: Calyx conspicuously swollen, largely unopened. Also the other flower parts enlarged and exceptionally ± leafy. Larvae yellowish to pale red: Jaapiella floriperda

36c Also described for similar galls on same hosts. Larvae white: Jaapiella cucubali or J. inflatae

37a On Silene species, but not S. atropurpurea, flos-cuculi, viscaria => 38

37b On S. flos-cuculi, viscaria, similar galls contain many red larvae: Dasineura praticola

37c On S. viscaria, similar galls contain only 4–8 red-yellow larvae: Jaapiella moraviae

38a On Silene species, but not S. nutans => 00

38b On S. nutans. Flowers stunted; ± globular, unopened, hardly swollen. Sometimes on the ± shortened axial parts clustered into rotund, sometimes weak whitish pubescent balls. Containing midge larvae. Unidentified gall midge

38c On S. nutans. Swollen flower buds, abnormally pubescent. Calyx strongly thickened. Larvae yellowish to pale red: Dasineura bergrothiana

39a On S. bupleuroides. Flower buds swollen, pale, unopened. Calyx thickened; corolla greened. Containing several yellow larvae. Unidentified gall midge

39b On S. otites. Flowers transformed into a rotund gall, up to 4 mm. Calyx abnormally pubescent. Corolla greened. Stamens ± normal. Containing red, non-jumping larvae. Dasineura sp.

39c Similar galls on S. parviflora, pseudotites: Unidentified gall midge

= In C-Eu occasionally galls on S. nutans, otites consisting of several, densely clustered, severely stunted and whitish pubescent buds; between the buds live white larvae of a gall midge assigned to Neomikiella lychnidis. Galls on these hosts often simultaneously occurring in vegetative shoot tips or lateral buds

40a Fungus fructifies in the ± distinctly swollen anthers. Spores separated, not arranged in easily decomposing balls; ± violet tinged. Other flower parts not galled => 43

40b Flower buds stunted, unopened, transformed into globular to broad egg-shaped galls. Inner part soon destroyed and displaced by a yellow- to tobacco-brown spore mass, consisting of many easily decomposing balls => 41

40c lowers leafy or partially greened. Organs variously disfigured, transformed into sometimes ± clustered, ± reddish tufts. S. viscaria: Cause unknown

41a On several Silene species, S. otites excepted => 42

41b On. Silene otites. Diseased flowers distorted; often distinctly swollen, for a long period unopened, corolla usually atrophied. Sori rupturing later on and with dusting: Microbotryum majus

42a On Silene alba, alpestris, dioica, nutans, rupestris, vulgaris. Flowers outwardly hardly changed. Infestation caused by this fungus results in an early opening of the flower accompanied by a shortening and swelling of the stamens, and in the female flowers a transformation into similarly disfigured anthers: Microbotryum violaceum

= Microbotryum heliospermae is an anther smut fungus occurring on alpine S. pusilla; M. silenes-saxifragae is an anther smut fungus on S. saxifraga

42b On many other Silene species. Flowers outwardly hardly changed. Spore mass usually pale grey-violet: Microbotryum silenes-inflatae

= The smut fungus Microbotryum silenes-dioicae transforms the content of the anthers of S. dioica into a brown vinaceous mass of spore

= Note: because the fungus leaves the ovary intact, the negative impact on the reproductive capacity of the flower is very limited. The real damage is caused by the gall midge Contarinia steini, see lead 35b.

= Microbotryum silenes-acaulis has been reported on S. acaulis, uniflora

43a On S. alba, dioica, latifolia, mollissima, nutans, repens, thymifolia, uniflora, velutina, vulgaris: Thecaphora melandrii

43b On S. flos-cuculi, viscaria: Thecaphora saponariae

1a On inflorescences, flowers or fruits => 23

1b On vegetative parts => 2

2a On parts above ground => 6

2b On root collar or on roots => 3

3a On roots => 4

3b Root collar with ± rotund, succulent swellings, about 8–10 mm long, containing a single larva. Galls, especially on perennial species, often many per plant and largely coalesced into ± lumpy gall complexes; sometimes also on the basal stem parts or close to surface on main root, especially on cabbage. B. napus, oleracea: Ceutorhynchus assimilis

= The snout beetles Aulacobaris coerulescens and Melanobaris laticollis have erroneously been reported as inducers of root collar-, root- and stem galls. The larvae develop by boring into ungalled roots or above ground stem parts and occasionally arrive in galls already produced by other inducers

4a Nodule-shaped swellings, only a few mm long, on the finer side roots, not noticeably swollen, transiently bearing cysts => 5

4b Main- or side roots often with very conspicuous, often clustered, spindle- or ± finger- to nodule-shaped, thick succulent, massive swellings; inside many cells with dense masses of minute spores. B. oleracea: Plasmodiophora brassicae

= Occasionally conspicuous nodular proliferations occur on main roots, or more frequently on above-ground parts, especially on forms of B. rapa. The tissue is, in contrast to that caused by Plasmodiophora brassicae, uniform coloured and without development of spores. Cause unknown, but some authors attributed these malformations to Agrobacterium tumefaciens

5a Roots with spindle-shaped or rotund, smaller, sometimes about pea- to exceptionally nut-size swellings caused by eelworms living inside. B. napus, oleracea, rapa, incl. subspecies and forms. Meloidogyne hapla

5b Inconspicuous, some side roots bearing root galls. B. napus, oleracea: Meloidogyne artiellia

5c Roots externally not swollen; inside with giant cells. Occasionally stronger development of side roots. Temporarily at surface with about poppy-seed sized, lemon-shaped, at first milk white, then browned cysts. Brassica spp.: Heterodera schachtii

5d On many cabbage species occur also the very similar, but slightly smaller, on average up to 0.6 mm, and more rotund cysts of Heterodera cruciferae

6a Malformations with white sori on surface => 22

6b Malformations caused by animal parasites => 7

7a Terminally on main- and side shoots => 18

7b On stems or leaves => 8

8a On stalks or leaf blades of leaves => 10

8b Stem with short spindle-shaped or elongate expanded swellings => 9

9a Thin stems with all-sided, thicker stems with one-sided, spindle-shaped swellings, 10–15 mm long, glabrous, also green inside. Contains a single larva. B. napus, nigra, oleracea, rapa: Ceutorhynchus chalybaeus

= Aulacobaris coerulescens, A. cuprirostris, A. lepidii, A. chlorizans have been reported as causers of stem galls. The larvae tunnel in the stem and the thicker roots; pupation in the gallery

9b Development of stem, especially of winter oil seed, stunted in spring, swollen over variable length, often ± s-shaped curved, often erupting over large expansion. In the strongly enlarged pith many, up to 7 mm long, yellowish-white apodous larvae with brownish, relatively large head capsule. B. napus, oleracea, rapa: Ceutorhynchus napi

= Occasionally has, especially for Brassica, been recorded Ceutorhynchus pallidactylus. Oviposition is not followed by gall formation. For B. rapa thickened leaf parenchyma has been reported caused by Ceutorhynchus leprieuri

10a Malformations mainly of leaf blades => 12

10b Galls on petioles or main venation => 11

11a Galls 10–15 mm long, compact, spindle-shaped, with glabrous surface, also green inside. B. napus, nigra, oleracea, rapa: Ceutorhynchus chalybaeus

11b Stems of germinating, also older plants or petioles, usually also the basal part of midrib shortened, spongy, swollen, yellowish green; at infestation sites brittle and necrotic, at surface ± undulately-wrinkled, variously on leaf blades, also encroaching on parts of rape. B. napus: Ditylenchus dipsaci

12a Leaf blade ± curled, loosely rolled inwards or folded => 14

12b Leaf blade with very narrow marginal roll or with lenticular galls => 13

13a Galls occurring from autumn to early spring; lenticular, up to 5 mm across, succulent, on both sides flat protruding, also green inside, especially conspicuous on yellowing parts, often many per leaf, often including main veins. Containing a single larva. B. rapa, rarely B. napus, oleracea: Ceutorhynchus leprieuri

13b Leaf blade with narrow marginal roll upwards. B. nigra: Inducer unknown

14a Malformations caused by aphids or spittlebugs => 15

14b Leaf blades to varied extent swollen and stunted, bent upwards along midrib; pale green; several whitish to pale yellow, jumping midge larvae on upper side between folds. B. napus, oleracea, rapa, souliei subsp. amplexicaulis: Contarinia nasturtii

