1a On parts above ground => 2

1b Roots, especially close to stem, with conspicuous, irregular, ± nodule-shaped, massive proliferations. B. pendula, pubescens: Agrobacterium tumefaciens

2a On catkins or fruits => 51

2b On vegetative plant parts => 3

3a On leaves => 18

3b On shoots or buds => 4

4a On shoots => 6

4b Bud galls => 5

5a Buds greatly enlarged; scales loosely adpressed, with outward tips, brownish, grey-silky pubescent. Gall often persistent, sometimes already developing early into small, compact witches’ brooms. Betula spp.: Acalitus calycophthirus

5b Leaf buds swollen, disfigured to a variable extent. B. pendula: Eriophyes leionotus

5c On buds of B. pendula is also reported: Unidentified gall midge

6a On thinner twigs => 12

6b On older stems or branches => 7

7a Bushy malformations in or on the branches => 8

7b Bark of thicker stems or branches with nodule-shaped or open, rim-like margined cancers. Neonectria ditissima

= Globular, several cm large wood balls or the giant wood cancers, observed occasionally have unknown causes and are not true galls.

8a Complete shoot systems are disfigured into conspicuous witches’ brooms, or young twigs with ± pronounced malformations. Usually only the leaves are covered by a short lanuginose grey-white layer of asci => 9

=Regarding compact small witches’ brooms => 5

8b Branches with nodular swellings which give rise to Viscum album

9a Fungi only exceptionally cause witches’ brooms. Northern species => 11

9b Fungi usually cause pronounced witches’ brooms => 10

10a Fungus scattered on many birches. Witches’ broom persistent. Leaves usually lighter coloured than the normal ones, occasionally enlarged but hardly thickened. Betula spp., incl. cultivated foreign species. Taphrina betulina

10b ngus frequently causes pronounced witches’ brooms, but may also develop on many disfigured, ± yellowing leaves without conspicuous malformations of the branches. Taphrina nana

11a Asci with stalk cells. Witches’ brooms only caused exceptionally; the fungus is merely located on darker green areas, on the underside sometimes ± rust-brown discoloured, usually on undisfigured leaves. Taphrina splendens

11b Asci without stalk cells. The fungus is located on often many, sometimes slightly enlarged, soon yellowing leaves of the infected plant, only exceptionally do witches’ brooms disfigure shoots. B. glandulosa, nana, pubescens, x alpestris. Taphrina bacteriosperma

12a Inducer inside the malformations => 14

12b The flat inducers are located in rim-surrounded depressions in the bark and, in case of heavy infestation, sometimes additionally on swollen or disfigured twig => 13

= Minute elevations on twigs of B. pendula, caused by the damselfly Chalcolestes viridis, are not true galls

13a Scale ± pear-shaped, 2.5–3 mm long, white to grey-white, females wine-red. Betula spp.: Chionaspis salicis

13b Scale ± rotund, 1.2–1.6 mm across, whitish to brownish-grey, with dark-yellow median spot. Insect red. Betula spp.: Epidiaspis leperii

14a Shoots with elongated spindle-shaped or ± distinctly separated, nodule-shaped swellings, up to 1 cm wide => 15

14b Young shoots with various proliferations of walls of wounds. Betula spp.: Cryptorhynchus lapathi

= Large nodular outgrowths up to several cm, like those found laterally on young shoots, cannot be attributed to a particular cause and could be considered as teratologies.

15a Inducers inhabit only galls on first-year twigs; galls on woody twigs vacated or occupied by successoria (secondary inhabitants) => 16

15b Older shoots with spindle-shaped thick swelling, up to 50 mm long and 15 mm wide. Gall extending over several internodes, broadest in the upper part caused by a swelling of the woody part; bark only slightly swollen. Inside a long tunnel. B. pendula, pubescens: Unidentified lepidopteran

16a Axis swollen at the top of the shoot => 17

16b Swelling situated below a node, rotund or more or less spindle-shaped, 5–10 mm long; broadest at the node. In a long tunnel inside the pith is a pale-green to greenish-yellow caterpillar with a pale brown head capsule. Exit hole in the leaf axil. Betula spp.: Epinotia tetraquetrana

17a Axis swollen at the top of the shoot. B. pendula, pubescens: Acleris notana

17b Young shoot with a slender swelling on all sides which usually starts below the top and expands downwards over several internodes. Internodes sometimes ± shortened. A tunnel in the pith contains a single caterpillar. B. pendula, pubescens and related species. Heliozela hammoniella

18a Galls on the leaf blades => 23

18b Malformations only on petioles and leaf veins => 19

19a Swellings hardly 2 mm across or smaller => 21

19b Galls several mm long => 20

20a Petiole shortened, over its whole length thickened; at the base of the leaf blade an oblong-elliptical excision. Betula spp.: Heliozela hammoniella

20b Main-, or more rarely lateral veins, occasionally also the petiole, with spindle-shaped, glabrous, hard, pale-green or often also ± purple-red swellings especially visible on the undersides. Each gall contains one single larva; in largely coalesced galls several white, later on pale red larvae. B. pendula, pubescens, x intermedia: Massalongia rubra

20c Much weaker, only up to about 3 mm long, pale green, thin-walled swellings, developing usually solitary per leaf blade on first or second order lateral veins. Containing a single white larva. B. pendula: Unidentified gall midge

21a Each swelling contains a single egg; the emerging larva leaves the rapidly collapsing egg capsule. “Procecidium” (oviposition scars, not true galls ) => 22

21b Up to 2 mm long, corn-like or more wart-like galls, up to 1 mm high, on petioles and veins. Cavity with some short, 1-celled hairs. B. pendula, pubescens: Cecidophyopsis betulae

22a Petiole, more rarely also the midrib, with two rows of egg capsules. B. pendula, pubescens: Hemichroa crocea

22b Egg capsules arranged in one row on the midrib or also on the side veins. B. pendula, pubescens: Craesus septentrionalis

22c In similar way develops on birches Craesus latipes

23a Leaf blade with weak to strong spoon- or bladder-like swellings caused by mites, aphids or fungi, whose asci develop on the galls => 40

23b Malformations different => 24

24a Galls mainly on unfolded leaf blades => 27

24b Leaves folded or rolled upwards => 25

25a Malformations without abnormal pubescence => 26

25b Leaf margin rolled upwards; on older leaves often only at the leaf base; early infected leaf blades may be completely taken up in a leaf roll with densely pubescent surface. Unidentified gall mite

26a The leaf blades of young leaves do not develop completely and remain mostly folded upwards. Midrib and basal part of the side veins thickened, pale green or ± reddened. Several yellowish-white larvae. B. pendula: Resseliella betulicola

= The white larvae of the gall midge Dasineura betuleti live, probably as inquilines, in similar galls which may be caused by the previous specie

26b Leaves close together at the tips of young shoots, severely stunted, rolled, curled and yellow-green. Unidentified thrips

= Stunting of leaves are occasionally caused by the thrips Mycterothrips consociatus

27a Galls situated in the leaf blades => 28

27b Teeth of the leaves with rapidly collapsing egg capsules after the larvae have emerged. “Procecidia” (oviposition scars, not true galls). B. pendula, pubescens: Pristiphora testacea and/or Arge pullata

27cPredominantly on Salix, occasionally on Betula: Pristiphora melanocarpa

28a Leaf blade with ± expanded felt-like cover => 34

28b Leaf galls of roughly defined shape, usually not excessively pubescent => 29

29a Galls wart-, nodule- or ± pouch-like, under 2 mm wide => 31

29b Parenchyma galls; rotund, weakly protruding on both leaf surfaces, about 3–4 mm wide; yellowish, usually red-rimmed. Often several per leaf => 30

30a On B. pendula, pubescens. Each gall contains an initially white, eventually sulfur-yellow larva. Galls usually several per young leaf. Anisostephus betulinus

30b On B. pendula, pubescens. Older leaf blades with solitary or only a few, very flat, concolorous, hardly protruding parenchyma galls. Containing a single pale to lemon-yellow larva. Massalongia betulifolia

30c On B. nana. Similar thick-walled parenchyma galls, strongly arched on the underside. Each gall contains a single orange-reddish larva. Massalongia bachmaieri

31a Galls larger than 1 mm => 32

31b Galls wart-shaped, smaller than 1 mm, golden-yellow translucent, often many on the basal leaves or stems. B. nana, pendula, pubescens: Synchytrium aureum

32a Galls persistent, tough-walled => 33

32b Leaf tips with irregularly distributed egg capsules on the underside which rapidly collapse after the larvae have hatched. “Procecidium” (oviposition scars, not true galls). Betula spp.: Nematus cadderensis

33a Leaf blade with, scattered glabrous nodules, about 1–1.5 mm long, ± reddish, later on browned, protruding strongly on the underside and with an exit hole closed by a rim of rigid hairs; wall of the cavity glabrous. B. pendula, pubescens: Eriophyes leionotus

33b otund, up to 3 mm high, ± pubescent pouch-like protrusions on the leaf upper side, predominantly close to the margin, rarer in the vein axils; wall of the cavity provided with yellowish-white, ± cylindrical, rigid hairs. B. pendula, pubescens: Acalitus longisetosus

34a Hairs cylindrical => 36

34b Hairs club- to toadstool-shaped => 35

35a Erinea dense, ± irregularly margined, initially often intensely red, eventually ± browned, predominantly on upper side, occasionally also on the underside. Hairs irregular head-shaped or ± toadstool-like. Betula spp.: Acalitus longisetosus

35b Dense wine-red coloured erinea with irregular head-shaped hairs; predominantly at the leaf base or along the veins. B. nana: Aceria vinosa

35c Erinea usually on leaf underside, sometimes on both sides, rarely on upper side; initially whitish, later on yellowish, eventually rust-coloured or brownish. Hairs head-shaped, usually longer stalked than those of the previous species. B. humilis, nana, pendula, pubescens, etc.: Acalitus rudis

36a Erinea on the leaf underside, in arched protrusions, predominantly in vein axils => 39

36 Erinea on the leaf underside, also in arched protrusions, but free in the leaf blade or near the margin, or erinea predominantly on petioles or leaf veins => 37

37a Erinea mainly in areas on the leaf blade => 38

37b White, also reddened erinea predominantly on the petioles and on the venation of the leaf base or extending from the stalks into the leaf base venation. B. pendula, pubescens, pubescens var. glabrata, etc.: Eriophyes leionotus

38a Leaf blades of B. nana predominantly close to the margin with ± discoloured archings on the upper side, which contain purple-red to almost whitish felt masses with cylindrical hairs. Aceria fennica

38b Leaves of B. pubescens with upward archings predominantly on the leaf blade, more rarely in the vein axils, which display on the underside ± dense, cylindrical, rigid, whitish-yellow hairs. Acalitus notolius

39a On the upper side arched, glabrous or more rarely weakly pubescent protrusions in the vein axils containing on the underside cylindrical, soon browned, densely packed, not spiralling hairs. B. pendula, pubescens: Acalitus longisetosus

39b Erinea relatively loose, with cylindrical, pointed contorted hairs; usually on the underside in rotund to oval, ± heavily pubescent pale green bladders, situated predominantly in the vein axils at the base of the midrib, more rarely close to the margin or on the leaf blade. B. pubescens & var. pumila, x intermedia: Eriophyes lissonotus

39c In similar galls, but containing beads or short finger-shaped blunt hairs. B. pubescens & var. pumila, x intermedia: Eriophyes leionotus

40a Galls caused by aphids or mites => 44

40b Malformations caused by fungi which fruit on the gall surface => 41

41a Malformations often only locally; on single or several leaves of a shoot => 43

41b Leaves on the infected, systemically attacked shoots often hardly disfigured, although completely or substantially attacked. Leaf blades usually paler, ± slightly enlarged and slightly arched upwards, without conspicuous thickening => 42

42a Fungus frequent or with only boreal-alpine distribution. Initially infections of fungi which occur on the same plant or in the same host population in conspicuous witches’ brooms. Asci with stalk cells

a Leaf blades of young shoots pale green, sometimes slightly enlarged. Axial parts ranging from not disfigured to witches’ broom-like malformations. Betula spp.: Taphrina betulina

b Similar malformations. Betula spp.: Taphrina nana

42b Usually witches’ broom-like malformations develop without simultaneous malformations of shoots and leaves

a Asci with stalk cells. Malformations rarely on axial parts, usually minor on leaves. Betula spp.: Taphrina splendens

b Asci lacking stalk cells. Leaves of the infected shoots often yellowing, sometimes with slightly enlarged leaf blades. Betula spp.: Taphrina bacteriosperma

43a eaves often with conspicuous yellowish or reddish discoloured, thickened, bladder-like swellings. Asci lacking stalk cells. Betula spp.: Taphrina carnea

43b Minor swellings, sometimes several per leaf on early infected young leaves. Infection sites about 2–10 (15) mm across, rotund, ± discoloured. Asci with stalk cells. Betula spp.: Taphrina betulae

43c On leaves, probably non-cecidogenic. Betula spp.: Melampsoridium betulinum

44a Malformations caused by aphids => 45

44b Leaves ± spoon-shaped bent downwards. Leaf blades soon yellowish to brownish discoloured; on the underside with free-living mites. Betula spp.: Epitrimerus subacromius

45a Leaves to various extents folded or curled => 46

45b Leaves with irregular, conspicuous bladder-like swellings, up to 10 mm high, upwardly directed, which occupy a major part of the leaf blade. Aphid egg-shaped, dark purple-red, covered with wax. B. x alpestris, pendula, pubescens: Hamamelistes betulinus

46a Aphids in various shades of yellow or green, or (because of its banded pattern) almost black => 47

46b Aphid dull brown, 2.5–3.5 mm long with brownish transverse stripes; on the underside of irregular undulate leaves. B. pendula, pubescens: Symydobius oblongus

47a Antennae shorter than body => 48

47b Antennae longer than body. Aphid about 2.5 mm long, pale yellowish or –greenish, with yellowish or greenish spots. Younger leaves curled, in cases of heavy infestation upwardly arched. B. pendula, pubescens: Calaphis betulicola and/or Calaphis flava

48a Aphids with dark coloured or margined short siphunculi => 49

48b Aphid about 1.3–2 mm long, greenish-white to pale yellowish-green. Siphunculi very short, yellowish-white, like the also equally short wart-shaped cauda. Antennae reaching beyond the middle of the body. Infected leaves ± distinctly upwardly arched, often withering prematurely; on the underside with considerable colonies. B. humilis, pendula, pubescens: Betulaphis quadrituberculata

49a Aphids more than 2 mm long; siphunculi black or black-green; antennae half the body length => 50

49bAphid 1.5–2 mm long, almost egg-shaped, pale or yellowish-green, with broad, dark-green to brown, medially interrupted transverse bands. Antennae often shorter than half the body length. Internodes of young shoots ± stunted. Leaves curled or, in case of heavy infestation, upwardly arched. B. pendula, pubescens: Glyphina betulae

50a Aphid about 2.5 mm long, usually yellowish or greenish, deep to almost black-grey coloured by lighter or darker blackish transverse bands. Siphunculi very short, black; cauda only wart-shaped, green. Leaf margins ± downwardly bent and folded. B. pendula: Callipterinella calliptera

50b Similar malformations. Aphid about 2 mm long, pale yellow, abdomen near thorax with a wide brown-red transverse band, a large greenish-black spot behind, caudal margin brown-red. Siphunculi black-green, cauda pale yellow. B. pendula: Callipterinella tuberculata

51a Malformations visible on outside of catkins => 54

51b Malformations only visible after crumbling the female catkins => 52

52a Gall restricted to fruits, which are enlarged and paler than the healthy ones => 53

52b Galls restricted to the somewhat thickened base of the fruit scales, which are firmly connected to the spindle of the catkin. Containing a single bright orange-red larva. Betula spp.: Semudobia skuhravae

53a Fruit more or less egg-shaped, swollen, dull, more or less pubescent, wings smaller than those of healthy fruits, but distinctly developed. Exit circular, distinct. Contains a single bright orange larva. Betula spp.: Semudobia betulae

53b Fruit almost globular, swollen, glossy, glabrous, wings almost completely reduced, exit indistinctly translucent. Contains a single bright orange-red larva. Betula spp.: Semudobia tarda

= A frequent inquiline is the gall midge Dasineura interbracta, whose pink larvae adhere to the outside of the galls and feed on these galls at the expense of Semudobia betulae as well as S. tarda, larvae of which eventually die

= A less frequent inquiline gall midge: Dasineura fastidiosa, whose pale yellowish larvae adhere to the outside of the galls and feed on these galls at the expense of mainly Semudobia betulae, larvae of which eventually die

54a Caterpillars with distinct thoracic legs => 55

54b Larvae with distinct head capsules, lacking distinct thoracic legs; inside the variously stunted fruit catkins. They tunnel along the spindle of the catkin and feed both on plant tissues and on midge larvae and their galls. B. pendula, pubescens: Betulapion simile

54c Catkin enlarged, caused by gall midges. B. pendula: Unidentified gall midge

= Furthermore the aphid Callipterinella minutissima has been recorded from birch catkins.

55a Catkins shortened, appearing ± thickened, often twisted screw-like and not reaching maturity. B. pendula, pubescens: Cochylis nana

55b atkins similarly stunted. B. pendula, pubescens: Epinotia bilunana

55c Further facultative deformations are occasionally caused by the caterpillar of Epinotia tenerana

1a Leaves at the shoot tip thickened, coalesced to a gall. F. gallica, germanica, minima. Acentrotypus brunnipes

1b Tips of flowering and vegetative shoots distorted, available leaves twisted with inrolled margins, stems shortened; infected with green or yellowish aphids covered with white wax. F. arvensis, germanica, lutescens: Pemphigus populinigrae

1b Terminal swellings of shoots. Phagnalon saxatile, rupestre: Spathulina sicula

1a On parts above ground => 2

1b Nodular swellings on roots. F. carica: Meloidogyne hapla

2a Malformations of leaf blade => 4

2b Small glossy galls inside fig fruit => 3

2c ranch cankers. F. carica: Phomopsis cinerascens

3a On F. carica, cordata subsp. salicifolia, palmata, sycomorus: Blastophaga psenes

3b On F. sur: Blastophaga occultiventris

3c Terminal part of young shoots stunted; leaves folded upwards and transformed into irregular pods the margins of which touch at several places; both of the leaf blade halves may be rolled completely up to the midrib and form a succulent, brittle cylinder. External surface reddish with many reddish spots, ± coalescing if severely infected. F. elastica, benjamina, microcarpa: Gynaikothrips ficorum

3d Female florets within the fig, develop into a small, globular shining gall. F. ? benjamina, microcarpa: Eupristina verticillata

= Three more fig wasp species have been recorded in florets of syconia, viz., Blastophaga psenes, Odontofroggatia galili and Pleistodontes sp.

4a Half-globular swellings, protruding on upperside of leaf, with corresponding depression on underside, 1–2 mm across. F. sycomorus: Aleyrodes sp.