15a Malformations caused by aphids => 16

15b Leaf blades of larger leaves deflected into mainly oblique rolls or distortions; usually curled and deep green close to froth covered froth-covered nymph. Brassica spp.: Philaenus spumarius

16a Aphid green => 17

16b Aphid black. Leaf blade at margin ± deflected, curled, infestation mainly on terminal stem leaves. Brassica spp.: ? Unidentified aphid

= Black aphids of Aphis fabae s.l. do not cause galls on Brassica. However, they may occur as inquilines in galls caused by other inducers

17a Leaf blade with expanded, conspicuously bulge- or bladder-like, pale green, on many species sometimes reddish or violet marbled folds or swellings; large colonies of densely grey-powdered aphids often on underside. B. napus, oleracea, rapa: Brevicoryne brassicae

17b Aphid not mealy powdered. Leaf blades of stem leaves often rolled downwards at margin, ± curled. B. napus, oleracea: Myzus persicae

18a Galls on tips of rosette leaves => 19

18b Tips of flowering main- and side shoots severely stunted; leaves as well as flower buds densely clustered, variously swollen at base. Similar malformations also on axillary, often hardly developed shoots. Between the galled parts are several whitish- to pale yellow, jumping larvae. B. napus, oleracea, rapa, souliei subsp. amplexicaulis: Contarinia nasturtii

19a Inducers live inside malformations => 20

19b Central leaves disfigured. Lower parts of petiole, vegetative point, especially at infected area, strongly swollen and bent sidewards. Between galled parts are several whitish- to pale yellow, jumping larvae. B. napus, oleracea, rapa, souliei subsp. amplexicaulis: Contarinia nasturtii

20a Shoot thickened over variable length, stunted. Leaves ± clustered, the inner ones often severely stunted or dead. Pith often contains several beetle larvae => 21

20b Stem of young plants completely or partially spongy, pale green; infestation similarly encroaching into petioles and leaf veins, mainly on underside. Galls contain many eelworms. B. napus: Ditylenchus dipsaci

21a Shoots, occasionally also leaf base of non-shooting forms, distinctly thickened; pith greatly increased. Vegetative point often largely stunted or necrotic. Several beetle larvae in heavily infected pith. B. napus, oleracea, rapa: Ceutorhynchus napi

21b Similar, usually weaker swellings inhabited by only 1 to 3 larvae. B. oleracea and forms. Ceutorrhynchus rapae

22a Loose down of branched conidiophores in ± expanded sori on the underside of only pale leaves. Rarely on leaf veins or young stems causing occasionally minor swellings, usually containing oospores. B. napus, nigra, oleracea, rapa: Hyaloperonospora brassicae

22b Sori on leaf underside rotund, on stem parts oblong-oval to spindle-shaped, compact, at first closed, glossy, porcelain-like, with mealy dusting after rupturing. Often many per plant; hardly cecidogenic on the leaf blades, on young stems often developing distinct pads. B. juncea, napus, nigra, oleracea, rapa: Albugo candida

22c Leaf with small hard, solid, gregarious pustules caused by fungus, less than 0.5 mm across. Brassica spp.: Synchytrium aureum

23a Malformations on single or many flowers or fruits; stem parts hardly disfigured => 26

23b Inflorescence disfigured => 24

24a Malformations caused by aphids or spittlebugs => 25

24b Racemes greatly shortened terminally; flower buds densely clustered, severely stunted, occasionally swollen at base. Between buds are several whitish- to pale yellow, jumping larvae. B. oleracea, rapa, souliei subsp. amplexicaulis: Contarinia nasturtii

25a Midrib locally swollen and severely stunted, usually bent to one side; flowers clustered, variously disfigured. Leaves distorted and curled. Containing a froth-covered nymph. Brassica spp.: Philaenus spumarius

25b Inflorescence broom-like disfigured and bent, longitudinal growth stunted. Flowers often mostly necrotic; occasionally also several largely disfigured shoots. Stems at first bearing ± densely grey powdered aphids. B. napus, oleracea, rapa: Brevicoryne brassicae

26a Malformations of ovaries or fruits => 29

26b Malformations of flowers => 27

27a Single or several buds of inflorescence swollen, unopened => 28

27b Usually consecutive flowers of large parts of inflorescence, often terminally of raceme variously disfigured; especially the ovaries prematurely elongated and increasing towards the top, swollen like enlarged, slender Capsella siliques; stamens and corolla disfigured, greened and often, like calyx necrotic. B. napus, oleracea and forms. Cause unknown – ? virus disease

28a Gall ± globular; calyx enlarged; corolla shortened; stamens disfigured, their filaments swollen and bent; anthers aborted; ovaries stunted, swollen; style and stigma necrotic. Containing several white, later on pale yellow, jumping larvae. B. oleracea, rapa, souliei subsp. amplexicaulis: Contarinia nasturtii

28b Similar flower galls with several, but non-jumping, larvae which are also white when mature. B. barrelieri, napus, oleracea, rapa: Gephyraulus raphanistri

29a Young or often well-developed shoots ± shortened and slightly swollen over their complete length, or with ± expanded often pale green swellings causing conspicuous curving. Galled siliques sterile or ± early bursting => 30

29b Ovaries, sometimes also calyx leaves and stamens, conspicuously disfigured, enlarged, with white at first closed, soon dusty sori. B. juncea, napus, nigra, oleracea, rapa: Albugo candida

30a Larvae white, only rarely pale yellow later on, non-jumping, usually many per silique. B. napus, oleracea, rapa: Dasineura napi

= Fruit galls, occasionally recorded from literature for Ceutorhynchus assimilis or for larvae of unidentified snout beetle, might also be attributed to this midge

30b Silique swollen, contains a single orange midge larva. B. nigra: Asphondylia stefanii

1a On parts above ground => 4

1b On subterranean buds, shoots or roots => 2

2a On buds or stems => 3

2b Roots with small nodular or slender spindle-shaped swellings, up to 6 mm long. E. peplus, cyparissias, helioscopia: Meloidogyne hapla

3a Underground part of usually severely stunted shoot axis often with already on rhizome with an up to about 10 (12) mm long and 4 (6) mm broad, acorn- to spindle-shaped, rough-walled swelling. The terminally situated shoot is severely stunted and soon shrivelling. Containing in the widened pith a compact, cylindrical maggot with black pharyngeal skeleton; puparium later on dark brown. E. cyparissias, amygdaloides: Pegomya euphorbiae

3b Underground stem with large swelling that incorporates leaf buds; cavity inside with a maggot or puparium. E. cyparissias, esula, amygdaloides: Pegomya argyrocephala

4a Expanded malformations on shoots, soon bearing fruiting bodies of fungi => 15

4b Malformations caused by animals => 5

5a Galls on flowers or inflorescences => 13

5b Malformations on vegetative parts => 6

6a Galls only terminally on main- or side shoots, or on axillary buds => 9

6b Malformations on leaves or on expanded shoot parts => 7

7a On several organs of shoot => 8

7b Margin of leaf blade rolled inwards. E. nicaeensis: Unidentified gall midge

8a All terminal leaves of a shoot, also entire plants ± twisted spirally, loosely rolled upwards and inwards, discoloured yellowish or reddish; terminally sometimes clustered into loose tufts. E. amygdaloides, cyparissias, epithymoides, esula, peplus, palustris: Eriophyes euphorbiae

= The gall mite Phyllocoptes euphorbiae causes malformation of apical shoots of E. cyparissias, salicifolia

= The gall mite Aculops euphorbiae on E. spinosa causes drying of apical plant parts, buds and flowers

= The gall mite Eriophyes septemlineatus causes drying and malformation of terminal growth points and inflorescences on E. dendroides

= On E. glabriflora, amygdaloides, capitulate, serpentini the gall mite Aculops glabriflorae causes shortening and drying of vegetative growths and deformation of the inflorescence, and on E. myrsinites the gall mite Aculops montenegrinus causes similar malformations

8b Malformations caused by thrips on leaves of E. cyparissias, esula subsp. tomassiniana, myrsinites: Anaphothrips euphorbiae

8c Plants often severely stunted, infected stems, and other parts swollen, spongy ± distorted. E. helioscopia: Ditylenchus dipsaci

8d Minor swelling of twigs. E. characias: Thamnurgus characiae

8e Similar gall. E. amygdaloides, characias: Thamnurgus varipes

9a Leaves not connate, terminally clustered into a globular or elongated, ± bud-like tuft => 10