4b Leaf blade rolled upwards, along midrib, with small reddish elevations scattered on underside, and corresponding depressions on the other side. F. benjamina: Unidentified gall mite

= On F. carica the gall mite Aceria ficus causes injuries of fig buds and rolls of leaf margin and cause leaf chlorosis, rusting, bronzing and distortion, causing in premature leaf drop. The mite is involved in vectoring the ficus mosaic disease agent

4c Conspicuous leaf galls caused by thrips. F. elastica, benjamina, microcarpa: Gynaikothrips ficorum

4d Irregular, hairless swelling of the leaf, about equally protruding at both faces, ± a cm in diameter, often several coalesced in blister galls, usually considerably extended over leaf surface. Caused by fig wasps. F. microcarpa: Josephiella microcarpae

4e Small discoloured leaf galls, mature galls become thick and brown. F. benjamina, microcarpa: Horidiplosis ficifolii

1a On part of umbel or fruits => 4

1b On vegetative parts => 2

2a Galls caused by animals => 3

2b Oblong bulges on leaf veins, -stalks and stems, bearing aecia. F. campestris, communis, sadleriana: Puccinia ferulae

= Also known from Mediterranean, SE-Eu, Ferulago hosts is the rust Uromyces ferulae, with cecidogenic aecia.

3a Yellowish, wrinkled thickenings on midrib and tips of leaflets. F. campestris: cf. Ditylenchus dipsaci

3b lmost nest-like deflected larger parts of leaves, associated with curling of inserted leaflets on stunted midrib. F. campestris: Philaenus spumarius

4a Centre of stalk of (partial) umbel with one- or several-chambered tough-walled, ± club-shaped swellings. Each chamber containing a single larva. F. campestris, setifoliae: Lasioptera carophila

4b Fruits inflated, bladder-like globular, distinctly protruding above the umbel, containing a red larva. F. campestris: Kiefferia pericarpiicola

1a Galls in umbels and fruits => 2

1b Oblong swellings of variable gradation on leaf veins, -stalks, densely covered with aecia. F. communis, sadleriana: Puccinia ferulae

= Also known from Mediterranean, SE-Eu, Ferula hosts are the rusts Uromyces ferulae and Uromyces graminis, with cecidogenic aecia

1c Leaf sheath especially close to umbel inflated, bulging and swollen, succulent, often lacking leaf blade. F. communis: Jaapiella hedickei

2a Fruit swollen, rotund or pear-shaped, conspicuously bent if only one half galled. F. heuffelii: Asphondylia ruebsaameni

2b Galls in umbellules and fruits, inside wall lined with mycelium. F. communis:
Lasioptera carophila

1a On parts above ground => 2

1b Nodular swellings on main-roots, occasionally on thicker side roots. F. esculentum, tataricum: Meloidogyne hapla

2a Malformations caused by animals => 3

2b Leaf blades with conspicuously arched, pale spots, covered on underside by a down of branched conidiophores. F. esculentum, tataricum: Peronospora ducometi

3a Malformation usually of several terminal leaves, caused by aphids or spittlebugs => 4

3b Complete plant stunted, often excessively branched. Single shoots shortened at base, thickened, ± curved. Axial parts of leaves swollen. Leaf blades partially variously thickened and disfigured. Galls ± wrinkled, necrotic. Containing many eelworms. F. esculentum, tataricum: Ditylenchus dipsaci

4a Black aphids. Leaves singly or on shoot tip with several bulges, margin ± deflected. F. esculentum: Aphis fabae subsp. solanella

4b Stunting, one-sided distortion and clustering of variously disfigured leaves by infestation of stem. Infected leaf blades deflected, curled and often intense green. F. esculentum, tataricum: Philaenus spumarius

1a On leaves => 2

1b Centre of (partial) umbel or stalk of umbel ± swollen, globular to club-shaped. Gall one-to multi-chambered, inner wall covered with mycelium. Each chamber containing a red larva. Lasioptera carophila

2a Bulge-shaped pads bearing yellowish spermogonia and aecia on petioles, -midrib and main veins. Puccinia sileris

2b Leaf tip undulately curved. Trioza sp.

1a On parts above ground => 2

1b Roots with nodular swellings. L. squarrosa, myosotis: Meloidogyne hapla

2a Large parts of plant disfigured. Excessive leafiness, abnormal pubescence or inflorescence stunted, ± densely pubescent, flowers stunted or partially leafy. L. squarrosa, myosotis: Aceria eutricha

2b Yellow, also reddish to brown nodules developing from a single cell, occasionally coalescing and sometimes with additional swelling on stems and leaf veins arranged in ridges or crusts. L. squarrosa, myosotis: Synchytrium myosotidis

1a Stem with about 1–5 mm long bulges, 1–2.5 mm thick, irregular tuber- to barrel-like, sometimes distorted, at first lead-grey translucent, with black dusting after rupturing. Microbotryum koenigiae

= The rare ovary smut Microbotryum picaceum with irregular globular to elliptic spores attacks fruits, which are soon destroyed. Wall densely covered with minute punctated warts

1a Galls on roots, sometimes encroaching onto basal stem part => 2

1b Spongy, pale green swelling on basal shoot parts; galls occasionally also encroaching onto leaf midrib. Ditylenchus dipsaci

2a Galls conspicuous, more or less globular to tuberous => 3

2b Side roots with slender spindle-shaped swellings on all sides, bearing side roots. Meloidogyne hapla

3a Roots with rotund swellings, containing a single, curved beetle larva in chamber. Rhinusa collina

3b Similar, irregular tuberose, compact swellings on upper part of main root, sometimes on basal stem part or terminally on side roots. Galls contain many black spores. Melanotaenium hypogaeum

1a Leaf blade on the upperside with many pouch-shaped galls, ± 2.5 mm across, at the base somewhat constricted, usually rather strongly pubescent ± reddish. Opening on the underside, densely white tomentose. J. consanguinea, mollis: Aceria brevicincta

1b Receptacle hardened, sometimes disfigured, slightly swollen. J. mollis.
cf. Tephritis frauenfeldi

1a Malformations of shoot tips, stems or capitula => 2

1b Complete plant ± disfigured and sometimes measuring only several cm. Axial parts of non-flowering shoots stunted, causing leaves rosette- or tuft-like clustered, broadened and abnormally pubescent. Leaves of flowering shoots, as well as bracts of capitula ± broadened and strongly abnormally pubescent. Flowers aborted, sterile, ± greened or leafy, pubescent, sometimes excessively branching. Aceria enantha

2a Spindle-shaped swelling of stem or malformation of flower head => 3

2b Shoot tip stunted, leaves accumulated, clustered at tip, rosette-like. In pith an about 8 mm long cavity containing a single larva. Napomyza lateralis

3a Stalk below flower head irregularly thickened, spongy, with wrinkled surface, ± bent. Unidentified eelworm

3b Flower head distorted and etiolated. Thrips major

1a Expanded galls caused by rust fungi which fruit on the outside => 2

1b Wart-shaped, pearl-like gall consisting of only a few cells on leaves and stems. Sporangia colourless, with a nutritive cell inside. Synchytrium anomalum

2a Swellings bearing yellow aecia => 3

2b Swellings and malformations, up to 1 cm long, on stems, petioles and leaf veins with fungus developing only black, normally 3-celled teliospores, with dusty sori. Triphragmiopsis isopyri

3a Aecia on Leptopyrum fumarioides:

a Aecia golden-yellow, usually on distinct bulges on underside of veins, midrib or stalk of leaves. Puccinia actaeae-elymi

b Galls similar. Aeciospores narrow fine-warty. Outer wall of peridium 6–7 μm thick, transversely striate; inner wall coarse warty, 2–3 μm thick. Fungus alternating to wheat and related grasses. Puccinia recondita

3b Thickened bulges on the leaf axis and leaf blade. Puccinia milii-effusi

1a On above-ground parts => 2

1b Roots with nodular galls on Iris sp., up to 1 mm long or slightly larger. Iris spp.: Meloidogyne hapla

2a Leaves curled close to the ground, with slight irregular, spongy, pale green swellings. Iris sp., cultivated. Ditylenchus dipsaci

2b Fruit ± irregularly swollen, stunted and curved. Usually containing several white larvae. I. aphylla, foetidissima, x germanica, pseudacorus, sibirica and some cultivated forms: Mononychus punctumalbum

1a Leaves rolled inwards and ± curled. H. aureus, niger: Aphis fabae

1b On roots and stems => 2

2a Galls only on roots, primarily on adventitious roots; caused by eelworms => 4

2b Galls on main roots, sometimes encroaching onto stem base or only on stems => 3

3a Many proliferations, 1–3 mm long, rotund or irregularly shaped, which develop from side-, or higher located adventitious roots. H. niger: Synchytrium endobioticum

3b Young plants stunted; the basal stem parts and leaves, occasionally also the veins of leaves inserted there are ± sponge-like swollen H. aureus, niger: Ditylenchus dipsaci

4a Roots, especially side roots, with ± distinctly separated, nodular or spindle-shaped swellings with many side roots. H. aureus, niger: Meloidogyne hapla

4b Roots with slightly protruding, elongated, irregular tuberculate swellings; the parts situated beyond infestation usually disfigured. The developing ♀ ruptures the root rind with its body, producing the at first white, then yellow, eventually brown cysts attached to the outside of the gall body. H. aureus, niger: Globodera rostochiensis

1a Leaf blade curled and distorted => 2

1b Leaves with multicellular warts, depressed at the tip ± golden-yellow, later on browned, hardly 1 mm long. Often many on leaf underside, also coalescing into long ridges or crusts, also on petioles and tillers. Synchytrium aureum

2a Weak wrinkling or curling of leaf blade caused by aphids on underside. Aulacorthum solani

2b Leaf blade strongly deflected downwards, curled and dark-green close to the froth-covered nymph. Philaenus spumarius

2c More or less conspicuous, sometimes distorted locally bulge-like swellings on stems or slight archings on leaves, with loosely arranged aecia and spermogonia. Uromyces lineolatus

1a Weak swellings, several per leaf, small, distinguished by their lighter to red-brown colouration at infestation sites. Tissue containing spores. Heterodoassansia hottoniae

1a Brown, pad-shaped swollen telia, rotund on leaf underside, sometimes slightly countersunk on upper side, oblong-oval on axial parts, often resulting in distortions. Puccinia arenariae

1a On green plant parts => 2

1b On root collar, a one-sided rotund one-chambered swelling, up to 5 mm long. Containing a single white larva. H. alpina: cf. Ceutorhynchus assimilis

2a On leaves or stems => 3

2b lowers greened. H. alpina: Aceria drabae

3a More or less spindle-shaped galls on shoot axis => 4

3b Wart-shaped, multi-cellular, often variously coalesced galls on stems and flowers. H. alpina: Synchytrium infestans

3c Occasional infestation. H. petraea: Peronospora hornungiae

4a Vegetative part of stem spindle-shaped swollen. H. alpina: Unidentified snout beetle

4b Stem predominately swollen over variable length in inflorescence region and bearing white, later on vitreous, dusting of sori. H. alpina & subsp. auerswaldii, petraea: Albugo candida

4b Stem and also axis of inflorescence usually with expanded, conspicuous, often distorted swellings, soon covered with a down of branched conidiophores. Flowers of diseased inflorescences severely stunted. Leaves of axillary shoots if infected early, ± spoon-like arched, thickened, brittle, pale green; with a dense down of conidiophores on underside. H. alpina & subsp. auerswaldii, petraea: Hyaloperonospora parasitica

1a Malformations on shoot axis or leaves => 2

1b Malformations of capsules or exceptionally on stems, containing black-violet spores; seed capsule not- or slightly disfigured; ovaries temporarily swollen, soon transformed into a black-violet spore mass. Microbotryum holostei

2a Malformations at the surface, with fruiting bodies of fungi => 3

2b Shoot axis thickened because of short- to oblong-oval swellings; a rimmed depression containing the causer. Planchonia arabidis

3a Brown, pad-shaped swollen telia; rotund on leaf underside, sometimes slightly countersunk on upper side, oblong-oval on axial parts, often resulting in distortions. Puccinia arenariae

3b More strongly infected plants are occasionally ± stunted and excessively leafy. Weaker systemic infestation results in development acceleration, associated with etiolation. On leaf underside of similarly disfigured shoots whitish-grey down of conidiophores develop. Peronospora holostei

1a On flowers or leaves => 2

1b Roots with nodular- to spindle-shaped swellings of a few mm long. Meloidogyne hapla

2a Flower buds slightly swollen, not opening. Containing several ivory-coloured jumping larvae. Contarinia convallariae and/or C. polygonati

2b Leaf blade with many small galls, about 5–7 mm long, up to 4 mm broad, which only protrude when occupied. After departure of the larvae the at first pale green infestation sites show conspicuous green-margined spots on prematurely yellowing leaf blades. Unidentified gall midge

2c Aphids on underside of leaves. The leaves develop large yellow spots and become desiccated. Aulacorthum speyeri

1a On above-ground parts => 3

1b On roots or on root collar => 2

2a Main- or side roots with conspicuous, spindle-shaped to acuminated, cylindrical, succulent, compact swellings. Plasmodiophora brassicae

2b Up to 5 mm long, ± globular, one-chambered swelling on root collar. Containing a single larva. Ceutorhynchus assimilis

3a Malformation with white felt-like down of branched conidiophores on surface. Diseased leaf blade parts yellow-green, ± slightly bulging; completely infected leaves conspicuously deflected, spoon-like; leaf blade ± reduced and thickened. Stem occasionally stunted in the area developing the inflorescence, curved in case of one-sided infestation. Peronospora conringiae

3b At first closed glossy, porcelain-like, later on rupturing and with mealy dusting, rotund to oblong-oval pads. Leaf blades with ± many, locally rounded swellings on underside. Leaves, often stunted shoots and young fruits with conspicuous, ± expanded, often curved bulges. Many parts of more severely diseased flowers, especially calyx and ovaries, conspicuously enlarged and distorted. Albugo candida

1a Bulging galls, bearing fungal sori on vegetative plant parts => 2

1b Centre of (partial) umbel stalk swollen, globular to club-shaped. Gall wall rigid, covered inside with mycelium. Containing a red larva. Lasioptera carophila

2a Yellowish to brownish, ± distinct swellings on leaf veins; stronger, sometimes distorted bulges on leaf midrib and -stalk, also on young stems; pads bearing densely positioned telia. Puccinia tumida

2b Less conspicuous, bulging yellowish swellings on leaf axis bearing aecia.
Puccinia bistortae

1a Distinctly protruding smaller or up to about 20 mm long, ± distorted coalesced bulging swellings, bearing blackish, 3-celled, loosely long-spined telia. Nyssopsora echinata

1b Similar, usually less protruding bulges on leaf midrib, bearing, however, spermogonia and aecia. Puccinia altensis

1a Galls on vegetative plant parts => 2

1b Flowers stunted, not opening, transformed into ± globular galls. Containing several orange larvae. Unidentified gall midge

2a Leaves strongly curled or with additional pubescence => 3

2b Many spots on both sides of leaf, up to 1 mm across, rotund to angular, usually slightly swollen dark-violet; on petiole developing sori appear as oblong-oval bulges. Nutritive cells distinctly enlarged, with solitary or several (2–4) resting spores. Physoderma comari

2c Leaves are hardly disfigured, but a slight change of colour is discernable.
Bactericera acutipennis

3a Leaves at infestation sites, mainly on underside of leaf, densely silk-like pubescent; grey on corresponding upper side, almost brownish on underside. Phyllocoptes roivaineni

3b Leaf midrib at infestation deflected, severely stunted. Leaflets clustered, nest-like bent downwards, locally strongly crumpled and dark green. Philaenus spumarius

1a Galls on parts above ground => 2

1b Roots with many elongate-cylindrical or also fork-shaped to coralloid branched nodules. Colutea spp.: Rhizobium leguminosarum

2a Younger, already woody twigs irregularly swollen on one or all sides, with several rimmed depressions, containing a broad pear-shaped, white scale of a scale insect. Colutea spp.: Chionaspis salicis

2b Both halves of a leaflet folded upwards and slightly hypertrophied. Containing several flesh-coloured larvae. C. arborescens: Dasineura sp.

1a Linear, 1–3 mm broad, up to 10 (20) mm long, spindle-shaped tapering bulges of the veins predominantly the terminal, but also other above-ground and subterranean leaf parts; at first closed, lead-grey translucent; later on irregularly splitting open, with black-brown dusting of spore balls. Often many per leaf, sometimes coalescing. Colchicum spp.: Urocystis colchici

1b Above-ground parts with local, pale-green, spongy swellings; containing many eelworms inside. C. autumnale: Ditylenchus dipsaci

1a Leaf blade with groove-like depressions, warts or flat pocks => 2

1b Small, rotund, often circularly arranged, pale brown sori on not- or sometimes weakly swollen, discoloured leaf spots. C. alternifolium, oppositifolium: Puccinia chrysosplenii

1c Leaves yellowish-green, larger than normal with longer petioles; often umbrella-like with downwardly turned margins. C. alternifolium, oppositifolium: Peronospora chrysosplenii

2a Leaf blade with groove-like depressions. C. alternifolium: Unidentified psyllid

2b Almost circular spots, 2–6 mm long, whitish, later on dirty yellow brown, especially visible on leaf underside, appearing exceptionally weakly thickened. Tissue contains spores, rarely tender conidia at surface. C. alternifolium, oppositifolium, tetrandrum: Entyloma chrysosplenii

2c Less than a mm wide, brown, semiglobular warts, mainly on the lower leaves. C. alternifolium, oppositifolium: Synchytrium chrysosplenii

1a On parts above ground => 2

1b Roots with spindle-shaped to nodular swellings. Meloidogyne hapla

2a Leaf blades weakly wrinkled, margins slightly bent. Acyrthosiphon chelidonii

2b Weakly wrinkled and ± discoloured leaves caused by aphids. Aphis fabae

2b Wrinkled leaves. Malformations caused by froth-covered nymphs of Philaenus spumarius

2b Flowers distinctly swollen, unopened; many yellow, non-jumping larvae inside. Jaapiella chelidonii

2b Pods irregularly swollen. Containing several yellowish, non-jumping larvae.
Unidentified gall midge

1a Malformations on leaves and shoots, caused by fungi => 2

1b Axial parts with rimmed depressions; causers under scales up to about 2.5 (3) mm long. Chionaspis salicis

2a Leaves with slightly swollen, sometimes reddened spots, covered with white spores when mature. Exobasidium cassandrae

2b Expanded part of terminal shoot with discoloured and ± deflected leaves, which are smaller or larger and weaker than the normal ones. Eventually with white sori on underside. Exobasidium myrtilli

1a Roots with nodular swellings. Meloidogyne hapla

1b Several twigs constricted, above the infection with expanded, strong swelling of the axis, and exudation of resin. Pestalotiopsis funerea

1c Pycnidia occur on dead twigs; whether the fungus is the cause of death is probable, but not certain. Pestalotiopsis monochaetioides

1d eveloping cones are slightly discoloured and distorted. Inside, seeds are distorted and concave; in each hollow lies a pale yellow, later orange larva, which pupates in a white cocoon in early spring; a cone may contain more than 20 larvae. Cupressatia siskiyou

1a Capitula short stalked, bloated apically and usually spirally rolled below the flower. C. leucantha: Diceratura roseofasciana

= The gall midge Cephalaromyia capituli causes galls in flower heads of C. microcephala

1a Malformation of vegetative parts => 2

1b Flowers double, leaves disfigured. C. calcitrapa, macrosiphon, ruber:
Unidentified gall mite

2a Malformations caused by animals => 3

2b Upper side of the leaf with pale, eventually brown, spots. Underside with a greyish white down of erect conidiophores that are branching several times apically, each branch ending in a ± globular conidium. C. ruber: Peronospora centranthi

3a Axial parts of flowering and vegetative shoots ± stunted at tip; the variously disfigured organs clustered. Flower buds mostly stunted; leaves ± reduced, deflected and curled. Containing black aphids. C. calcitrapa, ruber: Aphis fabae

3b Leaves as well as bracts with pale green or reddened, ± fleshy thickened upward rolls of margin; smaller leaves completely disfigured. Infected flowers swollen, their parts variously disfigured and greened. C. angustifolius, calcitrapae, ruber: Trioza centranthi

1a Leaves on underside with many pearl-like small warts, hardly 1 mm long. C. pulchellum: Synchytrium globosum

1b Dull white spots, pustules, even crusts on underside of leaves, largely consisting of a mass of conidia. C. spicatum: Pustula centaurii

1c Plant ± disfigured; flowers greened. C. erythraea: Inducer unknown – ? gall mite

= Galls on Centaurium have been attributed to either the snout beetle Smicronyx reichi or S. funebris

1a Malformations of leaves => 2

1b Buds swollen on young twigs, about 8 mm long and 3–4 mm broad. C. australis: Aceria bezzii

2a Galls caused by aphids => 3

2b Galls caused by mites. Pale green, irregular and coalescing protrusions on upper side of leaf; corresponding depression on underside lined with whitish, 1-celled, simple, acuminate, thick-walled hairs with swollen base. The infected areas are twice as thick as the healthy ones. C. australis & subsp. caucasica: Reckella celtis

2c Galls caused by gall midges. Conspicuous blister gall on both sides of leaf; the blister is covered with short white hairs is on the underside, a concave depression covered with dense white fibers on the upper side. C. australis subsp. caucasica: Celticecis caucasicae

3a Pea-size protrusions on upper side with abnormally pubescent, bosselated surface. Often the complete leaf blade is covered with these galls; infected parts are fleshy and thickened. If several terminal leaves are infected, the twig is thickened and the leaves clustered. C. australis: Pemphigus sp.

3b Terminal leaves discoloured and curled. C. australis: Unidentified aphid

3b Irregular, discoloured protrusions on upper side leaf blade. C. crenata: Unidentified aphid

1a Malformations on parts above ground => 2

1b Considerable, ± rotund, broadly attached cancers close to the root collar. C. sativa: Agrobacterium tumefaciens

= Cancers observed on stems of young trees might, according to older references, be attributed to Diplodina castaneae

2a Galls caused by animals => 4

2b Stems with local, ± expanded swellings caused by mistletoes => 3

3a Evergreen mistletoe on spindle-shaped swelling. C. sativa: Viscum album

3b Deciduous mistletoe on slightly thickened branches, “woody roses”. C. sativa: Loranthus europaeus

4a Galls on young twigs, on leaf petioles or on the midrib of the leaves, unilocular or multilocular, 5–20 mm in diameter, green or rose-coloured, often including portions of developing leaves, stems and petioles. The gall dries, becomes wood-like, and remains attached to the tree for up to two years. C. crenata, dentata, mollissima, pumila, sativa, seguinii: Dryocosmus kuriphilus

4b Rotund pustule, about 1 mm across, slightly protruding on both leaf surfaces. Pustule paler than surrounding leaf blade. C. sativa: Unidentified gall midge

4c Bark of the two-year old and perennial twigs, usually on the underside with expanded, 2–3 mm thick, later with longitudinal fissures bursting proliferations of the cambium. C. sativa: Lachnus roboris

1a On above-ground parts => 2

1b Galls on roots, up to 7 cm deep in the ground, unilocular, sometimes more of them aggregated in groups, forming a root swelling. Carthamus sp.: Phanacis carthami

= Phanacis kiefferi induces galls on roots of C. lanatus.

2a On vegetative parts => 3

2b Capitula swollen, inhabited by tephritid larvae. C. tinctorius: Acanthiophilus helianthi

2c oluminous malformations, inhabited by tephritid larvae. C. lanatus, tinctorius: Unidentified tephritid, cf Urophora solstitialis

2d Capitula slightly swollen and disfigured, contain beetle larva. C. tinctorius: Larinus carinirostris

2e Gall in the involucral bracts, 1‒3 mm large. The wall is smooth, thick and very hard. C. lanatus: Isocolus carthami

3a Stems of young plants swollen at ground level, covered with pycnidia and brown areas of uredinia; developing malformed adventitious roots. C. glaucus, lanatus, oxyacantha, tenuis, tinctorius: Puccinia carthami

3b Leaf blade with round, compact cushions, weakly bulged on the lower side, sometimes weakly countersunk on the upper side. On the nerves round- to oval, usually slightly more swollen; at first yellow, later bearing 2-celled brown telia. C. lanatus, tinctorius: Puccinia verruca

3b Leaves on the underside with a dense white fungal down of erect conidiophores that apically bear a few short branches, each one ending in a conidium. C. tinctorius: Plasmopara carthami

1a On parts above ground => 2

1b Roots with laterally or terminally inserted branched nodules, oval, cylindrical or terminally fork-like, finger-shaped to coralloid. Rhizobium leguminosarum

2a Minor malformations of leaves. – Unidentified aphid

2b Main stems with ± spindle- or club-shaped swellings bearing mistletoe. Viscum album

= The gall mite Aceria arceosae, hidden in leaf axils, causes withering of buds.

= The mildew Erysiphe palczewskii has been reported from pea shrub

= The rare gall midge Dasineura sibirica may cause a pest

1a Malformations ± witches’ broom-like => 2

1b Leaves clustered at shoot tip, imbricated covered, transformed into a bud-like, egg-shaped gall. Inducer unknown

2a Shoots may bear witches’ broom-like malformations. Many very small (0.1‒0.2 mm) orange uredinia on underside of leaves, which soon fall. Thekopsora fischeri

2b Thin twigs abnormal, twig slightly inflated at insertion. Mytilaspis pomorum

2c Plant with small witches’ broom-like malformations of shoot; leaves clustered, reduced, often ± abnormally pubescent, usually pale-green or reddish discoloured. Aceria exigua

= The rust fungus Thekopsora ericae causes witches’ brooms. Uredinia on underside of leaf, 0.1‒0.2 mm across

1a On above-ground parts => 2

1b Roots with nodule-shaped swellings. Meloidogyne hapla

2a Leaf blades, veins, petioles, also stems of young plants with flat sori, on axial parts sometimes slightly swollen, occasionally bent. Uromyces junci

2b Leaf blade usually curved downwards obliquely over the top and margins ± nest- or roll-like. On the central part of the dark green area, strongly curled underside and with froth-covered nymph. Philaenus spumarius

1a Malformations of vegetative parts, mainly leaves => 2

1b Centre of umbel or stalk of umbel ± swollen, club-shaped. Inner wall covered with mycelium. Containing a single red larva. B. ferulaceum: Lasioptera carophila

2a Axis of leaves, also young stems, with expanded, sometimes severely distorted, ± yellowish swellings, bearing yellowish spermogonia and aecia. B. alpinum & subsp. corydalinum, atlanticum, bulbocastanum, cylindrium, ferulaceum, pachypodium: Puccinia bulbocastani

2b Leaf sheaths inflated, ± discoloured. B. bulbocastanum: Hyadaphis foeniculi

1a Malformations of vegetative parts => 2

1b Aborted flower buds contain several midge larvae. Asphondylia buddleia

2a Smaller roots with nodular swellings. Meloidogyne hapla

2b eaf blade over tip and margins usually loosely and obliquely rolled downwards; curled close to the froth-covered nymph. Philaenus spumarius

1a Leaf blade with rotund yellowish swelling, more oblong-oval to spindle-shaped close to venation, protruding on underside, bearing aecia on underside, spermogonia on upper side. Puccinia recondita

1b Leaf blades curved downwards over margin, curled. Bearing colonies of black aphids on underside. Aphis fabae

1a On leaves => 2

1b Shoot tips or lateral buds disfigured, leaves ± converging, discoloured, rolled upwards and inwards, also unopened and ± bud-like. Containing several white (yellow), jumping larvae. Contarinia ballotae

2a Upper leaves, including shortened petioles, swollen and succulent at base, sometimes additionally pubescent. Containing yellowish-white larvae. Unidentified gall midge

2b Leaf blades at shoot tips or in inflorescences slightly bent in at margin, ± arched and slightly curled. Brachycaudus ballotae

1a On parts above ground => 2

1b Roots with small, nodular or spindle-shaped swellings. Meloidogyne hapla

1c Eelworm, making cysts on root surface. Heterodera humuli

2a Petioles and midribs, partially shortened, spongy, thickened; leaf blades stunted and distorted. Stem mainly at base, in case of later infestation also locally swollen and pale green higher up. Gall tissue brittle. Axial parts above bent or twisted galls ± severely stunted. In cases of early infestation additional side shoots develop. Ditylenchus dipsaci

2b Inflorescences, especially the female ones, disfigured and sometimes greened; development of fruits stunted. Phorodon cannabis

1a Leaves with bulging swellings on the surface of which develop ± yellowish or brown sori => 2

1b Bulges on leaves and stems, initially lead-grey translucent, later on rupturing and releasing a dusting of black spores. C. coriandrifolium: Urocystis callianthemi

2a Slightly thickened, above violet, below yellowish, brownish margined spots bearing dense aecia and spermogonia. Sori on midrib and petiole bulging. C. angustifolium, coriandrifolium: Puccinia sardonensis

2b ulges yellowish to brown-red, remaining closed for a long time, compact, often yellow- or red-margined; with dark telia. C. coriandrifolium:
Puccinia callianthemi and/or P. kochiana

1a Galls contain midge larva inside => 2

1b Swelling of stem bearing rimmed depressions which contain causer. C. spinosa: Planchonia arabidis

1c Swelling of stem containing beetle larva. C. spinosa: Protopirapion kraatzii

2a Oblong to egg-shaped bud gall, green, succulent, covered with silk hairs. C. infesta subsp. intermedia, spinosa, villosa: Asphondylia calycotomae

2b Pods disfigured and shortened, up to 20 mm long, with a single spherical thick-walled swelling enclosing a large larval chamber. C. infesta subsp. intermedia, spinosa, villosa: Asphondylia calycotomae

1a On parts above ground => 3

1b On root collar or on roots => 2

2a Root collar with rotund galls, up to about 8 mm long, succulent, one-sided, one-chambered. Containing a single larva. Ceutorhynchus assimilis

2b Roots with conspicuous, spindle-shaped to cylindrical swellings, 3–12 mm long succulent, compact. Plasmodiophora brassicae

3a Midrib of leaves or young stems with 12–20 mm long spindle-shaped swellings. Containing a single larva. Ceutorhynchus chalybaeus

3b According to literature on this host also Brevicoryne brassicae as well as Albugo candida

1a On above-ground parts => 2

1b Roots with many small, nodule-shaped swellings. C. officinalis: Meloidogyne hapla

2a On leaves => 3

2b Enlarged leaves and stems, with transformation of flowers into scaly structures on peduncles up to 20 mm long. Calendula sp.: Unidentified aphid

= The capitula of Calendula arvensis, maderensis are hardened by the tephritid fly Tephritis praecox.

3a Leaf blades of the larger leaves variously curved obliquely downwards or almost rolled; curled close to the dark green site of attack. One froth-covered nymph. Calendula spp.: Philaenus spumarius

3b Leaf blades often with many, rotund, up to 5 (7) mm wide, yellowish-white, later bright brownish spots, occasionally slightly curved over the surface. C. arvensis, officinalis, suffruticosa incl. subsp. fulgida: Entyloma calendulae

1a On parts above ground => 2

1b Side roots with nodular swellings, up to 3 mm long and 2 mm broad. B. scoparia: Meloidogyne hapla<

2a Malformation caused by animals => 3

2b Malformation caused by false mildews => 5

3a Shoot tip stunted => 4

3b Pod-shaped upwards folds on slightly thickened and discoloured, partially sickle-curved downwards curved halves of leaf blade. B. scoparia: Hayhurstia atriplicis

4a Gall consists of a rotund tuft of olive-coloured leaves, 10–15 mm across; leaves longer and more pubescent than normal ones, covered with abundant, long, whitish hairs. Leaves inserted on a shortened twig, succulent, one- or multi-chambered. Each chamber contains a single whitish larva. B. muricata: Stefaniola houardi

4b Terminal leaves and vegetative buds, which are transformed into small one-chambered galls, and inflorescence primordia, with long, dense pubescence; infected organs united into a tuft, about pea- to hazelnut-size, usually rotund, sometimes elongated. B. prostrata: Kochiomyia kochiae

5a Upper side of the leaf with lemon yellow spots. Underside with a brown down of erect conidiophores that apically are dichotomously branching several times, each branch ending in a conidium. B. prostrata: Peronospora kochiae-prostratae

5b Similar malformation, spots pale and down greyish purple. B. scoparia: Peronospora kochiae-scopariae

1a On parts above ground => 2

1b Woody swelling of root, 20 mm long, 15–18 mm thick. Mirificarma mulinella

2a On leaves => 3

2b Shoot tip ± unopened. Leaves folded, slightly thickened, sometimes erect, enclosing tuft-like severely disfigured leaf- or flower primordia. Cause unknown – ? gall midge

3a Young leaves with slightly swollen folds at base. Cause unknown – ? gall midge

3b Leaf blades rolled downwards at margin, there discoloured yellowish or reddish, externally ± abnormally pubescent. Aceria bartschiae

1a Leaves with only small, wart- or spindle-shaped galls caused by fungi => 2

1b Shoots shortened at tip. Leaves shortened and broadened, spoon-like, tuft-like clustered, abnormally haired. A. chamaejasme: Unidentified gall mite

2a Galls bulge-shaped, bearing spores at surface => 3

2b Galls cylindrical, less than 1 mm long, usually many on the underside of leaves. A. chamaejasme: Synchytrium aureum

3a Pad-shaped sori bearing black-brown spores on rosette leaves, also on inflorescence stalks and even bracts. A. chamaejasme: Puccinia volkartiana

3b Rotund to oblong, dark-brown sori on both leaf sides, also on flower peduncles of A. alpina, carnea, helvetica, lactea, obtusifolia, pubescens: Puccinia dubyi

1a Malformations on expanded parts of shoot or on leaves => 2

1b Stem with rimmed depressions with causer under a 2.5 (3) mm long scale.
Chionaspis salicis

2a Single or several leaves with localised malformations => 3

2b Complete shoots infected, ± etiolated or ± disfigured witches’ broom-like. Leaves partially larger, partially smaller than healthy ones; hardly thickened; sometimes pale-green, often conspicuously reddened. At maturity of fungus the underside with white down of basidia. Exobasidium myrtilli

3a eaf blade ± keel-shaped curved, hardly thickened. Conspicuously rolled downwards at margin, ± reddish discoloured. Cecidophyopsis ruebsaameni

3b Leaf blades with expanded, strongly swollen, usually conspicuously reddened swellings. Twigs hypertrophied, leaves disfigured and discoloured reddish to violet. Exobasidium karstenii

3c Twigs not thickened, but leaves broadened and thickened, reddish. Exobasidium sundstroemii

1a On above ground organs, sometimes encroaching onto upper part of main root => 2

1b Side roots with nodular or spindle-shaped swellings. Amaranthus spp.: Meloidogyne hapla

= The cyst-developing eelworm Heterodera schachtii has been recorded on several Amaranthus species

2a On stems or leaves => 3

2b Flowers of single panicles ± enlarged, thickened and reddened. Bracts cylindrically thickened, rolled, inflated, wrinkled. A. retroflexus: Inducer unknown; possibly galls with oospores of Wilsoniana bliti.

3a Shoot tips ± stunted. Leaves ± clustered, margins deflected, sometimes contacting; leaf blades arched upwards, ± curled and partially discoloured. Amaranthus spp.: Aphis fabae

3b Axial parts, sometimes also flower parts, variously swollen, also ± distorted. Inside tissue is a mycelium which develops oospores. Mature oospores dark brown-red to blackish translucent. Amaranthus spp.: Wilsoniana bliti

1a Malformations of complete shoots or extended systems of shoots => 2

1b Stem, mainly close to ground, with sometimes bent, bulging swellings, on their surface with scale insects in single to several rimmed depressions. T. bavarum, humifusum: Planchonia arabidis

1c Yellow, rough nodular swellings, 2–8 mm across, clustered on root collar. T. humifusum: Unidentified weevi

2a Shoots completely pervaded and ± disfigured by perennial mycelium of a rust fungus. Aecia, unopened longer than wide, often ± red-brown coloured, occurring on both sides of leaf, on stems, occasionally also on bracts and flowers => 3

2b Inflorescence usually largely disfigured; excessive branching and leafiness; phyllanthy. T. alpinum, divaricatum, humifusum, linophyllon: Aceria anthonoma

3a The three monoecious rust fungi occurring on Thesium cannot be distinguished according to their aecia. Uredina easily detached, their sori later on ± with dusting. Aecia often rare or almost absent => 4

3b Teliospores glabrous, on compact stalks; sori compact. Aecia often present. Thesium spp.: Puccinia thesii

4a Fungus mainly on T. alpinum and T. linophyllon: Puccinia mougeotii

4b On several other Thesium species, mainly on T. ebracteatum: Puccinia passerinii

1a Leaf blade with slight swellings, up to 3 mm, yellowish, which bear asci later on the underside. Taphrina lutescens

1b ip of frond distinctly shortened, spirally rolled upwards, with the crowded leaflets making a dense nest. With a white larva on the midrib. Chirosia betuleti

1a Aecia spaciously arranged, on underside of leaf blade on thickened, arched, rotund yellowish or brownish cushions or on oblong-oval, weak bulges on petioles and stems. Puccinia swertiae

1b Rotund-oval or flat spindle-shaped, one-chambered galls, up to 6 mm long; usually on petiole, also on leaf blade, on base of midrib as well as on stem base. Containing a single larva. Smicronyx swertiae

1a On parts above ground => 2

1b Roots usually with several to many nodular to spindle-shaped swellings, bearing several lateral roots. Meloidogyne hapla

2a In capitula or flowers => 4

2b On leaves => 3

3a Broad, many-celled warts, up to 1 mm high, pearl-like, yellowish-green. Usually many, solitary or variously coalesced later on into ± browned, flat ridges or crusts; after infestation on all green, not distinctly discoloured organs. Synchytrium succisae

3b Leaf blade with small grooves on underside. Mites free-living on underside of leaves, if strongly infected, conspicuously pale or brownish discoloured. Leipothrix succisae

4a Malformations caused by fungi => 5

4b Flowers compact, ± disfigured; unopened. Containing a whitish- to orange-yellow larva. Contarinia dipsacearum

5a Fungus develops on several flower parts or in ovary => 6

5b Fungus lives in externally unchanged flowers in originally shortened and bloated, soon completely aborted anthers; containing a whitish, to ochre coloured, later on dusty spore powder. Microbotryum succisae

5c The anthers are transformed into a purplish-brown powdery mass of spores.Microbotryum flosculorum

6a Diseased flowers sometimes strange-looking, ± discoloured. Several petals enlarged and ± disfigured. Generative parts greatly reduced. Loose down of branched conidiophores on emerging petals of usually completely diseased capitula. Peronospora violacea

6b Fungus develops in soon destroyed ovary, stigmas thickened and distorted; corolla unopened; anthers normal. Strongly infected capitula prematurely browned and dying. Covered with salmon-pink to orange slimy speckles when spores are mature. Gibberella fujikuroi

1a Galls caused by gall midges => 2

1b Malformations caused by fungi. Rotund, mainly protruding on underside, upperside ± depressed pads on leaf blades, or acuminate rotund- to oblong-oval aecia and spermogonia bearing bulges on leaf midrib, -stalk, stems and sporadically even on stalks of umbels and fruits. S. apiifolium, cordifolium, olusatrum, orphanidis, perfoliatum & subsp. rotundifolium: Puccinia smyrnii

2a Galls in umbellules and fruits, inside wall lined with mycelium. S. orphanidis, perfoliatum subsp. rotundifolium: Lasioptera carophila

2b Fruit conspicuously swollen, ± reddened, often protruding above the partial umbel. Containing a single orange-red larva. S. olusatrum: Kiefferia pericarpiicola

1a On stems or leaves => 2

1b Fruit disfigured into a ± globular swollen gall. Containing a single orange-red larva. Berula erecta: Kiefferia pericarpiicola

2a Wart-shaped or bulge-like galls caused by fungi => 3

2b Leaf midrib stunted and deflected. Leaflets ± clustered, ± curled and locally deep green. Berula erecta; Sium. latifolium, sisarum: Philaenus spumarius

3a Spores inside galls => 4

3b Veins on underside of leaf with weak, ± rotund-oval bulges; midrib and stalk with broad spindle-shaped, stronger protruding swellings, bearing yellowish spermogonia and aecia. Berula erecta; S. latifolium: Uromyces lineolatus

3c Leaves with discoloured spots. On the underside is a whitish fungal down, consisting of erect, terminally repeatedly branching conidiophores, each branchlet bearing a globular conidium. S. latifolium: Plasmopara sii

4a Galls elongate spindle-shaped, vitreous, pale green; often adjoining venation; depending on the plant part only a few to many mm long. On all green plant parts; sometimes even on calyx and fruits. Within the tissue close to vascular bundle are many, ± rotund, often 60–70 µm large perennial (‘dauer’) spores. Berula erecta; Sium latifolium: Protomyces macrosporus

4b Only a few mm long, wart-shaped, usually many, at first colourless-whitish, then dull brown galls, which cluster on leaf blade, -midrib, -stalk and stem may cause additional malformations. Inside nutritive cell several, about 20–35 x 15–30 µm large perennial (“dauer”) spores. Berula erecta; S. latifolium: Physoderma vagans

1a On parts above ground => 2

1b Roots with small nodular or spindle-shaped swellings. Meloidogyne hapla

2a Leaves broadened terminally on non-flowering shoots, ± arched or rolled, usually yellowish or reddish. Trioza velutina

2b Stem gall containing a single yellow midge larva. Dasineura sp.