9b Upper 2–7 leaves connate forming a capsule-like gall; up to 15 mm long and 10 mm thick, sometimes rotund, usually oblong, pear- or bottle-shaped. Wall striate and hard. In smaller forms also on axillary buds as well as in inflorescences. Larvae orange-coloured to vivid red. Euphorbia spp.: Dasineura capsulae

10a Many leaves strongly broadened; curved over their complete length, tips converging towards gall, making a rotund, ± compact gall => 12

10b Tuft of leaves more loose and oblong, composed of several to many leaves; these with erect or sometimes ± deflected terminal part => 11

11a Tuft up to 30 mm long and 7 mm thick, consisting of 4–5, almost pod-like converging leaves. Sometimes also the following 2–3, ± spreading leaves similarly curved. Containing a single pale orange-red larva. Euphorbia spp.: Dasineura schulzei

11b Similar loose tuft gall; mainly known from Italy; very rare. E. esula: Spurgia esulae

12a Galls compact and ± globular, up to 10 mm across, yellowish-green, often conspicuously reddened; usually containing many orange-red larvae. Euphorbia spp.: Spurgia euphorbiae

= Similar galls on E. cyparissias may contain inquilinous white midge larvae: Macrolabis lutea

12b Terminal gall consisting of short leaves, thickened, leather-like, enveloping one another at base and making a rosette in their terminal half. Containing several yolk-coloured larvae. E. characias: Janetiella euphorbiae

13a Galls bud- or capsule-like => 14

13b Development of inflorescence ± stunted. Flowers disfigured, unopened or ± greened and leafy (phyllanthy). E. amygdaloides, cyparissias, epithymoides, esula, peplus, palustris: Eriophyes euphorbiae

13c Generative shoots stunted. Flower peduncles are partially shortened; variously clustered. Euphorbia spp.: Philaenus spumarius

13d Malformations of the flowers and the shoot tips. E. characias subsp. wulfenii: Aceria dalmatina

14a Gall capsule-like, up to 7 mm long and 5 mm broad, spindle-shaped or ± globular; laterally closed, often curved, with ± beak-shaped tip. Contains orange to vivid red larvae. Euphorbia spp.: Dasineura capsulae

14b The fruit is disfigured, ovoid, pea-size. E. boissieriana, cyparissias:
Dasineura euphorbiarum

14c Both bracts enlarged, inflated, compactly adpressed against each other, enclosing the aborted or disfigured flowers. Gall globular, similar to flower bud, up to 6 mm long. E. aleppica, esula & subsp. tommasiniana, falcata, nicaeensis, seguieriana: Euphorbomyia loewii

15a Malformation with brown to black sori, often together with spermogonia. Species complex of Uromyces scutellatus => 19

15b Malformations bearing yellowish sori of aecia and spermogonia; many species also subsequently develop the brown to blackish other spore forms => 16

16a Single or several shoots of the non-flowering plants are disfigured => 17

16b Malformation restricted to ± extensive parts of terminal shoot. Diseased shoot parts usually conspicuously elongated, lankier than normal ones and non-flowering. Leaves shortened, thickened, slightly broadened, pale-green; at first bearing pleasant smelling, later on stinking spermogonia; after a longer period the scattered aecidia-like sori develop on the underside. E. amygdaloides, carniolica: Endophyllum euphorbiae-silvaticae

17a Apart from the aecia and spermogonia bearing mycelium, other spore forms are also developed. Fungus monoecious => 18

17b Only aecia and spermogonia. Shoots, at first ± growing ahead, rigidly erect, abnormally elongated; exceptionally severely stunted; sometimes producing branched inflorescences with disfigured flowers. Leaves usually shortened, broadened, thickened and ± pale-green; with scattered aecia on the underside and spermogonia partially also on upper side. Fungi host alternating. Euphorbia spp.: Uromyces tuberculatus species complex

18a On E. exigua, nicaeensis subsp. glareosa: Uromyces tuberculatus

18b On many other Euphorbia spp.: Uromyces proëminens

19a On species of the subgenus Esulae => 22

19b On species of the subgenus Helioscopia => 20

20a On E. angulata, dulcis: => 21

20b On E. exigua, nicaeensis subsp. glareosa: Teliospores with minute, hardly visible warts. Uromyces tuberculatus

21a On E. angulata. Wall of teliospores densely reticulate: Uromyces bresadolae

21b On other Euphorbia spp.: Wall of teliospores delicately reticulate: Uromyces scutellatus

22a On Euphorbia species with glabrous seed coat => 23

22b Mainly on E. nicaeensis & subsp. glareosa, also on E. agraria, macroclada, petrophila. Teliospores with densely arranged very delicate warts. Uromyces sublevis

22c Mainly on E. falcata, also on E. dracunculoides subsp. glebulosa. Teliospores with coarse warts: Uromyces winteri

23a Infected leaves distinctly disfigured => 24

23b Diseased shoots hardly differ from healthy shoots. Infected leaves usually distinctly longer than normal ones. Telia bearing small warts, only visible under high magnification. E. cyparissias: Uromyces alpestris

24a Leaves on diseased shoots usually shorter and sometimes distinctly broader than those on healthy plants => 26

24b Leaves on diseased, usually elongated shoots, usually hardly disfigured. On E. seguieriana and close relatives => 25

25a Teliospores completely glabrous. E. nicaeensis, seguieriana: Uromyces laevis

25b Teliospores bearing loosely arranged small warts. E. barrelieri subsp. thessala, hyberna, macroclada, nicaeensis incl. subspp. glareosa & stepposa, seguieriana: Uromyces tinctoriicola

25c Teliospores with coarse, often coalescing warts. E. petrophila, seguieriana: Uromyces cristulatus

26a Wall of teliospores with ridges of varying length; apically provided with a distinct papilla. E. boissieriana, cyparissias: Uromyces striolatus

26b Teliospores bearing large, coarse, irregularly margined warts; apically lacking papilla. E. agraria, cheiradenia, cyparissias, esula incl. subsp. tommasiniana, exigua, lucida, nicaeensis incl. subspp. glareosa & stepposa, peplus, salicifolia, seguieriana, verrucose: Uromyces scutellatus

26c Wall of teliospores provided with small but distinct warts; apically bearing a papilla. E. cyparissias, esula: Uromyces kalmusii

1a On parts above ground => 5

1b On roots or root collar => 2

2a On roots => 3

2b Conspicuous proliferations on root collar or stems. V. faba, villosa, etc.: Agrobacterium tumefaciens

= The bacterium Rhodococcus fascians may cause “leafy galls” on V. faba

3a Roots with nodular swellings or laterally inserted nodules => 4

3b Roots on the outside not distinctly changed; temporarily bearing poppy-seed sized, lemon-shaped, white, soon brown cysts. Giant cells develop inside. Vicia spp.: Heterodera goettingiana and/ or Heterodera trifolii

4a Roots with nodular- or slender spindle-shaped to cylindrical swellings, up to about 6 mm long, bearing some lateral roots. Vicia spp.: Meloidogyne hapla

4b Rotund or cylindrical, about 2–7 mm long or compact, apically broadened, also forked or comb-like to coralloid subdivided nodules, which are inserted with narrowed base into main- and adventitious roots. Vicia spp.: Rhizobium leguminosarum

5a On inflorescences, flowers or fruits => 38

5b On vegetative parts => 6

6a Stem with localised swellings, spindle- to bulge-like or young plants at base conspicuously stunted and spongy, thickened => 32

6b Malformation of many organs terminally on shoots, or galls on leaves => 7

7a Expanded parts of shoots etiolated; internodes elongated; leaves ± reduced in size, usually paler, or internodes and leaf axis ± shortened, slightly thickened; leaf blades reduced. Malformations soon bearing fruiting sori at surface => 27

7b Malformations on single or many, normally inserted or ± clustered leaves; caused by animals => 8

8a Galls on separate leaves or on ± largely unfolded leaf blades => 9

8b Leaf completely disfigured; midrib hypertrophied; leaflets folded, pod-like Containing several orange-coloured larvae. V. angustifolia: Dasineura vicicola

8c Shoot tip distinctly stunted; the very young, hardly developed vegetative or generative organs largely stunted, swollen. Marginal leaves sessile, all basal parts strongly swollen, the peripheral leaflets increasingly developing, leaf blades rolled over their complete length or with unfolded tips only. Larvae white, non-jumping. V. sepium: cf. Dasineura viciae