2c Diseased young plants densely bushy. Internodes sometimes stunted, like adjacent reduced, pale-green leaves slightly thickened and lined by a down of branched conidiophores. Peronospora sherardiae

1a Malformations on inflorescences or florets => 3

1b Malformations on leaves, sometimes extending to inflorescence => 2

2a Leaf sheaths swollen; leaf blades variously disfigured. S. pumila: Rhopalosiphum padi

2b Diseased leaves remain rolled inwards, strongly thickened, brittle, at first pale, eventually fraying and releasing reddish-brown oospores. Inflorescence stunted, usually remaining in the leaves; peculiarly leaf-like and greened. S. adhaerens, italica, pumila, verticillata, viridis: Sclerospora graminicola

2c Leaves with long narrow stripes of smut. S. italica: Ustilago striiformis

3a Galls on ovaries caused by smut fungi => 4

3b Spikelets disfigured; sometimes ± greened and leaf-like. Glumes occasionally strongly elongated and rolled. Strong infestation results in bleaching. S. viridis, italica: Aceria tenuis

4a Ovaries swollen, soon filled with black-brown spore masses; spores glabrous, irregular rotund, 8–11 x 6–9 µm, dusty when mature. S. adhaerens, faberi, italica, parviflora, pumila, verticillata, viridis: Ustilago crameri

4b Ovaries strongly swollen. Diseased inflorescences often discoloured grey; appearing compact and thickened. Spores black, with spiny warts, globular to rotund-oval, usually 7–11 µm across. S. adhaerens, pumila, viridis: Macalpinomyces neglectus

4b Ovary hypertrophied by smut fungus. S. pumila: Sporisorium magnusianum

1a On parts above ground => 2

1b Roots with small, spindle-shaped swellings, bearing some side roots. S. annuus: Meloidogyne hapla

2a Malformations bearing fruiting bodies of fungi => 4

2b Malformations caused by animals => 3

3a Many leaves mainly distorted at shoot tips, thickened, sometimes bent S-shaped or rectangular, ± discoloured and showing suction feeding marks. S. annuus: Taeniothrips atratus

3b Whole plant atrophied. Basal parts with ± distinct, pale-green, spongy, soon necrotic, swellings. S. annuus: Ditylenchus dipsaci

4a Developing more on leaves if plants are infected early. Diseased shoots developing prematurely, growing rigidly erect. Internodes elongated, lanky; leaves smaller, slightly thickened, paler and often more deflected than healthy ones. Infected organs soon covered by a down of branched conidiophores. S. annuus, perennis: Peronospora scleranthi

4b Leaves and stems with rotund to oval powdery sori, sometimes slightly swollen and distorted on young organs, pale to red-brown. S. perennis: Uromyces scleranthi

1a Galls on above-ground parts => 3

1b Galls on roots => 2

2a Swellings on all sides, slender, elongate spindle-shaped, many on markedly shortened lateral roots. S. sylvaticus: Meloidogyne hapla

2b wellings on root tips almost club-shaped. Many oblong-oval to lemon-shaped, yellowish spores inside. Isolepis fluitans: Entorrhiza raunkiaeriana

3a Swelling in stem, about 15 mm long, at junction of leaf blade and sheath, probably on stunted shoots; containing a white larva or pupa. Bolboschoenus maritimus: Eurina lurida

3b Uredinia on underside leaf, cinnamon brown, pulverulent. Telia on both sides, long covered by the epidermis, brownish black; teliospores one-celled on a persistent pedicel. Blysmus compressus; Bolboschoenus maritimus; Schoenoplectus lacustris: Uromyces lineolatus

3b Ovaries at first ± swollen, egg-shaped then destroyed and transformed into a smut grain up to 2 mm long, almost globular, compact, black inside. Trichophorum cespitosum incl. subsp. germanicum, pumilum: Anthracoidea scirpi

1a Galls localised or extending over leaves => 2

1b Development of flower head stunted, heads remaining closed, appearing ± globular turgid; soon filled with brown spore masses. Thecaphora trailii

1c Gall midge larvae in flower heads. Dasineura saussureae

2a Leaf blade with ± rotund pads bearing aecia, protruding on the underside, not or slightly swollen. Puccinia rupestris

2b Galls caused by animal parasite => 3

3a Malformations extensive, of various types => 4

3b Leaf blade with many small, pustule-like swellings. Aceria saussureae

4a Leaf blades or petioles with ± expanded, spongy, pale green, often rugose swellings. Ditylenchus dipsaci

4b Large parts of leaves curved downwards or rolled. Infected leaf blade parts ± crookedly curled and coloured dark green close to the froth-covered nymph. Philaenus spumarius

1a On parts above ground => 2

1b Roots with laterally inserted nodules, rotund to oblong-oval or terminally broadened and hand-shaped to coralloid forked, up to 10 or more mm long, occasionally clustered. Rhizobium leguminosarum

2a On leaves => 3

2b Branches with ± distinct spindle- or club-shaped swellings, bearing. Viscum album

3a Malformations of leaflet caused by aphids => 5

3b Malformations of leaf caused by other animal inducers => 4

4a Cartilaginous, yellowing downward rolls of leaflet margins. Containing several whitish midge larvae, often together with orange-yellow pupae. Obolodiplosis robiniae

4b Leaflets curled, ± bluish discoloured, ± rolled at margin. Aculops allotrichus

5a Leaflet rolled downwards, curled. Aphis craccivora

5b Similar malformations. Aphis fabae

1a On parts above ground => 2

1b Rotund, about pea-size, fleshy swellings on root collar. Containing a curved beetle larva. P. alliacea: Ceutorhynchus assimilis

2a Leaf blade buckled downwards, undulately curled, the margins bent downwards; locally deep green. P. alliacea, turkmena: Philaenus spumarius

2b Stalk of inflorescence stunted and ± bent. The only short stalked flower buds clustered; slightly swollen; unopened. Containing yellowish larvae. P. alliacea: Unidentified gall midge

1a On parts above ground => 4

1b On root collar or roots => 2

2a Conspicuous gall formation on root collar => 3

2b Roots with nodular swellings. Pelargonium spp.: Meloidogyne hapla

3a About walnut-sized proliferations, irregularly tuberculate on surface, at first succulent, whitish, then browned or blackened, ± globular. Pelargonium spp.: Agrobacterium tumefaciens

3b Clumpy accumulation of severely stunted shoots, swollen in all their parts. “Leafy gall”. Pelargonium spp.: Rhodococcus fascians

4a Leaf blades variously deflected, with conspicuous necrotic spotting and strong malformations. Pelargonium spp.: Aulacorthum solani

= The “Pelargonium aphid” occurring in greenhouses in central Europe, Acyrthosiphon malvae lives on P. grandiflorum, more rarely on P. peltatum, tricolor, zonale, and affects especially the terminal shoots, which are conspicuously crumpled. The aphid may transmit Pelargonium-Virus 1, which, by localised stunting, results in bulging and occasional rupturing of the leaf blades of the often severely distorted plants

= Cultivated “geraniums” (Pelargonium zonale and hybrids) are often affected by Puccinia pelargonii-zonalis with cinnamon uredinia at underside of leaf and teliospores when present formed in the uredinia

1a Malformations of vegetative plant parts => 2

1b Galls in swollen flower buds caused by various undescribed Dasineura spp.

2a Galls wart-like, or, bulge-shaped or rolls of leaf margin => 3

2b Shoot axis stunted; leaves ± curled, locally deep green, converging, deflected, almost nest-like. P. palustris: Philaenus spumarius

3a Wart- or ± spindle-shaped galls caused by fungi => 4

3b Leaf tips ± crookedly rolled downwards, often reddened, densely felt-like, inside, sparsely pubescent on outside. P. lapponica, palustris, sylvatica, verticillata: Aculops pedicularis

4a Less than 1 mm long, multicellular yellow warts on leaf blades, stalks and stems, sometimes coalescing and additionally disfiguring the organs. Pedicularis spp.: Synchytrium aureum

4b Yellow, often distinct, spindle-shaped bulges on petioles or stems; rotund on the leaf blade, with arched pads on underside bearing aecia; Spermogonia develop on upperside. P. mixta, palustris, resupinata, sceptrum-carolimum, sylvatica: Puccinia paludosa

1a On above ground organs => 2

1b Oval to cylindrical nodules, terminally sometimes hand-shaped or forked, coralloid. Oxytropis spp.: Rhizobium leguminosarum

2a On stems, leaf axis or shoot tips => 5

2b On leaflets => 3

3a Galls caused by animals => 4

3b Large parts of plants slightly disfigured and etiolated by a perennial mycelium. Aecia usually often many on the undersides of many leaves, distinguished by their pale colour. O. campestris & subspp. sordida + tyroliensis, jacquinii: Uromyces lapponicus

4a Halves of leaf blade folded together, slightly thickened. Containing one or two at first yellowish larvae. O. jacquinii – Unidentified gall midge

4b Halves of leaf blade folded upwards, pod-like, distinctly thickened. O. campestris: Unidentified gall midge

5a Whole plant stunted. Shoot tip and side shoots transformed into a mass of strongly felt-like pubescent leaflets. Shoot axis ± bent. Larvae pale yellow. O. pilosa: Unidentified gall midge

5b Shoot axis, petiole and midrib (rarely also midrib of a leaflet), with single or several, mainly one-sided, 2–5 mm long, tough, one-chambered, often yellowish swellings; occasionally coalescing on stem into multi-chambered galls. O. pilosa: ? gall midge, ? chalcid

1a On leaves => 2

1b Flower buds almost globularly swollen. Perigone enlarged. Flesh-coloured spore masses in ovaries, also at base of stamens. Usually many diseased buds, clustered in inflorescence. Microbotryum vinosum

2a Leaf blade curved and distorted downwards at margin. Locally strongly curled, deep green. Philaenus spumarius

2b Leaf blade ± uniformly strongly curled and deflected. Aphis fabae

1a On above-ground parts => 2

1b Roots with nodular swellings. Ornithogalum spp.: Meloidogyne hapla

1c Cotyledon thickened and often ± crisp. O. candicans: Ditylenchus dipsaci

2a Expanded bulges on green parts => 3

2b Galls just visible to the naked eye, developing from epidermis cells; simple hemispherical, dirty white, brown margined; single or in groups, resulting in curling of the leaf. O. umbellatum: Synchytrium niesslii

3a Bulges compact, slightly protruding, yellow or yellow-margined, soon covered with dark-brown sori containing 2-celled teliospores. Species only distinguishable microscopically => 5

3b Bulges ± swollen, bladder-like, at first vitreous, lead-grey translucent, then breaking open and producing dusting of black smut spores. Species only distinguishable microscopically => 4

4a Spores single. O. boucheanum, narbonense, umbellatum: Vankya ornithogali

4b Spores united in larger balls, with (1) 2–3 or more, enveloped by a layer of sterile auxiliary cells. Ornithogalum spp.: Urocystis ornithogali

5a Teliospores glabrous, 50–70 x 25–35 µm. Ornithogalum spp.: Puccinia liliacearum

5b Surface of teliospores covered with coarse warts; on average about 24‒35 x 49–52 µm. Ornithogalum spp.: Puccinia lojkaiana

1a Large globular leaf bud rosette at vegetative tip, about 15 mm across, composed of many little disfigured leaves. Gall midge larvae develop among leaves, each folded leaf containing a single larva. O. frutescens: Janetiella onosmae

1a Receptacle thickened and hardened, with several oblong oval chambers vertical to surface, each containing a single maggot. O. acanthium, cynarocephalum: Tephritis postica

1b Similar malformations. O. acanthium: Urophora mauritanica

1c Larger parts of rosette leaves strongly curved downwards and curled; discoloured dark green close to the froth-covered nymph O. acanthium: Philaenus spumarius

1a On parts above ground => 2

1b Egg-shaped or cylindrical, often apically forked nodules. Ononis spp.: Rhizobium leguminosarum

2a On vegetative organs => 3

2b Pod swollen; inner wall with mycelium. Containing single yellow larva. O. minutissima, natrix & subsp. hispanica, spinosa & subspp. hircina + procurrens, talaverae, tridentate: Asphondylia ononidis

2c Flowers unopened, containing a single midge larva. O. repens: Undescribed gall midge

3a On expanded parts of shoots or lateral buds => 4

3b Leaflets folded upwards, pod-like, weakly thickened, swollen belly-like. O. minutissima, pusilla, spinosa subsp. hircina: Dasineura columnae

4a Locally restricted galls => 5

4b Main- and side shoots terminally with dense bushy clustering of small, mainly stunted, abnormally pubescent leaflets, witches’ broom-like. Stipules enlarged; flowers aborted. O. arvensis, natrix, spinosa & subsp. hircina +procurrens, tridentata: Aceria ononidis

5a Terminal internodes of shoot axis shortened, leaves ± disfigured, at top in bushy clusters. Containing yellow larvae. . O. natrix, repens, spinose & subsp. procurrens: Contarinia ononidis

5b A bud-like, egg-shaped, weak fleshy gall in leaf axils or terminally on side shoots, emerging from enlarged, folded stipules; leaflets atrophied. Inner wall with mycelium. Containing a yellow larva. O. minutissima, natrix & subsp. hispanica, spinosa & subspp. hircina + procurrens, talaverae, tridentate: Asphondylia ononidis

1a On stems and leaves => 2

1b Centre of umbel or stalk of umbel ± swollen, club-shaped. Inner wall covered with mycelium. Containing a red larva. O. aquatica: Lasioptera carophila

1c Bladder-like fruit galls on O. pimpinelloides: Kiefferia pericarpiicola

2a Galls conspicuous, oval or elongate spindle-shaped => 3

2b Galls less than 1 mm across, multicellular, wart-shaped, yellow translucent; usually many on lower stem parts, petioles, leaf veins and -blades. O. aquatica:
Synchytrium aureum

3a Bulges yellowish, soon bearing aecia. O. aquatica, crocata, fistulosa, globulosa, lachenalii: Uromyces lineolatus

3b Vitreous, yellow-green, unopened bulges of various size on all green parts. O. crocata, fistulosa: Protomyces macrosporus

3c Leaves, especially young ones, blistered and with white down covering underside. O. crocata: Plasmopara baudysii

1a Stem bulging, swollen, also bent, with oval, rimmed, shallow depressions, which contain inducer. Planchonia arabidis

1b Yellowish, often conspicuous bulges on ± curved stems, petioles, leaves and cotyledons bearing aecia and spermogonia. Puccinia actaeae-elymi

1c In similar aecia in Nigella species develops the usually weakly cecidogenic. Puccinia actaeae-agropyri

1a On roots or root collar => 2

1b ale green, spongy, bladder- or bulging expanded swellings, 5–20 mm long or more; on young plants mainly at stem base, on older ones higher on stem. Ditylenchus dipsaci

1c Stunting of growing points, curling of leaves. Myzus persicae subsp. nicotianae

2a oots with spindle- shaped or nodular swellings. Nicotiana spp.: Meloidogyne hapla

2b Conspicuous cancer-like malformations of various size, mainly on root collar, but also on higher situated stem parts. Nicotiana spp.: Agrobacterium tumefaciens

2c On the root collar, especially of N. glutinosa, less on N. tabacum occur the leafy galls Rhodococcus fascians

1a On parts above ground => 3

1b On roots or on root collar => 2

2a Long cylindrical- to short barrel-shaped swellings on main- and adventitious roots. Plasmodiophora brassicae

2b Root collar with ± globular swellings; containing a curved beetle larva.
Ceutorhynchus assimilis

3a Malformations caused by fungi => 4

3b talks of flowers or young inflorescences stunted, often ± bent, parts ± disfigured. Brevicoryne brassicae

4a On the leaf blades rotund, on axial parts of leaves, on stems and inflorescences spindle-shaped, at first lacquered glossy, then with white dusting, sometimes curved bulges. Albugo candida

4b Diseased leaves locally swollen or if totally infected ± spoon-like, bent downwards. Stem often infected over large expansion, slightly thickened and variously distorted. On leaf underside and stems expanded white down of branched conidiophores develop. Hyaloperonospora nesliae

1a Malformations on leaves => 3

1b Galls on shoot axis => 3

2a Young shoots with small bulge-like, oval swellings, which contain the causer in a central depression. Epidiaspis leperii

2b Older shoot stems with spindle- to club-shaped swellings. Viscum album

3a Galls caused by aphids => 5

3b Galls induced by other causes, locally delimited => 4

4a Underside of leaf blades with felt-like pubescence. Eriophyes pyri

4b Yellowish or brownish bulges on the underside of leaf blades, rotund-oval, elongate spindle-shaped on venation, developing fibrous aecia that tear open. Gymnosporangium confusum