8d Folded hypertrophied discoloured leaflets; contain yellow, 3 mm long midge larva. Vicia lutea: Anabremia trotteri

9a On petioles, midrib or on midrib of unfolded leaflets => 26

9b On leaflet leaf blades => 10

10a Galled leaflets conspicuously fleshly thickened. In early infestations usually all leaflets of several, clustered leaves disfigured. On older leaves only a few leaflets are galled => 23

10b Leaves not fleshly swollen; curled, curved, folded or rolled inwards => 11

11a Leaf curls or -rolls caused by aphids or spittlebugs => 19

11b Leaf folds, -rolls, curvings caused by midge larvae, thrips or mites => 12

12a Folds or rolls caused by midge larvae => 16

12b Malformations caused by gall mites or thrips => 13

13a Mite galls => 14

13b Plant largely atrophied and distorted; leaflets smaller, irregularly constricted and curved, locally discoloured or browned; ± upwardly folded or -rolled. Plant largely atrophied and distorted; leaflets smaller, irregularly constricted and curved, locally discoloured or browned; ± upwardly folded or -rolled. V. cracca, hirsuta, pannonica, sativa, sparsiflora, tenuifolia, tetrasperma, etc.: Firmothrips firmus

= Stunting of various parts is occasionally caused by the black-brown “pea thrips”: Kakothrips robustus

14a Malformations on species with tendrils => 15

14b On V. cassubica, sepium. Leaflets upwardly folded, bent, petiole ± twisted. Unidentified gall mite

15a Leaf blade of leaflet, mainly of apical leaves, rolled upwards from margin up to midrib, ± curved and deflected. V. angustifolia, cracca, sylvatica, tenuifolia, villosa: Aculus retiolatus

15b Similar malformations on V. hirsuta, tetrasperma: Aceria trifolii

16a Leaf blades of single or all leaflets folded, pod-like, over the midrib or occasionally rolled inwards; not conspicuously thickened. On glabrous Euvicia species => 18

16b Similar galls on ± pubescent species. V. villosa, cracca, hirsuta => 17

17a On V. cracca, villosa, incl. subsp. varia. Fold only slightly thickened. Larva pale flesh-coloured: Anabremia massalongoi

17b Single leaflets of mostly unfolded leaves rolled upwards over the midrib on both sides. Leaf blades not shortened. Gall wall hardly thickened, at first usually not discoloured-, later on often yellowish to brownish. Larvae pale yellow to pale orange-yellow. V. cracca: Tricholaba viciarum and/ or Tricholaba similis

17c On V. hirsuta. Leaf blade folded together upwards with only its midrib thickened. Unidentified gall midge

18a Single to several leaflets per leaf loosely bent upwards. Leaf blades almost normally developed, hardly thickened and discoloured. Larvae white to dull yellow. V. sylvatica: Lathyromyza sp.

18b On V. cassubica, dumetorum, pisiformis. Single or several leaflets of younger leaves folded upwards, only the midrib thicker and discoloured. Galled parts drying after departure of the larvae, causing the unaffected leaf blade parts to be distorted ± sickle-shaped. Unidentified gall midge

19a Malformations caused by aphids => 20

19b Leaf blades usually with several deflected, ± clustered nest-like on the stunted, also curved axis; locally strongly curled and discoloured deep-green. Vicia spp.: Philaenus spumarius

20a Aphid black => 21

20b Aphid dark-green; of considerable size; siphunculi club-like, black, like cauda and legs. V. sativa, sepium, etc., occasionally on V. faba: Megoura viciae

21a On narrow-leafed Vicia species => 22

21b On V. faba; especially at shoot tips, often occurring in large colonies; causing only stunting, no gall-like malformations. Aphid up to about 2.5 mm long, dull-, rarely brown-black: Aphis fabae

= Bulging of leaves may also be caused by Vicia-virus 1.

22a Aphid up to about 2.75 mm long, black, appearing bluish translucent through white powdering; antennae longer than half the body length; siphunculi and the about equally long oblong cauda black. V. cassubica, cracca, Paederota lutea, Vicia pannonica, tenuifolia, tetrasperma, villosa: Aphis craccae

22b Aphid variating in size; black. Froth-covered nymphs only slightly frosted. Apterous adults with glossy back. Siphunculi longer than cauda, black. V. cracca, faba, sepium, etc.: Aphis craccivora

23a Galls on V. sylvatia, cassubica => 25

23b Galls on other vetches => 24

24a Leaflets folded upwards, pod-like. Wall succulent thickened, ± discoloured, also reddened. Often on severely stunted, terminal- or lateral shoot tips already the youngest leaves become galled and clustered into conspicuous balls, up to even 30 and more mm long; in other cases unfolding leaves have been attacked and several to all, usually distinctly shortened, leaflets have sometimes been transformed into clustered, thick-walled pod-like galls. Containing several white, later on proximally ± pink-coloured larvae. Mainly on V. sativa, sepium and other related Euvicia species: Dasineura viciae

= Also Anabremia bellevoyei has been reported as causer of disfigured leaflets, but this species is inquilinous like all other Anabremia species

24b Galls similar. Larvae pale-red. V. cracca, hirsuta, tenuifolia, tetrasperma, villosa, etc.: Dasineura loewiana

24c Similar galls on various Vicia species; containing whitish-yellow larvae: Dasineura spadicea

= Inquiline of D. viciae, loewiana and spadicea: Macrolabis vicicola

25a On V. sylvatica. Unfolding young to almost full grown leaves all or only several leaflets are transformed into strongly cartilage-like thickened, pod-like galls, in cross section almost rotund, usually pale-green. Containing a single or several larvae white to yellow at maturity: Tricholaba viciobia

= Inquiline gall midge: unidentified Macrolabis sp.

25b On V. cassubica. All leaflets of one or more youngest, already isolated or unfolding leaves folded upwards, pod-like. Complete gall wall conspicuously thickened, ± discoloured or reddened. Containing several milk-white, non-jumping larvae. Unidentified gall midge

26a Up to 10 (15) mm long, spindle-shaped, thin-walled swelling with oblong larval chamber on petioles or midrib. Containing a single larva. V. cracca, ? villosa, incl. subsp. varia, dumetorum, sylvatica: Cyanapion gyllenhalii

26b Midrib weakly swollen. V. sepium: Apion sp. s. lat.

27a Infected parts, especially on leaf underside, with expanded, ± grey-white patches of branched conidiophores. Malformations almost only caused by systemic infection, partially etiolated, partially associated with shortening of diseased organs => 29

27b Malformations caused by rust fungi => 28

28a Aecia and spermogonia loosely distributed over underside of leaf; mycelium often completely pervading the ± disfigured plant; leaves conspicuously smaller and shorter, pale-green. V. onobrychioides: Uromyces valesiacus

28b Fungus repeatedly developing aecia. Spermogonia only occurring together with primary aecia. Secondary aecia cup-shaped with slightly bent margin; in small groups with 2–5 on sometimes weakly galled pads on stems or scattered on expanded, usually not disfigured parts on undersides of leaves. V. hirsuta, more rarely V. tetrasperma: Uromyces ervi

29a On several Euvicia species => 30

29b On V. hirsuta, lathyroides, tetrasperma: Peronospora ervi

30a On V. cracca and forms, resp., on V. sepium => 31

30b On V. angustifolia, sativa, villosa: Peronospora viciae

31a On V. cracca: Peronospora mayorii

31b On V. sepium: Peronospora viciae

32a Stem with tough-walled or spongy swellings, containing gall causers => 33

32b Stem on any area, mainly close to ground, with broad spindle-shaped to bulging swellings, which bear single, or several rimmed depressions on the surface, containing froth-covered nymphs. Vicia spp.: Planchonia arabidis

33a Stem, also inflorescence stalks and -midrib, sometimes also leaf axis, with slender spindle-shaped, thin-walled, often at first pale-green coloured, large-chambered swellings; containing beetle larvae => 34

33b Seedlings severely stunted. Internodes stunted, sometimes twisted, often distinctly swollen. Gall tissue spongy, necrotic. Similar infestation ± encroaching into petioles and midrib; leaflets disfigured. Swellings often one-sided, curved, wrinkled, bulging, yellowish or reddish, irregularly arranged over the internodes. V. cracca, faba, hirsuta, pannonica, sativa, tetrasperma, villosa: Ditylenchus dipsaci

34a Swellings elongate spindle-shaped, usually slightly protruding => 36

34b Galls distinct, middle parts about twice as thick as the normal organ; elongate at the internodes, more compact on nodes; about 7–10 mm long. Containing a larva with a small head capsule => 35

34c Internodes with expanded, slender swellings, about 15–25 (35) mm long, reaching twice the organ diameter. The pith, which is excavated over a length, containing a compact white maggot with black gullet: cf. Agromyza erythrocephala

35a On V. cracca, dumetorum, hirsuta, sepium, sylvatica, tenuifolia, tetrasperma, etc.: Cyanapion gyllenhalii

35b Similar galls on V. cracca: Catapion seniculus

36a Galls usually differing from the previous ones by their small size, however, not positively distinguishable without rearing of adults. V. pyrenaica, sativa subsp. nigra => 37

36b V. angustifolia, lathyroides, sativa, sepium, tenuifolia, parviflora, villosa: Apion sp. s. lat.