5a Extensive malformations caused by aphids => 6

5b Leaf margin rolled downwards. Aphid covered with white woolly wax. Prociphilus pini

6a Leaves on stunted shoot tips hardly discoloured, strongly rolled and curled; aphid 2 mm long, leaf- to dark-green with dark brown-black siphunculi. Aphis pomi

6b Similar malformations; aphid yellowish-green, with segmental dark-green stripes on back and pale siphunculi, only dark at tip. Rhopalosiphum oxyacanthae

1a On parts above ground => 2

1b Roots with ± expanded, spindle-shaped to cylindrical, compact swellings. M. longipetala subsp. bicornis, tricuspidata: Plasmodiophora brassicae

2a Galls of irregular shape are expanded to involve several organs or larger parts of single organs => 3

2b White bulges, up to about 10 mm long, at first glossy, porcelain-like, later on dusty on axial parts of leaves or on stems. M. fruticulosa, incana: Albugo candida

3a Malformations caused by animals => 4

3b Stems or leaf axis diseased and swollen over different lengths, sometimes curved and soon covered by a down of white conidiophores. M. incana: Peronospora matthiolae

4a One-sided infected axis ± curved, leaves clustered, deflected over their tip and slightly curled. M. incana: Philaenus spumarius

4b Locally restricted or extensive on young leaves, ± discoloured folds and curls of the leaf blade. M. incana: Brevicoryne brassicae

1a On parts above ground => 2

1b Conspicuous, spindle-shaped to cylindrical, fleshy swellings on roots.
Plasmodiophora brassicae

2a Upperside of the leaf with purple, ultimately brown spots. Underside with a greyish-white fungal down consisting of erect conidiophores; towards the tip these are several times branching at right angles. Conidia egg-shaped. Hyaloperonospora lobulariae

2b Usually all flowers of a single or several inflorescences greened. Aceria drabae

1a On parts above ground => 3

1b On root collar or on roots => 2

2a Roots with slender- to broad spindle-shaped galls, a few mm long.
Meloidogyne hapla

2b Root collar or also basal axial parts with conspicuous proliferations, irregularly fissured at surface, almost walnut-size. Agrobacterium tumefaciens

3a Malformations mainly on leaf blades => 4

3b Stem shortened, spongy, thickened and ± distorted; the stalks and basal vein parts at infestation site clustered, leaves bloated, the leaf blades variously curved. Flowers, if present close to infestation, disfigured and ± greened, stalks ± strongly thickened. Ditylenchus dipsaci

4a Curling, arching and upwards development of leaf blade caused by aphids; or malformations of flowers => 5

4b Leaf blade with pustule-shaped galls which are soon surrounded by an expanded area of dead tissue. Cause unknown – ? gall midge

5a Malformations on plants cultivated in greenhouse. Aulacorthum solani and/or Macrosiphum euphorbiae

5b Flowers on variously stunted stems more densely arranged, greened; corolla leaves usually stunted in development. Stamens and ovaries sometimes leafy. Virus disease

1a On green plant parts => 2

1b On root collar, a one-sided rotund one-chambered swelling, up to 5 mm long. Containing a single white larva. Hornungia alpina: Ceutorhynchus assimilis

2a On leaves or stems => 3

2b Flowers greened. Hornungia alpina: Aceria drabae

3a More or less spindle-shaped galls on shoot axis => 4

3b Wart-shaped, multi-cellular, often variously coalesced galls on stems and flowers. Pritzelago alpina: Synchytrium infestans

3c Occasional infestation. Hornungia petraea: Peronospora hornungiae

4a Vegetative part of stem spindle-shaped swollen. Hornungia alpina:
Unidentified snout beetle

4b Stem predominately swollen over variable length in inflorescence region and bearing white, later on vitreous, dusting of sori. Hornungia alpina, petraea; Hymenolobus procumbens; Pritzelago alpina incl. subp. auerswaldii: Albugo candida

4c Stem and also axis of inflorescence usually with expanded, conspicuous, often distorted swellings, soon covered with a down of branched conidiophores. Flowers of diseased inflorescences severely stunted. Leaves of axillary shoots if infected early, ± spoon-like arched, thickened, brittle, pale green; with a dense down of conidiophores on underside. Hornungia alpina: Hyaloperonospora parasitica

1a On axial parts of shoots or leaves => 2

1b On ± distinctly swollen roots erupt, at first white, later on pale brown eelworm cysts, dropping, about poppy-seed size. Heterodera humuli

2a Extensive malformations on shoot tips or on higher situated leaves => 4

2b Galls on root collar or on basal parts => 3

3a Root collar with conspicuous distorted buds, up to even 6 cm large, inside white, at surface at first glabrous, greenish to pale brown, later on fissured or wart-like, dark brown proliferations. Also encroaching onto rhizomes. Agrobacterium tumefaciens

3b Basal organs with many warts, hardly 1 mm long, ± golden-yellow, many-celled, ± joining on leaf underside into crusts; or into ridges on leaf veins, -stalks or stems. Synchytrium aureum

4a Malformations caused by fungi fruiting on outside of malformation => 5

4b Malformations caused by aphids. Phorodon humuli

5a Axial parts of often systemically infected terminal or axillary young shoots are severely stunted, ± conspicuously thickened. Leaves densely clustered, leaf blades often greatly reduced, ± deflected, spoon-like, pale green, apically rapidly decreasing in size, covered on the underside with dense, dark violet down of conidiophores. Pseudoperonospora cubensis

5b Almost identical malformations, which are on upperside as well as underside, covered by a mealy white dusting, later on often ± browned mycelium. Podosphaera aphanis

1a On above-ground parts => 2

1b Nodular swellings on roots. Ligusticum scoticum: Meloidogyne hapla

2a Malformations of vegetative plant parts => 3

2b Inflorescence disfigured, flowers greened. Ligusticum mutellina, scoticum: Tegonotus scoticus

2c Similar malformations on Ligusticum mutellina are induced by: Aceria peucedani

3a Malformations caused by animals => 4

3b Malformations caused by fungi => 4

4a Development of leaf blade stunted, spoon-like deflected downwards, curled; in case of strong infestation yellowing early. Ligusticum mutellina, scoticum: Tegonotus scoticus

4b Leaf midrib and stalks of leaflets shortened, distorted; leaf blades curled and deflected, nest-like. M. athamanticum; Ligusticum mutellina: Philaenus spumarius

5a Galls with sori on their surface => 6

5b Spindle-shaped, vitreous, at first ± pale green, later grey-brown bulges which reach a length of up to 10 mm on stems or petioles but are often only 1 mm across on midrib and veins. Ligusticum mutellina, mutellinoides; Meum athamanticum: Protomyces macrosporus

6a Bulging swellings, yellowish and usually similarly margined on stem parts and main veins of leaves, bearing aecia. Ligusticum mutellina:. Fungus host-alternating; uredinia, telia on Persicaria alpina, bistorta => 8

6b Similar, but brown to black telia bearing bulges => 7

7a Teliospores 3-celled, bearing several long sturdy spines. Ligusticum mutellina; Meum athamanticum: Nyssopsora echinata

7b Teliospores 2-celled. Ligusticum mutellinoides, scoticum: Puccinia thomasii

8a Aecia dense, cup-shaped, the margin not bent outwards. Ligusticum mutellina; Meum athamanticum: Puccinia mei-mamillata

8b Aecia countersunk, opening with pore, not with cup. Ligusticum mutellina; Meum athamanticum: Puccinia bistortae

8c Spindle-shaped, weak swellings on leaf axis and veins, also on stems, soon bearing telia. Ligusticum scoticum: Puccinia halosciadis

1a On above-ground parts => 2

1b Root hairs variously swollen, usually bottle- or club-shaped; each containing a rotund, hollow, multipartite spore ball. G. fluitans: Sorosphaerula radicalis

2a On culms and leaves => 3

2b Whitish, at surface yellowish or brownish patches, which envelope a large area of the upper part of stem, of which further development is stunted. Node of stem rarely swollen, encircled by fungus stroma, yellowish when mature; several nodes may be affected; flowering stunted; stroma contains narrow asci and filamentous spores. G. striata, Glyceria sp.: Epichloë glyceriae

2c On inflorescences or flowers. Spikelets elongated; flowers ± greened, bleached if strongly infected. G. fluitans: Aceria tenuis

3a Malformations caused by fungi => 4

3b Leaf blade rolled, irregularly curved and twisted; caused by a dull green to reddish, 2 mm long aphid. G. declinata, fluitans, maxima, notata, striata: Sipha glyceriae

3c Yellow-red midge larvae living under leaf sheaths. G. maxima: Octodiplosis glyceriae

4a Fungus, usually completely pervading many shoots, sporulates mainly all around the internodes of the at least initially excessively elongated, non-flowering shoots. G. fluitans: Tranzscheliella hypodytes

4b The infestation usually affects all shoots of infected plant, in which sterile culms often grow initially rigidly erect and bear stunted, pale-green leaves. The smut sori extend over the complete length of the leaf blades in several parallel stripes. G. arundinacea, declinata, fluitans, lithuanica, maxima, nemoralis, notate: Ustilago filiformis

4c Long conspicuous stripes on chlorotic leaf tissue caused by rust fungus. Glyceria spp.: Puccinia striiformis

= In similar sori on G. fluitans, notata: Ustilago davisii, differing from U. longissima by its larger spores (8–14 x 6–12 μm)

= Another smut fungus, sporadically occurring on Glyceria, distinguished by its spores clustered in balls, belongs to the Urocystis agropyri species complex

1a On leaves and scapes => 4

1b On roots or tubers => 2

2a Malformations on tubers => 3

2b Roots with nodular swellings. G. x gandavensis, x hybridus: Meloidogyne hapla

3a Bulge-like galls on tuber surface => 4

3b Yellow-brown large “leafy galls”, tuber- or scale-shaped accumulations at the base of the tuber, up to 40 mm in cross section. Gladiolus spp.: Rhodococcus fascians

4a Blackish, partially yellow margined bulge-like swellings on leaves, stems and tubers. Releasing a dark brown powder consisting of spore balls after breaking open. G. imbricatus, italicus, palustris: Urocystis gladiolicola

4b Less severely infected tubers that are partially destroyed internally develop only some variously bleached and curved leaves, bearing ± oblong spindle-shaped, spongy bulges. Gladiolus spp.: Ditylenchus dipsaci

1a On above-ground parts => 2

1b Roots with spindle- to nodule-shaped swellings. G. parviflora: Meloidogyne hapla

2a Distortion of leaves => 4

2b Galls mainly on stems => 3

3a Initially hyaline, later on browned, glabrous ± spindle-shaped swellings of the stems on all sides or, if on one side, bent, occasionally on petioles and leaf veins, even on involucral bracts, exceptionally on adventitious roots; of various shapes and dimensions. Young plants swollen at stem base. G. parviflora: Protomyces buerenianus

3b Blunt, spongy swellings of the stems, ± uneven, at their surface, the inside with eelworms. G. parviflora: Ditylenchus dipsaci

4a Tight curling of the locally intensively green coloured leaf blade caused by a froth-covered nymph. G. quadriratiata, parviflora: Philaenus spumarius

4b Wrinkling and downward bending of the leaf blade. G. parviflora: Unidentified aphid

1a Expanded galls on all green parts, according to the plant part affected => 3

1b Inconspicuous galls, consisting of a single swollen epidermis cell, on all green parts => 2

2a 1-celled warts, very small, punctiform, slightly protruding, yellowish; inside the spindle-shaped, swollen nutritive cell is a single 100 x 150 μm, or several (up to 10), globular or oval to flattened resting sporangia with colourless contents. G. pratensis: Synchytrium punctatum

2b Galls similar. The nutritive cell contains 1–3 resting spores, with red-orange or yellow contents. G. lutea, minima, pratensis: Synchytrium laetum

3a Bulging galls caused by smut fungi => 4

3b Leaves stunted; with irregular, pale, rugose-spongy swellings at base. Leaf blades twisted and curved. G. pratensis: Ditylenchus dipsaci

4a Rotund to oval smut pustules, about 2–10 mm long bulging, bladder-like, sometimes coalescing, which erupt rather late with longitudinal slits and release a blackish-olive-brown spore mass. Spores single. Gagea spp.: Vankya ornithogali

4b Similar but predominantly isolated, often extensive smut bulges on leaves and scapes; spores single or clustered in balls of 2–3 (5), enveloped by sterile auxiliary cells. G. pauciflora: Urocystis ornithogali

1a On parts above ground => 2

1b Roots with nodular swellings. F. vaillantii: Meloidogyne hapla

2a Malformations of organs at shoot tip, fruits => 4

2b Galls on base of stem => 3

3a Unilocular stem gall with a solitary weevil larva. F. officinalis, vaillantii: Sirocalodes quercicola and/or S. depressicollis

3b Petioles in most cases mainly stunted at base, thickened, ± pale green, spongy, swollen; containing the inducers inside. Fumaria spp.: Ditylenchus dipsaci

4a Malformations caused by animals => 5

4b Malformations caused by fungi, developing grey-violet down on the surface of the malformations. Fumaria spp.: Peronospora affinis

5a Malformations densely crowded with black aphids. Fumaria spp.: Aphis fabae

5b Malformations caused by froth-covered nymphs. Fumaria spp.: Philaenus spumarius

5c Larva solitary in a slightly enlarged, and partially reddish coloured fruit; hibernation as larva in the (usually fallen) gall. F. cf. agraria, officinalis:
Neaylax versicolor

1a Malformations on leaves => 3

1b On inflorescence and in flowers => 2

2a Centre of (partial) umbel swollen, globular or club-shaped; gall mostly uni-, also multi-chambered, each containing a red larva. Lasioptera carophila

2b Fruit strongly swollen, often reddened; protruding above the umbel. Containing a single orange-red larva. Kiefferia pericarpiicola

3a Malformations caused by animals => 4

3b Leaves rigidly erect, longer stalked than normal ones; leaf blades pale, narrower, sometimes curved and twisted, usually bearing spermogonia over whole surface and aecia on underside. Puccinia sii-falcariae

4a Malformations with conspicuous curling and distortion of the leaf blade => 5

4b Irregular thickenings, up to about 10 mm long, pale, wrinkled, often variously curved, often radiating from the midrib ± into the leaf blade; sometimes arranged into several rows. Ditylenchus dipsaci

4c About 8–15 mm long, broad spindle-shaped, strongly bent, glabrous swellings on petioles or midribs of leaves. On the inside of the curving is a depression containing the causer. Planchonia arabidis

5a Leaf sheaths swollen, belly-like, ± bulging, simultaneously often curling and twisting of leaf blades caused by yellowish aphids. Ammiaphis sii

5b Leaf blade strongly deflected, undulately curled, sometimes converging, nest-like. Philaenus spumarius

1a Wart-shaped, small swellings on ± distorted green organs => 4

1b Malformations expanded => 2

2a Malformations at least partially with abnormal pubescence or down of branched conidiophores => 3

2b Axis bulging over variable length, sometimes curved; galls at surface with rimmed depressions, containing froth-covered nymph. E. picta: Planchonia arabidis

3a Systemic diseased shoots developing faster than healthy ones; leaves paler, narrower, deflected at margin, appearing arched, with whitish down of branched conidiophores on underside. E. nemorosa, rostkoviana, stricta: Plasmopara euphrasiae

3b Complete plant ± distorted, often non-flowering, abnormally pubescent over large parts. Leaves often bent, spoon-like, yellowish or reddish discoloured, white-erineum on underside. Flowers, if present, disfigured, often transformed into rotund masses of small, abnormal leaves. Excessive branching. Euphrasia spp.: Aceria euphrasiae

3c Young growth and in inflorescences which become slightly curved and stunted; malformations caused by aphids. E. frigida: Hyperomyzus thorsteinni

4a Warts greenish, hemispherical, 0.3–1 mm across, usually clustered, close to ground on stems and leaves of dwarfed plants; occasionally also on calyx of flowering plants. E. picta: Physoderma negeri

4b Warts similar but golden-yellow translucent, on basal organs, isolated or occasionally joined into crusts or ridges. E. picta: Synchytrium aureum

1a On plant parts above ground => 2

1b Roots with nodular swellings. D. elatum: Meloidogyne hapla

1c Leafy galls, caused on the root collar by Rhodococcus fascians

2a Closed stem galls, contain insect larva => 3

2b Leaves or petioles with rotund to oval, yellowish, aecia bearing bulges. Consolida ajacis, hispanica, regalis; Delphinium spp.: Puccinia actaeae-elymi

2c In similar malformations on Consolida ajacis, regalis; Delphinium cashmerianum, elatum, exaltatum develop aecia of a less cecidogenic rust fungus alternating on Elymus caninus: Puccinia actaeae-agropyri

3a Small spindle-shaped swelling on stem, 5–10 mm long and 2–4 mm in cross section, red or brown, close to an insertion of leaf, with large cavity. Consolida hispanica, regalis; Delphinium longipes: Thamnurgus delphinii

3b Stem just below the still undeveloped inflorescence ± spindle-shaped, or irregularly barrel-shaped, swollen over a length of 20–35 mm. The increasingly developed, also outside the gall irregularly eaten, pith containing a single or several larvae. Delphinium elatum, ? oxysepalum: Ranunculiphilus pseudinclemens

1a Galls on parts above ground => 2

1b Root collar with conspicuous, at first succulent, later on ± woody, cancer-like proliferations. D. mezereum: Agrobacterium tumefaciens

2a On twigs, shoot tips or leaves => 3

2b Perianth at base rounded, swollen, disfigured, up to 3–5 mm long. Containing several, whitish larvae. D. gnidium, laureola, mezereum, striata: Dasineura daphnephila

3a On shoot tips or leaves => 4

3b Swelling of twig, about 50–60 mm long, 5 mm broad, contains long tunnels sometimes with several larvae. D. gnidium, laureola, mezereum: Phyllobrostis eremitella

4a Leaves loosely rolled downwards and curved. D. aureola, mezereum, striata:
Macrosiphum daphnidis

4b More or less distinct malformation on leaves. D. mezereum: Aculus daphnes

4c Leaves on stunted shoot tip clustered, tuft-like, elongated, locally thickened, ± discoloured red, developing into an oblong-oval or spindle-shaped gall, up to 30 mm long and 5–10 mm thick, sometimes sickle-shaped. Contains several white larvae. D. cneorum, laureola, mezereum, striata: Dasineura daphnes

1a On flowers or fruits => 4

1b On vegetative organs => 2

2a Leaf blades converging, distorted or curled => 3

2b Leaf margin narrowly rolled upwards, more rarely downwards, discoloured.
Unidentified gall mite

3a Young axis locally stunted; several leaves clustered, converging, ± nest-like. Leaf blades curled, deep green close to the froth-covered nymph. Philaenus spumarius

3b Leaf blades slightly clustered, curved and distorted. Inducer unknown – ? insect

4a On fruits; malformations facultative, usually minor => 5

4b Flower buds enlarged, cartilaginously thickened; ± reddish; later on rupturing, with thick, short lobes. Containing white to yellowish, jumping larva. Contarinia vincetoxici

5a Fruit slightly swollen; often hardly changed, sometimes ± wrinkled and discoloured. Containing several slender, white, jumping larvae. Contarinia asclepiadis

5b Fruit swollen, sometimes curved, ± yellowish, reddish or violet. Containing many cylindrical larvae. Euphranta connexa