37a V. sativa subsp. nigra: Holotrichapion pullum subsp. aestimatum

37b V. pyrenaica, ? V. sativa, sepium. Swelling of node, about 2 mm broad, 7 mm long; inconspicuous: Holotrichapion aethiops

38a On fruits => 44

38b On inflorescences or flowers => 39

39a Malformation of the complete inflorescence or localised galls on its stem parts only => 40

39b Unopened flowers contain several white, eventually orange-coloured jumping midge larvae. V. cracca, cassubica, tenuifolia, villosa, incl. subsp. varia, etc.: Contarinia craccae

= White larvae of Ametrodiplosis viciae, living on V. cracca, belong to an inquiline of Contarinia craccae

= White larvae of Jaapiella sp. are developing together with Contarinia craccae in flower heads of V. cracca

= Orange-yellow larvae of Anabremia viciae, recorded from flower buds, are inquilines of an unidentified gall midge

40a Malformations extending over inflorescence => 41

40b Spindle-shaped, up to 15 mm long, usually yellowish-green swelling on inflorescence stalks or rachis. Containing a single larva. V. cracca, hirsuta, sylvatica: Cyanapion gyllenhalii

41a Inflorescence and flowers stunted, ± clustered, ball-like => 42

41b ll flowers of a raceme ± greened and leafy. V. hirsuta, tetrasperma: Aceria trifolii

= On V. cracca and especially V. villosa inflorescences occasionally with all flowers, usually on many racemes, variously disfigured and partially greened by viruses

42a Gall midge larvae occur between organs on stunted shoot tips => 43

42b Inflorescences and shoot tips clustered into balls of flowers, or leaves. Aphids almost black, appearing bluish because of the white powdering; also encroaching onto stems. V. cracca: Aphis craccae

43a hoot tips distinctly shortened. All inserted organs clustered into conspicuous, ± dense balls. Flower primordia, situated between young leaves with pod-like disfigured leaflets, largely stunted, variously swollen and unopened. Only exceptionally normally coloured. Within and between organs are many white larvae. V. angustifolia, sativa, sepium: Dasineura viciae

43b Axial parts of inflorescence distinctly stunted. Buds clustered into rotund, more pubescent balls; unopened or only slightly opened. Yellow larvae present between buds and rachis. V. sepium: Unidentified gall midge

44a Pods disfigured by midge larvae => 45

44b Locally variously distinctly swollen pods containing a larva with narrow head capsule. V. cracca: Apion sp. s. lat.

46a Galls on Vicia species developing tendrils => 47

46b Galls on erect Vicia species => 46

46a Pods often completely or slightly disfigured, at their surface bumpy to sometimes undulately, curved. Containing several jumping, white larvae. V faba, ? angustifolia, ? sativa: Contarinia sp.

46b Pods disfigured; locally more swollen and with mycelium inside. Containing a larva at first pale-yellow, later on orange-coloured. V. sepium: Asphondylia lathyri

47a Pod of V. hirsuta, sylvatica etc. locally distinctly swollen. Inner wall of gall with mycelium. Containing a pale- to yolk-yellow larva: Asphondylia ervi

47b Ditto on V. cracca. Containing white larvae: Asphondylia sp.

1a On inflorescences, flowers or fruits => 28

1b On vegetative parts => 2

2a On parts above ground => 3

2b Roots with spindle-shaped to nodular swellings, usually bearing some side roots. R. rubrum: Meloidogyne hapla

3a On buds or leaves => 11

3b On shoot axis => 4

4a On higher parts => 6

4b On root collar => 5

5a Nodular to walnut-, sporadically chicken egg-sized proliferations on root collar, tuberculate on surface, at first white, succulent, later on browned and woody; galls sometimes also on larger roots close to surface and on higher situated stem parts. R. rubrum, uva-crispa: Agrobacterium tumefaciens

5b Excessive branching at stem base; shoots only a few cm long, strongly succulent, variously striate, with disfigured stump-like branchings. R. uva-crispa: Rhodococcus fascians

6a Causer not occurring on gall surface => 8

6b Younger axial parts usually with many rotund- to oblong-oval pock-shaped swellings, which contain a flat causer in a rimmed depression => 7

7a Scale ± rotund; 1.2–1.6 (1.8) mm wide, dirty to brownish-grey, flat arched, with dark yellow central area. Froth-covered nymph red, mainly harmful on R. nigrum: Epidiaspis leperii

7b Scale pear-shaped, white to grey-white, up to about 2.5 (3.0) mm wide. Female wine-red. Ribes spp.: Chionaspis salicis

7c Sporadically recorded on R. alpinum, R. rubrum, R. uva-crispa: Viscum album

8a Swellings on thin axial parts, elongate, ± spindle-shaped, often inconspicuous. Caused by insect larvae boring inwards => 10

8b Conspicuous, nodular or bulging or almost witches’ broom-like malformations => 9

9a Branches, more rarely stems, with warty-nodular, usually several burr tubers. R. uva-crispa, less frequently on R. alpinum, aureum, rubrum and other Ribes species: Inducer unidentified – ? bacterium, fungus; may partially be caused by: Agrobacterium tumefaciens

9b Cauliflower-like proliferations, occurring mainly on root collar. R. uva-crispa: Rhodococcus fascians

= Sporadically witches’ broom-like malformations have been associated with the rust fungus Cronartium ribicola; aecia develop on Pinus strobus, non-cecidogenic, Uredinia and telia developing mycelium in protruding cylinders clustered on leaf underside of several Ribes species

10a Inconspicuous oblong swellings of bark, mainly visible in autumn, on young axial parts. Older larvae boring in spirals in inner bark. Rare on R. nigrum: Agrilus cuprescens

10b Similar swellings on young woody shoots; older larvae feeding in pith; whitish with dark dorsal band and brown head. Ribes spp.: Synanthedon tipuliformis

10c Midge larvae live gregariously under bark. The bark is peeling off, sometimes accompanied by a dying back of the top shoots. R. nigrum: Resseliella ribis

11a On leaves => 12

11b Young side-, also apical buds distinctly swollen, producing ‘big buds’. Infestations especially conspicuous in spring, because diseased buds only partially open, and do not unfold. R. alpinum, nigrum, rubrum, rarely on R. uva-crispa: Cecidophyopsis ribis

11c Similar terminal or lateral big buds on R. rubrum: Cecidophyopsis selachodon

= The gall mite Colomerus riberini causes silvery white erineum on the underside of the leaf of R. nigrum, and the gall mite Cecidophyopsis grossulariae causes foliar injury, cavities at vein bases, enations on leaf disk, discoloration. R. nigrum, rubrum, uva-crispa

= Leaf buds of R. alpinum swollen to almost one cm in diameter, do not unfold; caused by the gall mite Cecidophyopsis alpina. Similar swollen leaf buds of R. aureum are caused by the gall mite Cecidophyopsis aurea

12a Curls, archings or bladder -shaped swellings caused by aphids => 19

12b Expanded folds, rolls, curls, or abnormal pubescence or localised warts and bulges caused by other parasites => 13

13a Localised swellings by rust fungi => 17

13b Malformations caused by animals => 14

14a Expanded malformations => 15

14b Leaf margin with several egg capsules, soon necrotic after emergence of larvae (procecidia, oviposition scars, not true galls). R. rubrum, uva-crispa: Pristiphora appendiculata

= The yellow gooseberry sawfly Nematus ribesii lays her eggs like pearls on a string along the veins without development of procecidia.