1a On leaves and stems => 2

1b On shoot tips or in the leaf axils densely crowded about 10–15 mm long tufts of shoot-like proliferations, composed of scale-shaped leaves. Shoot stem stunted; sometimes with fasciation: Aceria chondrillae

= In flower heads may develop larvae of the gall midge Jaapiella chondrillae

2a Malformations mainly or exclusively on the stems => 4

2b Malformations of the leaves => 3

3a Leaf blade with rotund pustules, up to 5 mm long, protruding on the upper side, ± reddish, usually brighter in the middle, closed on the underside only by the smooth epidermis, with translucent yellow-red larva. Cystiphora schmidti

3b Leaf blade curled with undulate margin. Uroleucon chondrillae and/or Chondrillobium blattnyi

4a Galls caused by animal inducers => 5

4b Stem, sometimes the leaf stems with short, wart- to bulge-shaped swellings up to twice the size of the respective plant part. With brown sori on the upper side. Puccinia chondrillina

5a Galls about 40 mm long and 15 mm broad, consisting of two swollen parts separated by a constriction. Timaspis chondrillae

5b Shoots with lateral, oval galls, up to 2.5 mm long and 0.75 mm wide. Cystiphora schmidti

1a On stems or leaves => 2

1b Fruit swollen, ± disfigured. M. litorale, minus: Rhinusa antirrhini

2a Galls on stems => 3

2b Shoot tips, if heavily infected, slightly stunted, slightly thickened; the inserted leaves clustered, leaf blades stunted, their margins rolled, ± distorted; bearing down of branched conidiophores. M. minus: Peronospora linariae

2c Complete plant disfigured, additionally branched; leaves curled and twisted; flower primordia, if present, aborted. M. minus: Cause unknown – ? gall mite

3a Shoot axis with conspicuous, one-chambered, rotund or multi-chambered, oblong swellings. Each chamber containing a single larva. M. minus: Rhinusa pilosa

= Inquiline in galls of R. pilosa: Rhinusa eversmanni

3b Stem with weak spindle-shaped swelling. Containing a single larva. M. minus: Mecinus janthinus

1a In leaves or inflorescences => 3

1b In stem parts => 2

2a Root collar bumpy swollen. C. vulgaris: Ditylenchus dipsaci

2b Stem gall. Spindle-shaped very elongate swelling, 35 x 5 mm. Large thin-walled larval chamber with lateral large round exit hole. A. serratuloides: Unidentified lepidopteran

3a In inflorescences => 5

3b In leaves => 4

4a Leaves at primary veins already in early spring with minor oval swellings, yellowish, up to 0.5 mm with pycnidia on the upper side and areas with primary, cinnamon-brown, dusty uredinia. C. acaulis: Puccinia carlinae

4b Leaf blade transformed into a fleshy tissue, elliptical, about 11 mm high and 5 mm in cross section; surface green, covered with fine white hairs and leaf lobes provided with spines. Large irregular thick fleshy-walled cavity, dark coloured. C. gummifera: Unidentified stem eelworm

4c Leaf blade covered with a thick layer of long whitish hairs. C. gummifera: Aceria carlinae

5a Malformations of receptacle => 6

5b Flowers greened. Excessive branching. C. vulgaris: Cause unidentified – ? gall mite

6a Capitula swollen, hardened, remaining ± closed, with several long oval gall chambers, placed upright on receptacle. One larva per chamber without distinct head capsule. C. vulgaris: Urophora solstitialis

6b Capitula slightly enlarged; the fleshy parts consumed by a larva with a distinct head capsule. C. vulgaris: Larinus planus

6c Similar malformations in greatly hardened receptacles can be caused by caterpillars of Metzneria aestivella subsp. aestivella

1a On flowers or leaves => 3

1b On root collar or on roots => 2

2a Rotund, succulent, usually one-sided, one-chambered gall, up to 8 (10) mm long, on root collar. Containing a single larva. B. erucago. Ceutorhynchus assimilis

2b Roots with conspicuous, succulent, compact swellings, with masses of minute spores in many cells. B. erucago, orientalis: Plasmodiophora brassicae

3a On leaves => 4

3b Flower buds swollen, unopened. Containing a single or several whitish to pale yellow, jumping larvae. B. erucago, orientalis: Contarinia nasturtii

4a Malformations caused by animal inducers => 5

4b Leaf blades of younger leaves often close to main venation with minor, pale green upward swellings; on the underside with a white down of branched conidiophores. B. orientalis: Peronospora buniadis

5a Basal leaves with expanded loose downward rolls, usually on one side. Infected leaf blade parts ± bumpy, arched, darker green; on underside a single or several froth-covered nymphs. B. orientalis: Philaenus spumarius

5b Petioles or axis with spindle-shaped swellings, 10–15 mm long, also deep green inside. Containing a single larva. B. erucago: Ceutorhynchus chalybaeus

1a On leaves => 2

1b Roots hardly changed, with giant cells inside at proximal part of eelworm. The first white, soon yellow, eventually brown females (cysts) detach from the roots and drop when mature. Globodera rostochiensis

2a Malformations caused by animals => 3

2b Leaf blade with slightly thickened, yellowish, later on pale brownish spots; with white aecia on underside, spermogonia on upper side. “Aecidium belladonnae“

3a Large parts of leaf blades, often loosely rolled downwards over its top and mostly one-sided; strongly curled and deep green, especially close to the froth-covered nymph. Philaenus spumarius

3b Leaf blade of single or several terminal leaves slightly deflected and curled on all sides. Macrosiphum euphorbiae

3c In similar malformations. Myzus persicae

1a On parts above ground => 2

1b Roots with nodule-shaped swellings. A. carniolica, major: Meloidogyne hapla

2a Malformations with sori of fungi on surface => 4

2b Malformations caused by insects => 3

3a Leaves with ± thickened folds, contain white midge larvae. A. major: Macrolabis sp.

3b Leaves converged downwards, nest-like; curled and dark-green close to the froth-covered nymph on underside. A. carniolica: Philaenus spumarius

4a Leaf veins and-stalk bulging, thickened, distorted. Bulges yellowish, soon bearing brown 2-celled telia. A. major, minor: Puccinia astrantiae

4b Leaf blade with hemispherical swellings which are ± spindle-shaped on leaf veins. Aecia countersunk; peridium not protruding. A. minor: Puccinia polygoni-vivipari

1a Malformations on stems and leaves => 3

= (For root swellings see Vaccinium)

1b Galls on lateral buds or on fruits => 2

2a Buds enlarged and disfigured. A. uva-ursi: Aceria jaapi

2b Young berries disfigured, prematurely reddened and dropping; often ± angular, split to the middle; lobes sometimes elongated, snout-like. Usually containing several orange-coloured larvae. A. uva-ursi: Unidentified gall midge

3a Malformations only on leaves => 4

3b Malformations of complete shoots, partially witches’ broom-like. Leaves smaller or larger than normal ones; sometimes arched, pale green or ± intensively brown-red coloured; partially with whitish down on underside. A. uva-ursi: Exobasidium uvae-ursi

4a Leaf blade with loose, ± discoloured, slightly succulent marginal downwards roll. Containing several orange-red larvae. A. uva-ursi: Unidentified gall midge

4b Larger or smaller segments strongly arched downwards, depressed on upperside; leaf blades sometimes groove-shaped; often conspicuously reddened. Infestation occasionally at shoot tips encroaching onto all parts. Axial parts swollen, leaves reduced, succulent thickened, spoon-like. Infected parts on underside of leaf blade at maturity of fungus covered with chalk-white layer. A. alpina, uva-ursi: Exobasidium vaccinii

4c Leaves with small thickened orange spots, sometimes also on thickened stems. A. uva-ursi: Exobasidium sydowianum

4d Leaves slightly enlarged and thickened, yellowish white to dark purple; shoots clustered, slightly elongated and deformed. A. alpina: Exobasidium angustisporum

1a Malformations on the plant surface not occupied by fungi => 2

1b Leaf blade on the underside with round 1 (2) cm large, yellowish to reddish-brown spots with many close and distinctly bordered aecia. Sporulating areas on the veins with slightly cushion-like bulges. Puccinia poae-aposeridis

2a Galls on the leaf blade or on the margin => 3

2b Hyaline callus on the midrib, radiating to lateral veins; venation strongly swollen; leaf blade sometimes ± malformed; centre yellowish discoloured. Spores predominantly in phloem. Protomyces kreuthensis

2c On the leaf blade, in many usually brownish spots, up to 1 mm long, sometimes slightly bulged. Entyloma aposeridis

3a Leaf blade glabrous, margin rolled upwards. Unidentified thrips

3b Leaf blade on the underside with small depressions and corresponding swellings on the upper side; strongly infected leaves sometimes ± twisted and rolled at the margin. Trioza dispar

3c Browning of leaf blade; at high densities rusting may occur. Epitrimerus protrichus

1a Galls of various shape on panicles, flowers or fruits => 4

1b Galls on vegetative parts => 2

2a Localised galls on stems or leaves => 3

2b Young plants severely stunted. Shoots swollen, spongy especially at base; leaves reduced and bent. Ditylenchus dipsaci

3a Stem with weak, locally rimmed depressions below the slightly swollen sheath. Containing single orange-yellow larvae. Lasioptera calamagrostidis

3b Leaf blades at base usually with reddish to violet, slim bulging, swellings, 5–30 mm long. Anguina graminis

4a Malformations of ovaries => 5

4b Axial parts of panicles especially at base strongly wriggled, therefore appearing shortened; spikelets gathered together, usually remaining closed; flower parts and glumes not enlarged, sometimes greened. Unidentified eelworm

4c Inflorescence and flowers disfigured. Reproductive organs aborted. Glumes twisted or irregularly folded; in case of weaker infestation often dark red or violet, bleached if strongly infected. Aceria tenuis

5a Ovaries swollen bottle-shaped, usually discoloured violet, glumes not enlarged. Anguina agrostis

= Sometimes the sac fungus Dilophospora alopecuri occurs in ovaries of many grasses when eelworms are associated

5b Ovaries temporarily swollen, soon transformed into rotund to oblong smut grains, in the pendant panicles. Fresh sori smelling. Plant hardly disfigured. Tilletia separata

1a On leaves or on branches => 2

1b Inflorescence with abnormal felt-like pubescence. A. hippocastanum: Unidentified gall mite

2a On leaves => 3

2b Thicker branches with spindle- to club-shaped swellings, bearing Viscum album

3a Localised galls on leaf blade => 4

3b Leaves rolled downwards. A. hippocastanum, pavia: Aphis fabae

4a Lenticular gall on leaf underside. A. hippocastanum: Unidentified gall midge

4b Abnormal tufts of hairs on underside of vein axils; on upper side a corresponding arching. Hairs many-celled, long, weakly club-shaped. Aesculus spp: Aculus hippocastani

4c Rusting and abnormal hairiness of leaf blade. A. hippocastanum, glabra, neglecta: Shevtchenkella carinata

1a Bulging or expanded thickenings caused by smut- or rust fungi => 2

1b Above ground organs often with many small, glass pearl-like, mainly 1-celled wart-shaped galls. Synchytrium anomalum

2a Malformations caused by fungi fruiting at gall surface => 3

2b Bulges on shoot parts above or below ground, containing black smut spores. Melanotaenium adoxae

3a Malformation covered with aecia => 4

3b The fungus develops only dark brown sori with 2-celled telia. Puccinia adoxae

4a Aecia on leaf underside rather uniformly distributed or on petioles and stems loosely distributed on ± thickened pads. Puccinia argentata

4b Aecia, as in previous rust; uniformly distributed, more dense or loose, usually over large areas and soon systemically infected, pale plants. Puccinia albescens

1a On parts above ground => 2

1b Roots with conspicuous swellings, up to 8 mm long and 5 mm broad, rotund- to oblong-oval. Sempervivum spp.: Meloidogyne hapla

2a Malformations partially excessively pubescent, usually caused by gall mites => 3

2b Several to many leaves of the rosette upright, pale green, narrowed, partially elongated, up to twice the normal size; with small, sunken, orange-red, conically protruding spermogonia and scattered aecia-like sori on upper side. Jovibarba globifera & subsp. arenaria + hirta; Sempervivum arachnoideum, calcareum, montanum, tectorum, wulfenii: Endophyllum sempervivi

3a Malformations densely pubescent => 4

3b Complete plant shortened and disfigured. Jovibarba globifera: Unidentified gall mite

3c From S. arachnoideum has been reared Aizobius sedi

4a On Jovibarba hirta. Leaves paler and densely pubescent, usually with many small, cone-shaped outgrowths, especially on upper side. Unidentified gall mite

4b On S. montanum. Rosette disfigured, ± irregular; grey-looking because of dense pubescence. Leaves sometimes with wart-like protuberances. Flowers leafy (phyllanthy). Unidentified gall mite

1a On flowers or flower parts => 4

1b On vegetative organs => 2

2a Expanded malformations on stems and leaves => 3

2b Leaf blades with several rotund pads, up to about 5 mm broad, protruding on underside; yellow-brown, sometimes slightly swollen, soon covered with brown spores. Occasionally more elongated sori on main veins and young stems. S. cerastioides, ocymoides, officinalis, orientalis, persica: Puccinia arenariae

3a Young shoots stunted, thickened and shortened, leaves ± clustered; their bases often spongy, strongly swollen; leaf blades distorted and curled. Saponaria spp.: Ditylenchus dipsaci

3b Leaf strongly deflected, ± bent and curled, deep green at infestation site; sometimes several leaves similarly disfigured on stunted shoot tips which are usually cracked on one side. Saponaria spp.: Philaenus spumarius

4a Malformation of flowers, or predominantly of anthers, caused by fungi => 6

4b Malformations of flowers caused by animals => 5

5a lowers unopened variously swollen conically. Containing several yellowish, jumping larvae. S. officinalis: Contarinia steini

5b Slightly bloated, ± largely unopened calyx encloses the other flower parts which are transformed into scale-like, ± greened leaves. Saponaria spp.: Cause unknown – ? gall mite

6a Flower buds ± globular, swollen to about pea-size, ± brown-red discoloured galls. Inner parts soon largely destroyed. Bud at first unopened, eventually bursting open and with dusting of brown-yellow spore balls. S. ocymoides, officinalis: Thecaphora saponariae

6b Anthers ± globularly swollen in unopened, usually little altered flowers, rigidly connected to their filaments, soon filled with reddish- to brown-violet spore masses. S. lutea, ocymoides, officinalis, pumilio: Microbotryum violaceum

1a Malformations on parts above ground => 3

1b Galls on root collar => 2

2a Root collar with weakly globose protruding one-chambered swelling, less than 10 mm long, laterally attached to root as a glabrous gall. R. luteola:
Unidentified snout beetle

= Nodular malformations have been reported on R. luteola, which may be attributed to Meloidogyne hapla

2b Root collar with mainly one-sided, 20–25 mm long, 15–20 mm broad, facultatively originating swellings, soon bearing dying rosette leaves. Containing several larvae. R. luteola: Unidentified snout beetle

3a On inflorescences, shoot tips or leaves => 4

3b Stem with spindle-shaped swelling. R. luteola: Unidentified snout beetle

4a Malformations caused by animal parasites => 5

4b Axial parts of leaves with at first porcelain-white, closed bulges, later on with mealy dusting. R. luteola: Albugo resedae

4c Upperside of the leaf with yellow spots. Underside with a brownish fungal down of erect conidiophores that apically several times are dichotomously branching, each terminal branch ending in an ovoid conidium. R. lutea, luteola: Hyaloperonospora crispula

5a Internodes of stem twisted, ± flattened, strongly curved. Flowers clustered. R. lutea: Unidentified aphid

5b Leaves clustered ± nest-like on severely stunted shoot tips, ± stunted, with several converging, curled, deep green close to the froth-covered nymph. Reseda spp.: Philaenus spumarius

1a On flowers or fruits => 4

1b On leaves and occasionally on stems => 2

2a Malformations caused by aphids => 3

2b On the leaf blades, even on calyx lobes, rotund, elongated oval, yellowish, aecia and spermogonia bearing bulges, weakly protruding on underside stronger on leaf axis, -stalk or stem. Pulmonaria spp.: Puccinia recondita

3a Basal leaves with transverse- or marginal roll downwards, also upwards. Leaf blades irregularly curled or bulging. Apterous aphids 1.8–2.9 mm long. Body pear-shaped, pale yellowish to green, with a dark, green spot at each insertion of pale, very short siphunculi. P. obscura, officinalis: Aulacorthum solani

= As causer of disfigured leaves on P. obscura, the aphid Aphis symphyti has been reported, living mainly on Symphytum

3b Malformations similar. Aphid 1.5–2 mm long, pale yellowish to yellow-green. Siphunculi pale, longer than those of previous species, reaching about 1/5 to ¼ of body length. P. officinalis: Brachycaudus helichrysi

4a Flowers thickened, unopened. Containing several white larvae. P. obscura, officinalis: Unidentified gall midge

4b Mericarps greatly enlarged, as long as calyx. Pistil slightly changed. Containing orange-red larvae. P. montana, etc.: Unidentified gall midge

1a Galls on above-ground parts => 2

1b Roots with several nodule-shaped, massive swellings. P. paradoxus: Meloidogyne hapla

2a Galls wart-, cushion- or bulge-like => 4

2b Extended malformations on the leaf blades => 3

3a Leaves mostly stunted, leaf blades markedly curved downwards, sometimes bag-like, undulating, curled. Rolls partially markedly thickened. P. hybridus: Inducer unknown

3b eaf blade parts strongly curved downward, curled, the site of infestation dark green close to the froth-covered nymph. P. hybridus: Philaenus spumarius

4a Less than 1 mm long, multicellular, usually yellow, sometimes coalescing warts on green parts situated close to the ground. Petasites spp.: Synchytrium aureum

4b Larger, cushion- or bulge-like malformations => 5

5a Rotund or oblong flat aecia cushions, in yellowish or reddish spots, up to about 6–10 mm long situated, on leaf blades and veins, rarely on petioles. Petasites spp.: Aecidium petasitidis

5b Rotund cushions, the underside clearly bulged, and occupied by dark brown telia. P. frigidus, paradoxus: Puccinia expansa

1a On parts above ground => 3

1b On roots => 2

2a Nodular swellings in root. O. sativus: Meloidogyne hapla

2b Often only small nodules attached to roots, usually oval, more rarely cylindrical, apically sometimes flattened or grooved. Ornithopus spp.: Rhizobium lupini

3a Malformations on leaves, as well as conspicuously on petioles and stems => 4

3b Leaflets rolled upwards or folded together; sickle-shaped, also spirally distorted. Flowers atrophied and aborted; sometimes develop leaves instead of bracts. Plants often ± stunted, infected extensively. Diseased parts sometimes abnormally haired. O. perpusillus, sativus, ? compressus: Aceria plicator

4a Stems with spongy swellings on conspicuously stunted young plants. Inserted leaves ± stunted and disfigured. Many eelworms live in the prematurely withering tissue. O. perpusillus, sativus: Ditylenchus dipsaci

4b Systemically infected young plants or shoots often largely stunted in longitudinal growth, rigidly erect. Leaves and leaflets reduced, thickened due to defective differentiation of tissue, soon covered with a dirty grey down of branched conidiophores. O. perpusillus, pinnatus, sativus: Peronospora ornithopi