15a Leaf folds or rolls caused by midge larvae; galls lacking additional pubescence => 16

15b Leaf blade often severely disfigured, curved, folded, irregularly hunchbacked, rolled at margins, ± abnormally haired. R. alpinum, aureum: Aceria scaber

15c Less protruding, slight bladder-like archings on leaves of R. uva-crispa: Cecidophyopsis ribis

16a On R. nigrum. Margins of still unfolded leaves ± funnel-shaped to rolled, screw-like; margins of older leaves rolled over upwards to varied extent, also folded. Leaf blade curled. Spaces in between with several, at first whitish, then yellowish or yellow larvae: Dasineura tetensi

16b Similar malformations on other Ribes species. Rolls, especially on younger, developing leaves; on many hosts more densely covered with elongate, ± hair-like structures. Assignment of causer insufficiently known. Unidentified gall midges:

a On R. alpinum: Causer questionably assigned to Dasineura tetensi.

b On R. petraeum; Folds ± thickened and reddened. Abnormal grey to brown pubescence. Containing several white midge larvae.

c On R. rubrum: several white midge larvae. “Asphondylia ribesii“. Furthermore Stroblophila aberrans which does not induce galls

d On R. uva-crispa: Leaf blades partially abnormally pubescent, containing several midge larvae, at first milky-white, eventually pale yellow are attributed to Dasineura tetensi

17a Pads or bulges bearing yellow to orange-coloured aecia => 18

17b Rotund, sometimes joined, chestnut-brown, yellowish margined weak pads, usually protruding on upper side of leaves, with 2-celled, wart-like teliospores. Frequently also on fruits. R. alpinum, nigrum, petraeum, rubrum, uva-crispa, etc.: Puccinia ribis

18a Swellings minor, almost only on main veins, with joined sori. Aecia lacking peridium, dusty, belonging to the species complex of Melampsora ribesii-viminalis

18b Similar on many Ribes species: Melampsora epitea

18c On several Ribes species also develops: Melampsora epitea var. epitea

18d Swellings always distinct, protruding on leaf underside, usually rotund, up to 10 mm across, yellowish, on upper side often red margined; developing on petioles, young stems and midrib of racemes, oblong, sometimes much larger bulges; young fruits sometimes largely covered. Aecia with cup-shaped opening peridium; often ± circularly arranged on the galls. Ribes spp.: Puccinia ribesii-caricis

19a Leaves ± rolled, curled or weakly arched; often clustered, nest-like, on shoot tips => 21

19b Leaf blades often with several, conspicuous, larger or smaller, yellowish, often deep-red speckled, strongly to broad bladder-like swollen, open, upward archings => 20

20a On R. alpinum: Cryptomyzus korschelti

20b Galls mainly on R. rubrum, rarer on R. nigrum, petraeum, spicatum, uva-crispa and others, also on many cultivated foreign species: Cryptomyzus ribis

21a Disfigured leaves densely clustered, nest-like, on severely stunted shoot tip. Wingless aphids dull on surface, antennae about half the body length => 27

21b Disfigured leaves on often only slightly shortened shoots clustered in nests, or situated distally. Body of wingless aphids glossy, antennae always longer than half the body length, often even longer than the whole body => 22

22a Aphids with club-shaped siphunculi => 23

22b Aphids with cylindrical siphunculi. 2–3 mm, pale-green to green. Siphunculi pale with darker tip, about twice as long as cauda. Antennae of fundatrixes shorter, of fundatrigenia slightly longer than body. Leaves only weakly arched and not discoloured. R. alpinum, nigrum, rubrum, uva-crispa, etc.: Nasonovia ribisnigri

23a Aphid differing from all other aphids on Ribes by its dark brown body. Leaf blades of basal leaves narrower, woody, shaded shoots disfigured, discoloured, soon dropping. R. nigrum, rubrum: Rhopalosiphoninus ribesinus

23b Aphids of different colour => 24

24a Adults with expanded brown to black dorsal pattern. Mainly on seedlings, rolling the brittle leaves but not discoloured, often developing dense nests of leaves. Aphid 2.7–3.1 mm; basic colour green. Tibiae, siphunculi and cauda black. R. rubrum: Hyperomyzus rhinanthi

24b Dorsal body part of apterous aphids lacking pigmentation, or with only minor pigmentation. Siphunculi of apterous aphids pale coloured => 25

25a Aphids pale yellowish-green, difficult to distinguish and only by microscopical examination => 26

25b Aphid green. Leaves ± rolled over their length, also arched; sometimes in loose nests. Venation yellowed or leaf blades yellowing, mosaic-like. Ribes spp., especially on R. nigrum: Hyperomyzus lactucae

= Similar malformations are caused by viruses.

26a Leaves arched, in loose nests. Aphid 2.5 mm long, glossy, pale yellowish-green, siphunculi pale, sometimes darker in the middle and at their tip, rather strongly swollen. Antennae about as long as body. R. alpinum: Hyperomyzus picridis

26b Leaves weakly arched, yellowed at veins. Occasionally in loose nests. R. uva-crispa: Hyperomyzus pallidus

26c Disfigured shoot apices, petioles and curled leaves. Ribes spp.: Hyperomyzus zirnitsi

27a Leaves accumulated at tip, in dense nests. On all wild and cultivated forms of R. uva-crispa: Aphis grossulariae

27b Similar malformations and dense leaf nests on R. rubrum, also on R. alpinum, aureum, nigrum, sanguineum, etc.: Aphis schneideri

= Sometimes the polyphagous, never gall inducing, mite Bryobia praetiosa s. lat., appear as successoria (secondary inhabitants) in early vacated galls of various aphids. From spring onwards in many food plants, especially fruit, partially as important pest, because of suction damage on unfolding, early withering leaves.

28a On fruits => 32

28b On flowers or on inflorescences => 29

29a Flower galls => 30

29b Complete inflorescence disfigured. R. alpinum: Unidentified gall midge

= Various malformations associated with greening, on several flowers of a raceme of R. nigrum, are caused by virus

30a Flowers enlarged, unopened. R. alpinum, rubrum, uva-crispa => 31

30b Flowers transformed into globular- or pear-shaped, whitish or reddish galls. Corolla strongly swollen. Containing one or more yellowish or orange-red midge larvae. R. nigrum: Dasineura ribis

31a Base of calyx succulent, pale yellow to red; corolla and stamens hard. Larvae often gregarious, at first white, then yellow to orange-coloured. Galled flowers dropping after larvae complete development. R. uva-crispa: Contarinia ribis

= The N-Am gall midge Rhopalomyia grossulariae has been recorded on Ribes grossularia

31b On R. alpinum, rubrum. Flowers enlarged, unopened. Unidentified gall midge(s)

32a Galls caused by fungi => 34

32b Galls caused by insects => 33

33a Immature fruits variously disfigured, up to twice the normal size. Containing a single to five orange-coloured larvae. R. uva-crispa: Unidentified gall midge

33b Fruit strongly swollen or elongated and narrowed. R. nigrum: Pachynematus pumilio

34a Fruit wall often with several wart-like pads, a few mm long, on which the telia develop. Ribes spp.: Puccinia ribis

34b Infected fruits often bulging on expanded areas. Many aecia on pads. Sori occasionally also on fruit stalks and stalks of fruiting racemes. Ribes spp.: Puccinia ribesii-caricis

1a On above-ground parts => 4

1b On root, root collar or basal stem parts => 2

2a Malformation larger than 10 mm => 3

2b Root with nodular swellings. P. communis: Meloidogyne hapla

3a Roots, including the older ones, with cancer-like, and. buckled enlargements or rotund swellings. P. communis, nivalis: Eriosoma lanigerum

3b Root, root collar or also basal stem parts with hazelnut- to egg-size or even larger, tuberculate proliferations, which occasionally coalesce into voluminous complexes. P. communis: Agrobacterium tumefaciens

4a On flowers or fruits => 28

4b On vegetative organs => 5

5a On leaves or buds => 10

5b On lignified parts => 6

6a Predominantly on stem parts, occasionally on thicker branches => 7

6b On thicker branches, less frequent on stems, variously slightly spindle-shaped, swollen. From the galls develop: Viscum album

7a More or less open, rimmed cancer wounds on thicker branches => 9

7b Mainly closed cancers on shoot axis, especially on younger trees, or irregular depressions on bark of younger shoots => 8

7c Midge larvae cause woody, plurilocular galls on twigs. P. communis: Apiomyia bergenstammi

8a Bark of younger stems with irregular rimmed depressions, containing causer beneath a 1.2–1.6 (1.8) mm long, dirty-grey, rotund scale. P. amygdaliformis, communis and forms: Epidiaspis leperii

8b Occasionally also on Pyrus species in similar galls beneath a pear-shaped scale up to about 2.5 mm long: Chionaspis salicis

8c Local, according to the organ’s development, usually closed cancer-like proliferations, especially on stems of younger trees or on thinner branches. P. communis: Eriosoma lanigerum

9a Irregular, eventually open cancer wounds, developing from proliferations and thickenings of bark; sometimes containing several lepidopteran caterpillars eating bark and sapwood. P. communis: Enarmonia formosana

= The clear-wing moth Synanthedon myopaeformis, which lives mainly on apple is an occasional inhabitant of cancers, but do not cause them.

9b Expanded open cancer wounds caused by fungi: Neonectria ditissima

10a On leaves => 11

10b Buds transformed into a globular to conical, yellowish, multi-chambered, woody gall. If strongly infected, stunting of shoot and accumulation of galls into a larger, irregular clustering. Each chamber containing a single larva. P. communis, salicifolia, syraica: Apiomyia bergenstammi

11a Galls of indefinite shape. Leaf blade extended and variously disfigured; folded, ± irregular and without particular thickening, only loosely rolled inwards, variously bulging swollen or ± curled => 19

11b Gall constant, locally ± defined; narrow or tough marginal roll; callosity, pock, pustule, abnormal pubescence or local, strictly defined bulges => 12

12a Narrow, restricted to edge roll of margin or thick-walled upward roll of the complete leaf blade => 18

12b Gall formation on the leaf blade => 13

13a Bladder-like enlargement, bulges, pocks or pustules => 14

13b Felt-like, initially yellowish or reddish, later on brownish pubescence, mainly of leaf underside. Hairs long, cylindrical, blunt, bent. P. communis: Unidentified gall mite

14a Callosities, pucks or pustules => 15

14b Up to 10 mm broad, pale-, later on yellowish-green, soon blackening, upward arched bladders, single or in groups. At maturity of fungus densely covered with pink-coloured asci. Exceptionally also on floral parts. P. communis, especially cultivated-, less abundant on wild forms, also on P. amygdaliformis: Taphrina bullata

= Various archings of leaf might be caused by viruses.

15a Rotund to elongate spindle-shaped, yellowish to orange-red bulges, predominantly partially including the main venation. Rust fungi => 16

15b Initially yellowish, ± red tarnished, later on brownish to 5 mm broad, per leaf blade usually many, irregular pocks, protruding on both sides. Exit underside. The mites live in enlarged intercellular spaces of the swollen leaf parenchyma. Pyrus spp.: Eriophyes pyri

= Warts on the leaves, hollow on the underside are caused by the gall mite Eriophyes pseudoinsidiosus. They are the result of sucking damage to the leaf while still in the bud stage. P. communis

15c Translucent usually solitary pustules on the leaf blade or midrib, visible on both sides, vacated by eclosing larvae (procecidia: oviposition scars, not true galls): Pristiphora abbreviata

16a Swelling slightly arched. The cylindrical peridium of aecia developing from the bulge opens at apex and frays out. Telia on Juniperus communis etc. => 17

16b Swellings very distinct. Peridium of aecia egg- to cone-shaped. Unopened at apex, opening with longitudinal slits. Pyrus spp.: Gymnosporangium sabinae

17a Minor swellings. Aecia often hardly developed. Spores 19–26 x 19–22 μm. Gymnosporangium confusum

17b Swellings and aecia usually distinct. Spores 22–30 x 18–26 μm. Pyrus spp.: Gymnosporangium clavariiforme

18a Usually both leaf halves, tip excepted, from margin often to midrib rolled upwards. The rolled part arched, thickened, ± yellowed or reddened, soon browned. Galls predominantly on terminal leaves of suckers or young trees. Larvae often many, white or reddish. Pyrus spp.: Dasineura pyri

18b Similar galls on Pyrus salicifolia. Only one cream coloured larva develops in a gall. It is not clear if it is a gall causer or inquiline in galls caused by Dasineura pyri: Macrolabis pyricola

18c Leaf blades of extending leaves remain unrolled up to midrib. Containing a yellow black-headed larva. Pyrus spp.: Anthonomus spilotus

18d Upward roll narrow, compact, hardly thickened. Leaf blade sometimes darker discoloured. Pyrus spp.: Epitrimerus marginemtorquens

19a Malformations caused by aphids => 20

19b Malformations caused by psyllids or gall mites => 21

20a Leaf blade more or less stunted and browned, weakly rolled. Usually many leaves are infected on the ± stunted shoot tips. Pyrus spp.: Epitrimerus pyri

= Similar malformations are caused by thrips. Taeniothrips inconsequens lives on Pyrus and also in a similar way on other hardwoods

20b Leaves variously slightly to spirally deflected, curled and discoloured. Pyrus spp.:

a Cacopsylla pyrisuga ‒ The only psyllid harmful on pears.

b Cacopsylla pyricola – Galls similar, but facultative.

c Cacopsylla pyri – Gall-like malformations exceptional, only on young plant parts; infestation of older leaf blades results in spotting and browning of prematurely dropping leaves.

21a The disfigured leaves are ± uniformly distributed on the stunted shoot tip => 25

21b Infected leaves usually ± clustered at the shoot tip => 22

22a Aphids pale to dark-green or reddish-brown to brown. Apterous aphids powdered or dull; dorsal side at most with some pigmented spots => 23

22b Aphid black-brown with pale legs; apterous adults with dark pigmented glossy backs, grey powdered as froth-covered nymphs. Leaf roll very variable, in spring; midrib often circular-, spirally- or screw-like rolled. Leaf blades variously stunted, ± yellow marbled or discoloured. P. communis: Melanaphis pyraria

23a Aphids reddish-brown to brown, covered with wax powder => 24

23b Aphid leaf-green, lacking wax powder, with rather long dark siphunculi; on leaf underside and on shoots. P. communis: Aphis pomi

23c Occasionally observed as causer is: Rhopalosiphum oxyacanthae

24a Leaves loosely or strongly deflected; midrib contorted in loose spiral. Leaf- cluster loose; at latest vacated by end 5. Aphid yellowish-green, with dark-green, segmentally striated pattern on back, weakly grey-powdered. Producing red juice when crushed. Pyrus spp.: Dysaphis pyri

24b A very close aphid lives in similar ± triangular bag-like rolled malformations. Galls still inhabited in 7, 8; locally serious pest: Dysaphis reaumuri

25a Aphids green or brown. Leaves yellow; along the midrib almost bag-shaped, more rarely rolled-folded, ± marbled => 26

25b Aphids black. Leaves on the usually slightly stunted shoot tip spoon-shaped deflected and more strongly rolled at margin. On the shoot tips of seedlings or coppice. Aphis fabae

26a Immature alates produced by brown fundatrices => 27

26b Immature alates produced by green fundatrices, with a double row of dark green spots: Anuraphis farfarae

27a Galls indistinguishable from previous species: Anuraphis subterranea

27b In galls indistinguishable from previous species lives the presumably inquiline Anuraphis catonii

28a On fruits => 29

28b Flowers severely stunted. Corolla unopened covering the eaten inner parts. Containing a single larva. P. communis, amygdaliformis: Anthonomus pomorum

= Anthonomus piri deposits its eggs already in late autumn in flower bud primordia, larvae develop in early spring, destroying many flower primordia, however, without causing galls.