1a On parts above ground => 2

1b Nodular, almost rotund galls on roots. O. fruticosa: Meloidogyne hapla

2a Expanded malformations on single or several organs => 4

2b Small wart-shaped galls on leaves and stems => 3

3a Warts multicellular, orange to crimson-red translucent, often densely clustered, mainly on basal plant parts. O. biennis: Synchytrium fulgens

3b Warts multicellular, glass bead-like. O. biennis: Synchytrium mercurialis

4a Causers on host surface and visible with naked eye => 6

4b Causers inside galls or, if on outside, only microscopically => 5

5a Outer rosette leaves stunted and disfigured. Midrib spongy, swollen. Neighbouring leaf blade areas undulate-lacerate. O. biennis: Ditylenchus dipsaci

5b Malformation of complete, severely stunted plants with partially greened flowers. O. biennis: Inducer unknown

6a Axial parts of shoots stunted or curved on one side; leaves ± clustered, deflected over tip and margins, ± curled and locally deep green. Oenothera spp.: Philaenus spumarius

6b Plant distorted, shoot axis shortened. Leaves smaller, folded between side veins, also ± curled. Flowers greened and thickened Oenothera spp.:
Brachycaudus cardui

=Aphis holoenotherae has been recorded from many Oenothera species. This is the only aphid that is fully dependent on evening primrose. Not a true gall causer

1a Galls on parts above ground => 2

1b Roots conspicuously curved and swollen. N. officinale: Spongospora nasturtii

= The snout beetle Ceutorhynchus assimilis, inducing root collar galls on many crucifers, also occurs on N. officinale, but occasionally without causing galls

= The cyst developing eelworm Heterodera cruciferae has been recorded on Nasturtium

2a Malformations on vegetative organs => 3

2b Flowers swollen, unopened. Corolla stunted, like other parts disfigured and ± thickened. Larvae whitish to lemon-yellow. N. microphyllum, officinale: Contarinia nasturtii

3a Malformations caused by fungi, with fruiting bodies on their surface => 4

3b Axis of young shoots stunted, inserted parts clustered. leaves or leaflets deflected, curled and discoloured deep green close to the froth-covered nymph. N. microphyllum, officinale: Philaenus spumarius

4a Fungus sori dense, at first closed, glossy, porcelain-like, conidia developing in rows, later on with mealy dusting. N. microphyllum, officinale: Albugo candida

4b Fungus fruiting on branched conidiophores, developing in loose down of branched conidiophores. N. officinale: Hyaloperonospora nasturtii-aquatici

1a On parts above ground => 3

1b On roots or root collar => 2

2a About pea-size, ± globular galls on root collar containing a curved beetle larva. Ceutorhynchus assimilis

2b Main- and side roots with conspicuous, spindle-shaped to cylindrical, fleshy galls of variable size. Plasmodiophora brassicae

3a On flowers => 6

3b On vegetative organs => 4

4a Galls caused by animals => 5

4b White bulges on leaves and stems, at first glossy, porcelain-like, later on with mealy dusting. Albugo candida

5a Margins of young leaves bent upwards; leaf blades variously wrinkled or undulate and discoloured pale green. On vegetative shoots several terminal leaves are sometimes accumulated and conspicuously disfigured. Brevicoryne brassicae

5b Terminal leaves or axillary buds clustered; the outer one ± disfigured, at base discoloured and ± thickened, enveloping the bud-like inner leaves. Containing several lemon-yellow, jumping larvae. Contarinia nasturtii

6a Flowers swollen, unopened. Larvae white, non-jumping. Gephyraulus raphanistri

6b Similar galls. Larvae lemon-yellow, jumping. Contarinia nasturtii

1a On stems and leaves => 3

1b On flowers => 2

2a Flowers ± swollen globularly, unopened. Inner organs soon destroyed and replaced by spore balls consisting of a yellowish-brown powdery dust. Arenaria pungens; Minuartia hybrida: Thecaphora saponariae s.l.

2b Flowers outwardly not conspicuously changed; anthers shortened and swollen; later on filled with a dusty violet spore powder. M. recurva: Microbotryum violaceum

3a Malformations caused by fungi fruiting at surface => 5

3b Malformations caused by animals => 4

4a Leaves on slightly stunted shoots more densely arranged, the leaf blades a little deflected over their tip, curved upwards at margin. Honckenia peploides: Myzus certus

4b Shoot axis stunted, bent at infestation site. Leaves more clustered, leaf blades distorted. Honckenia peploides: Philaenus spumarius

5a Leaves or stem with rotund- oblong-oval, yellowish brown pads, occasionally slightly bent, protruding on underside, soon bearing a brown sorus at surface. Arenaria montana, retusa, serpyllifolia, tenuifolia; Minuartia hybrida, laricifolia, verna: Puccinia arenariae

5b Systemic diseased shoots growing rigidly erect; leaves reduced, slightly thickened and ± bent, spoon-like. On leaf underside and stem grey down of conidiophores develop. Honckenia peploides: Peronospora honckenyae

5c Bushy accumulation on twisted and thickened stems; capsules inflated. M. viscosa: Inducer unknown

1a On parts above ground => 2

1b Roots with nodular swellings. M. annua: Meloidogyne hapla

2a Inducer living inside galls => 4

2b Inducer living and/or fruiting on gall surface => 3

3a Young leaves of disfigured shoot tip curled. M. annua, perennis: Aulacorthum solani

3b Orange-yellow, soon dusty, spindle-shaped, ± distorted bulges of various length on underside of main venation, on petioles as well as occasionally on young stem parts. Patches developing on leaf blades are small, rotund and not swollen. M. perennis: Melampsora populnea

4a Stem or leaves with localised, well defined galls => 6

4b Malformations usually extending over several organs => 5

5a Large parts, sometimes the entire plants, including primordia of flowering parts, with vitreous, pearl-like, compound small warts; these often join into crusts or ridges and variously disfigure the severely stunted plants during their development. M. perennis: Synchytrium mercurialis

5b On M. annua. Young plants severely stunted. Internodes spongy, swollen, pale green. Leaves distorted, with ± swollen stalks and veins. Ditylenchus dipsaci

6a Rotund, one-chambered swellings on stems, leaf- or inflorescence axial parts. Containing a single curved larva. M. annua. Kalcapion semivittatum

6b Slender, narrow and compact, about 5–30 mm long, soon browned upwards roll of leaf margin. M. perennis: Thrips fulvipes

1a Galls on parts above ground => 2

1b Side roots often with many nodular to spindle-shaped swellings, which bear some lateral roots. Meloidogyne hapla

2a On flowers or inflorescences => 5

2b On vegetative organs => 3

3a Large parts of plant disfigured => 4

3b Leaf blade, especially in venation, with rotund to ± acuminated, oval, often conspicuous yellow to yellow-brown swellings, occurring especially on underside, which are marbled, sieve-like. Occasionally on stems. Puccinia recondita

4a Growth stunted, leaves rolled downwards, curled. Also on disfigured, ± etiolated flowers. Dictyla echii

4b Basal stem parts variously swollen, spongy ± pale green. Ditylenchus dipsaci

5a Inflorescence clustered, ball-like. Brachycaudus helichrysi

5b lowers greened, densely white pubescent, clustered, ball-like. Aceria eutricha

1a On above-ground parts => 2

1b Nodular swellings on roots. Lilium spp.: Meloidogyne hapla

1c Conspicuous galls on subterranean buds. Lilium spp.: Rhodococcus fascians

2a On severely etiolated flower buds which are occasionally galled => 3

2b Pale, sometimes brownish margined, occasionally inconspicuously swollen spots on leaves and stems, occupied by hardly protruding cups, up to 1 cm long. L. bulbiferum, canadense, candidum, carniolocum, martagon: Uromyces aecidiiformis

2c Underside of the leaves with a whitish fungal down consisting of vertical conidiophores that apically are dichotomously branching several times, each branch ending in an elliptic conidium. L. candidum: Peronospora lilii

3a Malformations lacking additional pubescence => 4

3b The ± disfigured flower buds or also the slightly spreading perianth leaves are covered with long white hairs. Containing many pale yellow larvae. L. martagon: Contarinia martagonis

4a Malformations caused by larvae with inconspicuous head => 5

4b Malformations caused by larvae with distinct head. Flower buds usually not opening, partially swollen, ± crippled, sometimes bent on one side, containing several yellowish-white, elongate oval larvae, which feed on variously disfigured stamens and ovaries or mine into the perianth leaves or also extend into the flower peduncles. L. martagon, rarely candidum: Liriomyza urophorina

5a The compact, mostly stunted buds contain several yellowish, jumping larvae. L. martagon: Contarinia lilii

5b lower buds severely stunted and etiolated. Larvae red. L. candidum: Contarinia liliacea

1a On above-ground parts => 2

1b Roots with many nodular or elongated spindle-shaped swellings, about 0.5–5 mm long and 3–5 mm broad, ± obliquely bent, crooked; containing eelworms inside the ± spongy tissue. Subanguina radicicola

2a On vegetative parts => 3

2b Inflorescence variously disfigured and bleached. Aceria tenuis

3a Malformation with black fungus sori => 5

3b Galls in culm, caused by animals => 4

4a Culm locally weakly swollen; containing a single larva. Tetramesa brischkei

4b Culm stunted in development. Upper internode sometimes appearing thickened. Inflorescence aborted, stuck in the sheaths, disfigured and ± dishevelled. Containing a yellowish-white, up to 4 mm long larva. Oscinella pusilla

5a Diseased shoots at first showing enhanced development; number of internodes and leaves increased. Organs weaker and usually paler than healthy ones. Leaves rigid, erect; plant looking weak; exceptionally with primordia of usually crippled and curved inflorescences. Internodes below the leaf sheaths, rarely also the sheaths, with expanded smut sori developing, on their surface. Tranzscheliella hypodytes

5b Smut patches on the leaves or sheaths. Ustilago striiformis

1a On above-ground parts => 2

1b Roots with several small, spindle- to nodule-shaped swellings, bearing lateral roots. Meloidogyne hapla

2a On vegetative parts => 3

2b Florets ± stunted and greened. Unidentified gall mite

3a On leaves => 4

3b Irregular swelling in stem, up to 6 cm long by 10 mm wide; containing several chambers each with a white larva or pupa. Timaspis lampsanae

4a Galls mainly in leaf blade => 5

4b Petiole, mid- and main veins or also the leaf blades of the rosette leaves already in early spring with conspicuous, usually reddish margined or overflowed, yellowish, aecia bearing bulges. Puccinia lapsanae

5a Expanded malformations of leaves => 6

5b Leaf blades with rotund wide pads, up to 5 (7) mm, usually protruding on the underside and concave on the upper side, bearing ± deep yellow aecia. Exceptionally also spindle-shaped galls on bent leaf ridges and petioles. Puccinia opizii

6a Curvings and curlings of the leaf blade caused by aphids => 7

6b Leaf blade more or less deflected, ± bulge-like curled, dark green coloured, close to the froth-covered nymph occasionally a clustering of disfigured leaves on often one-sided stunted, bent shoots. Philaenus spumarius

7a Distinct malformations of the leaf, associated with deflected curving of the margin and curling of the leaf blade. Aphid 1.8–3 mm long, straw yellow, green or reddish; wingless adults on the dorsal side with a pattern of dark spots. Siphunculi slender, cylindrical. Nasonovia ribisnigri

7b Similar malformations. Aphid 2.5–3.5 mm long, body white. Siphunculi notably swollen, widest in the middle. Hyperomyzus lampsanae

1a On parts above ground => 2

1b Oval to cylindrical, also hand-shaped to coralloid branched nodules, laterally attached to the roots; occasionally coalesced into larger clusters. Laburnum spp.: Rhizobium leguminosarum

2a On inflorescences or pods => 5

2b On vegetative organs => 3

3a On axial parts => 4

3b Buds swollen, walls of cavity inside lined with black mycelium. L. anagyroides: Asphondylia sp.

3c Leaves stunted, sometimes deflected over their top, margin ± curved downwards, leaf blade folded or curled. Laburnum alpinum, anagyroides, watereri; Lembotropis nigricans: Aphis cytisorum

4a Thicker branches with spindle- to club-shaped swellings bearing mistletoe. Laburnum spp.: Viscum album

4b Bark of young shoots with rimmed depressions, each containing a flat froth-covered nymph. Laburnum spp.: Chionaspis salicis

5a nflorescence variously disfigured. Laburnum anagyroides; Lembotropis nigricans: Aculops cytisicolus

5b Fruit with conspicuous swelling. Laburnum spp.: Inducer unknown

1a On leaflets of leaves => 4

1b On axial parts of shoots => 2

2a The causers of malformations are on the outside => 3

2b Axial parts of shoots, especially on young plants, with rotund proliferations, up to fist-size, with fissured surface. Agrobacterium tumefaciens

3a Bark of twigs with minor, rimmed depressions; containing causer. Epidiaspis leperii

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

4a Leaf roll and distortion caused by aphids => 6

4b Leaf blade and sometimes young fruits with pocks or felt-like upward archings on underside, caused by gall mites => 5

4c Leaves browned; at high densities vagrant mites may cause russeting Aculops unguiculatus

4d Yellowish spots or blotches apparent on both sides of leaflet, with whitish patches on underside. Microstroma juglandis

5a Pocks, up to 2 mm long, on both sides or only visible on upperside, rotund, if mature, black-brown with irregular cavity. Often many. Also on skins of fruits. Aceria tristriata

5b Similar pocks, protruding at the underside as up to 5 mm high cones Aceria brachytarsus

5c Crook-backed usually upward arching, reticulately striate by thickened venation and often angularly restricted. In depression on underside are whitish erinea consisting of long, cylindrical acuminate hairs. Aceria erinea

6a Loose roll of young leaflets, ± sickle-like distortion of midrib. Aphids on upper side of midrib. Panaphis juglandis

6b Similar roll of leaflets; aphids on leaf underside. Chromaphis juglandicola

1a On parts above ground => 2

1b Roots with nodular, compact swellings. F. x intermedia: Meloidogyne hapla

2a Galls on twigs => 3

2b Leaves on shoot tips ± disfigured, caused by aphids. F. suspense: Unidentified aphid

3a Rotund galls, usually situated on nodes, developing into strongly fissured woody proliferations, up to several cm large. F. suspense: Agrobacterium tumefaciens

3b Conspicuous, ± wart-like, at first succulent, later on tough galls of variable size, which develop on young shoots instead of lateral buds. Rhodococcus fascians

1a On parts above ground => 2

1b Roots with ± spindle-shaped, fleshy swellings, containing masses of minute spores. Plasmodiophora brassicae

2a Malformations at surface with sori of fungus => 5

2b Malformations caused by animals => 3

3a On stems, leaves or flowers => 4

3b Fruit slightly swollen, often oblique. Containing a single larva. Unidentified beetle

4a Complete plant ± disfigured, leaves usually shorter and broader, ± arched. Inflorescence stalk stunted. Flowers stunted tuft-like, ± greened or leafy, sometimes abnormally pubescent. Cecidophyes borealis

4b Similar malformations. Aceria drabae

4c Stem at base with swelling up to 4–7 mm long and 2–4 mm thick. Containing a single white larva. Ceutorhynchus hirtulus

5a Sori expanded, consisting of branched conidiophores. Plant completely or largely stunted, sometimes excessively leafy. Leaves etiolated, pale, slightly thickened, sometimes arched spoon-like. Infected stem parts shortened, thickened, ± bent. Inflorescences and buds stunted. Hyaloperonospora erophilae

5b At the tip of the older leaves of the rosette a faint fungal down, consisting of erect, distally strongly branched conidiophores. The plant is not disfigured, and the leaves are not bleached or galled. Hyaloperonospora praecox

5c Sori compact, at first closed, glossy, porcelain-like, with mealy dusting after rupturing; short bulge-like to long expanded. On all green parts. Infected stems often distorted; inflorescences ± disfigured. Diseased flowers with conspicuously enlarged calyx and ovaries. Albugo candida

1a On the leaflet leaf blades => 2

1b Tip of frond shortened, spirally rolled upward, including the crowded, only slightly changed side leaflets making a conspicuous nest with a white larva on the ± thickened midrib. D. carthusiana, cristata, dilatata, filix-mas: Chirosia betuleti

2a Leaf blade on underside sometimes ± fleshy because of enlarging of mesophyll- or epidermis cells; occasionally swollen, almost blister-like yellowish-brownish discoloured; fungus galls => 4

2b Malformations caused by animal parasites => 3

3a Leaflets with small pustules which contain eggs, mainly situated at margin, rapidly becoming necrotic after larval emergence. “Procecidia”, oviposition scars, not true galls. D. filix-mas: Aneugmenus coronatus

3b Margin of leaflets folded, discoloured, slightly thickened. Thelypteris palustris: Undescribed gall midge

3c Rounded swelling on rachis, about 2 mm long; containing a pale green caterpillar which bites a hole and ejects froth that covers the gall. Dryopteris spp.: Blasticotoma filiceti

4a On D. campyloptera and relatives

I Mycelium intercellular. Causes ± fleshy localised swellings in tissues of thickened leaflets. D. carthusiana, dilatata: Taphrina filicina

II Mycelium only below cuticule

a Often distinctly protruding galls on leaflets, up to 5 mm broad, ± fleshy. D. carthusiana, dilatata, “rigida var. australis”, villarii: Taphrina fusca

b Up to 5 mm long galls on leaf blade. D. carthusiana, dilatata, filix-mas: Taphrina athyrii

4b On D. affinis, borreri, carthusiana, filix-mas. Small, up to 5 mm long, often many per leaf blade, ± fleshy swollen, yellow-greenish to brownish galls: Taphrina vestergrenii

1a On parts above ground => 2

1b Roots usually with laterally inserted oblong-oval or cylindrical swellings, apically often forked or branched, almost coralloid, sometimes clustered. Dorycnium spp.: Rhizobium leguminosarum

2a On flowers or fruits => 5

2b On vegetative parts => 3

3a On shoot tips or leaves => 4

3b Shoot axis with oblong, reddened swelling. D. pentaphyllum subsp. Germanicum: cf. Melanagromyza cunctans

3c Conspicuous spindle-shaped swelling, bright red coloured, flattened on one side, with rimmed depressions containing the causer. D. pentaphyllum: Planchonia arabidis

4a Leaflets folded. D. pentaphyllum subsp. germanicum + herbaceum: Unidentified gall mite

4b Terminal leaflets of leaf folded, pod-like, reddish discoloured. Containing several at first yellowish-white later orange larvae. D. hirsutum: Dasineura sp.