29a Infected fruits swollen calabash-like; initially significantly faster growing than normal ones; up to hazelnut size; hence distinguishable from the only half as large healthy ones. Often ± buckled, soon black-spotted, inside spongy, later hollow, then dropping. Containing gregarious larvae, white to pale yellow, jumping. P. communis, salicifolia: Contarinia pyrivora

29b Younger or older immature fruits with wart-shaped soft swellings, usually less than 5 mm across, occasionally coalescing, pale-green. P. communis: Eriophyes pyri

= Conspicuous, bump-shaped, hard fleshy swellings on the ± deformed fruits are caused by punctures of the bug Closterotomus fulvomaculatus

1a On above-ground parts => 3

1b On roots => 2

2a Rotund, cancer-like proliferations on roots and root collar, several cm long, at first glabrous on surface then ± bumpy, soon lignifying, laterally inserted, often many and variously coalescing. Especially on young plants. Malus spp.: Agrobacterium tumefaciens

2b Roots with nodular, rotund or oval swellings, up to about 7 mm long ± cracked or bulging, eventually bursting; close to ground level, even on older roots groups often coalescing, stimulated new tissue developing into voluminous cancer-like growths. Occupied by white woolly aphids. Malus spp.: Eriosoma lanigerum

2c Nodular, usually smaller, glabrous swellings. Malus spp.: Meloidogyne hapla

= The red bud borer Resseliella oculiperda damages rootstocks of cultivated roses and apples when these are grafted with scion buds by “shield budding”.

3a On leaves, buds, flowers or fruits => 7

3b On stems, branches and twigs => 4

4a Galls on or in the bark => 5

4b Expanded spindle- or club-shaped swellings on branches or stems. Malus spp.: Viscum album

= Witches’ broom-like malformations at the end of shoots are partially caused by virus diseases. The early developing malformations are distinguished by their discoloured leaves, which are longer stalked and have larger stipules than the normal ones.

= Cancer-like structures usually develop as excessive callus proliferations in over-sensitive responses. Also many wound-calluses may develop into smaller, similar, but locally depressed nodules.

5a Younger plant parts with nodular, or older ones with cancer-like proliferations of irregular nature => 6

5b Up to 2 mm long, lenticular, bulging-rimmed depressions on bark of young shoots, in case of heavy infestation slightly swollen. Each depression containing a red insect, covered by a ± rotund scale, 1.3–1.6 mm wide: Epidiaspis leperii

5c In similar, but deeper depressions on the swollen bark: Chionaspis salicis

6a Nodular swellings of bark, up to walnut-size, later on erupting and cracking; often many coalescing and developing expanded cancer-like swellings. Especially on young trees. Containing white powdered aphids in cracks. Spring to autumn. Malus spp.: Eriosoma lanigerum

6b Buckled margined cancer wounds, increasing on older branches and of very varied shape. At first, on younger parts, because of the strong regenerative ability of host, usually transformed into variously delimited, bumpy, ± closed, nodular tumours; later on, the central tissue decays on older branches resulting in fissured cancer wounds, open, into the wood: Neonectria ditissima

= Caterpillars of clear-winged moth Synanthedon myopaeformis or Enarmonia formosana are occasional inhabitants of cancers, but do not cause them.

= Also the sac fungus Neofabraea perennans has occasionally been reported as inducer of Nectria-like cancers on apple and pear.

7a On buds, flowers or fruits => 29

7b On leaves => 8

8a Malformations associated with various curls, swellings, folds or loose rolls, which often involve the complete leaf blades sometimes of many terminal leaves => 15

8b Narrow, compact marginal rolls or leaf blades with locally defined galls => 9

9a Narrow roll of leaf margin => 13

9b Pock-like or slightly bladder- to bulge-shaped galls, with erinea => 10

10a Pocks, bulges, or minor bladder-like swellings => 11

10b Irregular, initially reddish white, then brownish erinea, mainly on leaf underside, usually along venation. Hairs long, cylindrical, blunt, spiral. Mainly on M. sylvestris, less so on M. pumila, etc.: Phyllocoptes malinus

11a Malformations caused by fungi => 12

11b Leaf blades with many ± oval pocks, usually 2–4 mm across, protruding from both sides. M. communis, sylvestris, etc.: Eriophyes mali

11c Vagrant mites on the underside of the leaves. At high densities rusting may occur. M. domestica, pumila, sylvestris: Calepitrimerus baileyi

11d Translucent pustules, visible on both sides, soon collapsing, in 5, 6, usually on the midrib, are procecidia of the black pear sawfly, occurring mainly on pear, occasionally on apple. Pristiphora abbreviata

12a Yellowish pads rotund on leaf blade, ± spindle-shaped on midrib, protruding on underside, later on with oblong-cylindrical, often curved aecia. Peridium thread-like rupturing onto base. Malus spp.: Gymnosporangium tremelloides

12b Rarer on apple are the cylindrical, tuft-like aecia of Gymnosporangium cornutum

12c Minor, usually several per leaf blade, covered with ± radiating, blackish mycelium, rotund, up to 7 mm long upward archings on young leaves of hawthorn shoots. Malus spp.: Venturia inaequalis

13a Rolls of leaf margin lacking conspicuous pubescence => 14

13b Expanded, border-like upward rolls with abnormal pubescence, occasionally encroaching well into the leaf blade. M. sylvestris, etc.: Phyllocoptes malinus

14a Similar, but not conspicuously pubescent roll of leaf border. M. pumila, sylvestris: Eriophyes malimarginem-torquens

14b Leaves of young shoots with cartilaginous thickening, often on both margins, usually discoloured yellowish or reddish, often running parallel to midrib, usually resulting in an upward roll. Inside the brittle tube are several, at first cream-white, then red midge larvae. Malus spp.: Dasineura mali

= Inquilinous cream-coloured midge larvae living in galls of Dasineura mali: Macrolabis mali

15a Malformations caused by aphids => 19

15b Malformations attributed to other causes => 16

16a Malformations caused by mites, psyllids or spittlebugs => 17

16b Several terminal leaves on shoots stunted, disfigured, their margins ± bent upwards, slightly thickened and often completely covered by a sometimes cotton wool-like, white mycelium. Malus spp.: Podosphaera leucotricha

17a Malformations caused by mites or spittlebugs => 18

17b Leaves variously curled and deflected; with many small spots, soon turning brown, caused by suction feeding of flattened, yellowish to greenish froth-covered nymphs, up to 1.5 mm long, exuding copious honeydew. Malus spp.: Cacopsylla mali

17c Very similar infestation: Cacopsylla picta

18a Leaf blade stunted and soon browned due to many suction spots; in cases of severe infestation both halves are strongly folded upwards and their margins may even come in contact. Infected shoots die off prematurely. Malus spp.: Aculus schlechtendali

= Predating gall midges: Arthrocnodax mali, wissmanni.

18b Stems of saplings shortened. Leaves ± clustered and converging, leaf blades crumpled, locally deep-green. Containing a froth-covered nymph. M. pumila: Philaenus spumarius

19a Leaves folded along their midrib or rolled, distinguished by yellowish to reddish discolouration => 23

19b Rolls of margin or folds without particular thickenings => 20

20a Variously disfigured leaves are loosely inserted often on only slightly stunted shoot ends => 22

20b Shoot tip conspicuously shortened => 21

21a Many leaves on the ± stunted, curved and etiolated shoot tip are strongly deflected and ± curled. Dark-green aphids, ± 2 mm long, with long, dark brown-black siphunculi feed on underside of leaves and move onto shoots. Malus spp.: Aphis pomi

21b Similar galls, only inhabited in spring. M. pumila: Allocotaphis quaestionis

22a Downward leaf roll and curling caused by black aphids. M. pumila: Aphis fabae

22b Midrib of leaves sometimes loosely contorted. Leaf blades deflected downwards, often strongly rolled, making loose clusters; aphid yellowish-green with segmental dark-green striping dorsally and with dark siphunculi that are pale only at the tips. Malus spp.: Rhopalosiphum oxyacanthae

23a Leaves often crookedly rolled downwards on only one side, usually up to midrib, coarsely undulate at tip; discoloured yellowish or mainly intensively red => 24

23b Young leaves at shoot tip strongly rolled, often on both sides, almost intestine-like or ± spirally bent, discoloured yellowish. Often many young shoots infected; in which case the plants look bushy. Malus spp.: Dysaphis plantaginea

24a Aphid galls are usually vacated by end of June; galled leaves already drop in July => 25

24b Galled leaves stay on tree; also inhabited during summer. Malus spp.: Dysaphis devecta

25a The roll galls occurring on cultivated apple and relatives of the next aphids do not differ morphologically; the closely related aphids are only microscopically distinct; main difference is their host alternation. Furcula (mid-thoracic fork) of the wingless aphids is always bifid. Summer hosts are Polygonaceae, Apiaceae or Plantaginaceae => 26

25b Furcula not bifid. Summer hosts are Valeriana species. Malus spp.: Dysaphis brancoi

26a Aphid alternating to Apiaceae or Plantago => 27