4c Tip of side shoot with greenish, closed, strongly white pubescent gall, up to 7 mm long and 3 mm thick. D. hirsutum, pentaphyllum: Asphondylia dorycnii

5a Galls on pods => 6

5b lowers disfigured and ± greened, as well as other organs present on shoot tip variously disfigured organs abnormally pubescent. Dorycnium spp.: Aceria euaspis

6a Pod swollen. Inner wall covered with fungus. D. hirsutum, pentaphyllum: Asphondylia dorycnii

6b Pods swollen; mycelium absent. Containing a curved larva with head capsule. D. pentaphyllum & subsp. germanicum + herbaceum: Ischnopterapion aeneomicans

1a On above-ground parts => 2

1b Side roots with nodular swellings. D. sativus: Meloidogyne hapla

2a On vegetative parts => 4

2b On capitula => 3

3a Infected capitula often strange-looking. Several petals enlarged, ± disfigured, discoloured. Anthers and ovaries largely aborted. Loose down of branched conidiophores on petals of usually completely diseased capitula. D. fullonum, laciniatus, pilosus: Peronospora violacea

3b Many parts of capitula disfigured; diseased tissue hypertrophied, soon browning and dying. Infected fruits reduced, twice as thick as normal ones; pappus sessile, swollen. Seed coat thickened, rounded. D. fullonum, sativus: Ditylenchus dipsaci

4a Malformations on rosette leaves => 6

4b Malformations of higher situated parts => 5

5a Leaf blades of larger stem leaves, including tip, mainly deflected on one side; strongly curled and deep green close to the froth-covered nymph. Dipsacus spp.: Philaenus spumarius

5b Undescribed gall-like malformations caused by aphids. D. sativus: cf. Aulacorthum solani

= On D. laciniatus and D. fullonum the gall mite Leipothrix dipsacivagus has been described causing rusting and wrinkles on the longitudinal folds of leaves

6a Usually several inner leaves of spring rosettes infected, more erect; leaf blades narrowed, slightly thickened and ± brittle; usually to a large extent the infected parts alongside the midrib are pale green, bulging upwards over the normally coloured marginal areas, covered on underside by a dirty pale grey down of branched conidiophores. D. fullonum, laciniatus, pilosus: Peronospora dipsaci

6b Rosette leaves in spring stunted, shortened, spongy and swollen, especially at base, pale, sometimes clustered, cabbage-like. D. sativus: Ditylenchus dipsaci

6b Leaves with small gregarious pustules, less than 0.5 mm across. D. fullonum: Synchytrium succisae

1a On leaves and stems => 3

1b On roots or on root collar => 2

2a Roots with conspicuous spindle-shaped or acuminated, cylindrical succulent, compact swellings. C. abyssinica, maritima, tataria: Plasmodiophora brassicae

2b Rotund, about pea-size, one-chambered galls on root collar. Containing a single larva. C. maritima: Ceutorhynchus assimilis

3a Expanded malformations caused by aphids => 5

3b Galls of lesser expansion, ± pad- or bulge-shaped => 4

4a Galls spindle-shaped, 15‒20 mm long, also green inside, on petioles, leaf veins or thinner stems. Containing a single larva. C. abyssinica, maritima, tataria: Ceutorhynchus chalybaeus

4b At first closed glossy, porcelain-like, later on rupturing and with mealy dusting, rotund to oblong-oval pads or bulges on leaves, stems and stalks of inflorescences. C. maritima, tataria: Albugo candida

4c Stem and also axis of inflorescence usually with expanded, conspicuous, often distorted swellings, soon covered with a down of branched conidiophores. Flowers of diseased inflorescences severely stunted. Leaves of axillary shoots if infected early, ± spoon-like arched, thickened, brittle, pale green; with a dense down of conidiophores on underside. C. maritima, tataria: Hyaloperonospora parasitica

5a Complete plant disfigured, leaves rolled, flowers greened. C. maritima: Lipaphis hedickei

5b Leaf blades of basal leaves with irregular paler green, sometimes ± red-violet marbled archings. C. abyssinica, maritima: Brevicoryne brassicae

1a On inflorescences or fruits => 5

1b On vegetative parts => 2

2a Malformations caused by animal parasites => 3

2b Bulge-shaped, sometimes distorted, about 10 mm long swellings on leaf veins, -midrib and -stalk, bearing cinnamon-brown uredinia, occasionally also on younger stem parts and even in inflorescence. Puccinia conii

3a Malformations caused by aphids => 4

3b Leaf blade over large parts nest-like downwards deflected; leaf tips slightly curled and deep-green. Philaenus spumarius

4a Axis of leaf tip conspicuously distorted and twisted; leaf blades folded and curled. Aphid about 2 mm long; pale green, with pale siphunculi, these much longer than cauda, which bears an appendage. Antennae shorter than half the body length. Cavariella pastinacae

4b Malformations similar. Aphid 1.5–2.4 mm, grey-green, often blackish-brown. Siphunculi very dark, about as long as cauda. Antennae ⅓–½ body length. Hyadaphis foeniculi

5a Stalk at centre of (partial) umbel ± globular to club-shaped swollen. Inner wall covered with mycelium. Containing a red larva. Lasioptera carophila

5b Fruit strongly swollen, globular to rotund-oval; galls protruding above the umbel; glabrous, ± reddened. Containing an orange-red larva. Kiefferia pericarpiicola

5c Inside disfigured fruits of C. maculatum develop uredinia of Puccinia conii

1a On leaves and shoot => 2

1b Lateral roots with 2–4 mm long, ± spindle-shaped swellings, with some partially adventitious roots. Meloidogyne hapla

2a Malformations by aphids and spittlebugs => 3

2b Stems of young plants very much shortened, spongy, swollen, bushy clustered; petioles of basal- or stem leaves, sometimes including the under leaf blade areas galled in a similar way. Ditylenchus dipsaci

3a Malformations by aphids => 4

3b Leaves on the stunted and ± bent stem nest-like converging; curled and dark green close to the froth-covered nymph. Philaenus spumarius

4a Malformation, curling and curving of apical young leaves, caused by yellowish or greenish aphids => 5

4b Similar malformations caused by black aphids. Aphis fabae

5a Malformations by yellowish to bright green aphids lacking segmentally arranged brown dots on the dorsal surface. Brachycaudus helichrysi

5b Adult apterous aphids yellowish, possessing segmentally arranged brown dots on the dorsal surface. Myzus ornatus

1a On stems or leaves => 2

1b Centre of umbel- or partial umbel stalk swollen ± club-shaped or globular; sometimes ± spindle-shaped galls on stalks close to branching points. Containing a single orange-yellow to red larva. Lasioptera carophila

2a Malformations mainly on leaves => 3

2b Stem of young plants below the attachment of petiole swollen, barrel-shaped, also partially distorted. Complete plant stunted. Leaves ± curled and rolled. Containing a white larva. Unidentified gall midge

3a Leaves distorted or rolled inwards, ± curled => 4

3b Leaf rachis and -stalk, also stem, with, ± distinctly swollen, oblong-oval, yellowish bulges, up to about 4 mm long bearing spermogonia and brown sori of 1-celled uredinia. Puccinia nitida

4a Malformations caused by aphids => 5

4b Stem of developing plants locally stunted, sometimes distorted; leaves clustered, their tips ± nest-like converging downwards, partially curved. Infected umbels variously stunted and distorted; flowers ± disfigured. Containing a froth-covered nymph. Philaenus spumarius

4c Leaves on the underside with a white fungal down of erect conidiophores that apically bear a few short branches, each one ending in a conidium. Plasmopara anethi

5a Younger leaves variously distorted. Tips curled. Aphid black. Aphis fabae

5b Similar galls caused by green aphids with “double” cauda.
Cavariella aegopodii and/or C. pastinacae

1a On inflorescences, florets or fruits => 6

1b On leaves, stems or stalks of ± undeveloped panicles => 2

2a Several internodes of the initially elongate culm occupied by extensive patches of smut. Also on possible primordia of panicles; sometimes on leaves => 5

2b Malformations caused by animal parasites => 3

3a Culm with elongate spindle-shaped swellings => 4

3b Inner side of leaf sheaths covering parts of culm, or undeveloped stalks of panicles and occasionally even the glumes, often with long expanded rows or crusts of blister-like, at first white, then dark brown tuberculi. S. capillata: Steneotarsonemus graminis

3c In similar galls on S. capillata, pennata: Steneotarsonemus canestrinii

4a Culm above the 3th or 4th node with oblong, weak swelling. Pith containing a single larva. S. capillata: Tetramesa aciculata

4b Elongate spindle-shaped, weak swelling on culm of S. pennata. Containing a single larva. Tetramesa sp.

4c On S. capensis: Tetramesa stipae

5a Culms and possibly stalks of inflorescences with expanded blackish patches of smut on all sides. S. capillata, pennata: Sphacelotheca valesiaca

5b Similar infestation. Spores smaller, 4–6 x 3–5µ, reddish-brown, glabrous. S. capillata, dasyphylla, eriocaulis, pennata, pulcherrima: Tranzscheliella minima

6a Midrib of spikelets abnormally elongated, with swellings up to about 10 mm long, spindle-shaped, occasionally 2- or 3-winged, grain-like, sometimes ± curved. Containing a single larva. S. borysthenica, eriocaulis subsp. austriaca, pennata: Tetramesa scheppigi

6b Glumes and flower parts coalesced, transformed into a 7–10 mm long, elongate spindle-shaped, fruit-like gall. Containing a single larva. S. capillata, parviflora: Tetramesa cylindrica

6c Spikelet swollen, with lateral exit hole. S. capillata, parviflora: Tetramesa cylindrica

1a On parts above ground => 2

1b Roots with nodular to slender spindle-shaped swellings, bearing some side roots. S. arvensis: Meloidogyne hapla

1c Roots inside with giant cells, outwardly hardly changed or with excessive development of side roots above the infestation site. S. arvensis: Heterodera schachtii

2a Malformations of expanded parts of plant => 3

2b Local, rotund- to oblong-oval pads, sometimes resulting in distortions, up to about 5 mm long, occasionally slightly thickened, often yellow-margined, soon covered with 2-celled brown telia.  S. arvensis, morisonii, pentandra: Puccinia arenariae

3a Malformations caused by fungi which fruit at surface => 6

3b Malformations caused by animals => 4

4a Parasites live at surface of malformations => 5

4b Young plants completely stunted. Stem severely stunted, especially spongy, swollen at base. Basal- and gall-bearing leaves similarly disfigured. Containing many eelworms. S. arvensis, pentandra, morisonii: Ditylenchus dipsaci

5a Stem terminally stunted; organs clustered, with reduced and bent leaves and partially also with stunted, disfigured flower buds; flowers a little opened, ± greened and leafy. S. arvensis, pentandra: Inducer unknown – ? gall mite

5b Gall-like twisting, bending or S-shaped or right-angled distortion of ± discoloured leaves. S. arvensis: Taeniothrips atratus

6a Internodes of strongly infected young plants shortened, slightly thickened, sometimes curved. Leaf whorls accumulated; leaves stunted, pale green, slightly swollen as result of defective differentiation of tissue. The usually many diseased flower buds ± bloated, globular. All diseased parts soon covered with a loose down of branched conidiophores, partially containing oospores. S. arvensis: Peronospora obovata

6b Similar malformations on S. morisonii, pentandra: Peronospora vernalis

1a On stalks of umbels, flowers or fruits => 6

1b On leaves => 2

2a Localised or extensive malformations caused by animal parasites => 5

2b Small wart-shaped or larger spindle-shaped galls caused by fungi => 3

3a Galls mainly wart-shaped; spores inside host tissue => 4

3b Leaf veins, -midrib or -stalk spindle-shaped, swollen, galls usually conspicuous, sometimes ± curved, often with yellowish margins; bearing dark brown spores. Puccinia angelicae

4a Galls less than 1 mm across, multi-cellular, wart-shaped, ± golden-yellow; usually many on basal leaves, on stalks, midrib as well as on stems; sometimes coalescing into crusts or ridges. In central nutritive cell an up to 180 µm large perennial (“dauer”) sporangium. Synchytrium aureum

4b Galls similar, usually larger, ± black-brown; often clustered into densely situated groups on ± curved leaf veins, -axis or -stalk. Nutritive cells with several, ± rotund, 20–35 x 15–30 µm large perennial (“dauer”) spores. Physoderma vagans

5a Leaf blades and tips of leaflets on the often stunted midrib folded over the midrib or otherwise distorted; ± discoloured and thickened. Containing several yellowish, terminally ± reddened larvae. Jaapiella dittrichi

5b Leaf blade curved; often with curled side leaflets ± clustered, nest-like. Philaenus spumarius

6a On flowers or fruits => 7

6b Centre of (partial) umbel or stalk of umbel ± swollen, club-shaped. Inner wall covered with mycelium. Containing a red larva. Lasioptera carophila

7a Flower bud unopened, swollen to a globular or obovate gall. Unidentified gall midge

7b Fruit disfigured into a bladder-like swollen, often reddened, thin-walled gall, protruding above the partial umbel. Containing 1 (–3) orange-red larvae. Kiefferia pericarpiicola

1a On parts above ground => 2

1b Roots with nodular swellings. R. minor, serotinus: Meloidogyne hapla

2a On shoot tips, stems or leaves => 4

2b On flowers => 3

3a Flowers transformed into white-woolly, felt-like, succulent masses. Containing many larvae. R. alectorolophus, angustifolius, crista-galli, minor: Rhopalomyia cristaegalli

3b Flowers unopened or half opened. Calyx normal. Corolla poorly developed, reduced, greenish. Stamens and ovaries ± reduced. R. angustifolius: Taeniothrips atratus

4a On stems and leaves => 5

4b Side shoots terminally stunted. Younger leaves clustered, stunted, folded upwards, sometimes ± distorted, transformed into a bud-like to loose tuft-like gall, about 5–8 mm long. Between the mainly basally thickened leaf blades live yellowish-white larvae. R. angustifolius, serotinus: Macrolabis sp.

5a Malformations with erinea, consisting of hairs or conidiophores, on underside of leaves and occasionally also on stems => 8

5b Curling of leaf or swelling of stem => 6

6a Curling of several, usually terminal leaves => 7

6b Shoot axis sponge-like thickened to varied extent, ± curved. More strongly infected plants conspicuously stunted. R. angustifolius: Ditylenchus dipsaci

7a Shoot tip stunted, sometimes curved to one side. Leaves shortened, deflected, locally strongly curled and deep green. R. alectorophus, angustifolius, minor: Philaenus spumarius

7b Tips of vegetative shoots ± stunted. Leaves clustered, slightly curled and deflected. Infected inflorescences with slightly disfigured bracts and ± lacerate flowers. R. alectorolophus, angustifolius: Brachycaudus helichrysi

8a Completely diseased shoots develop faster than healthy ones, internodes thinner and longer, leaves paler, narrowed, appearing arched by deflection of margins. On the leaf underside, usually of the complete leaf blade, a very dense layer of branched conidiophores develops; usually absent from stem parts. R. alectorolophus, alpinus, angustifolius, glacialis, minor, serotinus: Plasmopara densa

8b Underside of the leaves with a greyish purple fungal down, consisting of erect, distally repeatedly dichotomously branched conidiophores. The conidia are elliptic. The host plant does not become disfigured. R. alectorolophus, angustifolius, serotinus: Peronospora pocutica

8c Leaf underside completely or partially with white floccose pubescent pads. Hairs branched or ± club-shaped. Erinea also occurring on stems. R. angustifolius: Unidentified gall mite

1a On parts above ground => 2

1b Roots with nodular swellings. P. tuberosa: Meloidogyne hapla

2a Leaf blades, stalks or stems with fruiting bodies of rust fungi or leaf blades with erinea => 9

2b Galls caused by insect larvae => 3

3a Galls on vegetative parts => 4

3b Galls caused on inflorescences and flowers. Flower heads contain gall wasp larvae. P. tuberosa: Aulacidea dyakonchukae

= As causer of flower galls, one more gall wasp has been described for P. tuberosa, namely Vetustia investigata

= The gall wasp Panteliella bicolor causes on P. tuberosa outwardly inconspicuously disfigured stems

4a Leaf galls => 6

4b Stem galls caused by cynipid larvae => 5

5a The empty inside of the stem is filled up with monolocular, thin-walled, white, rounded galls, up to 2 mm in diameter. P. tuberosa: Aulacidea phlomica

5b Similar stem gall without externally visible malformation. P. tuberosa: Phanacis phlomidis

6a Leaf galls contain gall midge larvae lacking conspicuous mouth parts => 8

6b Leaf galls contain gall wasp larvae with conspicuous mandibles => 7

7a Leaf blade on upper side with globular, 2–3.5 mm long galls; covered with long, white hairs; on underside conspicuous as small tuft. Containing a single larva. P. tuberosa: Panteliella fedtschenkoi

7b Veins with yellow to brown, spindle-shaped, 1–3 mm long swellings; two larval chambers per gall each containing a single larva. P. tuberosa: Panteliella sp.

8a Subglobular gall, 3–5 mm across, protruding equally on both sides of leaf blade, often close to margin, which is incised; sometimes on petiole, rarely on stem. One-chambered, thin walled. P. cretica, fruticosa, tuberosa: Asphondylia phlomidis

8b Flat irregular pustules on leaves, 3-4 mm in diameter, on the upperside slightly greener than the remaining part of the leaf, on the lower side of the leaf with a slightly hypertrophied epidermis and a partly swollen vein; inside each gall is a chamber where two to four larvae develop together. Usually four to six galls develop on one leaf but up to sixty galls were found on one leaf. In such cases the galls are joined, forming a large irregular pustule with several separated chambers. Larvae pupate in galls, each larva in a white cocoon. P. fruticosa: Phlomidiomyia pustularis

9a Galls with fruiting bodies of fungi on surface => 10

9b Leaf underside with erinea, infestations ± arched. P. tuberosa: Unidentified gall mite

= Similar galls, caused by unidentified gall mites, have been described for P. samia and P. herba-venti subsp. pungens

= The gall mite Aceria onychia causes abnormally hairy disfigured parts on Phlomis fruticosa, tuberosa

10a Up to 10 mm broad, yellow, rotund sori, protruding on underside bearing aecia, on upperside ± depressed pads with spermogonia or ± elongated bulges on main venation, on petioles and young stems. P. tuberosa: Puccinia stipina

10b Aecia on underside, especially on expanded parts or on complete leaf blade; sori occasionally also on petioles and stems, weakly disfiguring the infected organs. Phlomis spp.: Puccinia phlomidis

1a On parts of flowering- or fruiting inflorescences => 6

1b On stems and leaves => 2

2a Expanded malformations of variable shape => 4

2b Oval or spindle-shaped galls on stems, petioles or leaf veins => 3

3a Small galls on root collar or stem base or leaves of young plants, basally distinctly broadened and swollen. Containing a single larva. Calosirus terminatus

3b Spindle-shaped, sometimes coalescing, usually only weak and slightly expanded bulges on petioles, midrib, main veins and young stems. Puccinia nitida

4a Malformations mainly of leaf blades => 5

4b Petioles, midrib, sometimes also the basal parts of leaflets of severely stunted young plants are variously disfigured, swollen and spongy. Ditylenchus dipsaci

5a Leaf midrib ± shortened and curved, with clustered, curled, deflected leaflets. Philaenus spumarius

5b The tips of leaflets, usually of many severely stunted and disfigured leaves, are deflected and sometimes swollen and tuberculate. Trioza apicalis

5c Malformation caused by aphid. Upper leaves curled, lower leaves atrophied; leaf blade sometimes arched downwards and curled on upperside. Hyadaphis foeniculi

6a Centre of umbel or stalk of umbel ± swollen, club-shaped. Inner wall covered with mycelium. Containing a red larva. Lasioptera carophila

6b Fruit strongly inflated, bladder-like; galls ± reddened, protruding above the umbel; containing a single orange-red larva. Kiefferia pericarpiicola

1a On parts above ground => 2

1b Roots with nodular swellings. O. stricta: Meloidogyne hapla

2a On vegetative organs => 4

2b On flowers and fruits => 3

3a Flowers greened, ovaries elongated. O. acetosella, articulata, corniculata, stricta: Aceria oxalidis

3b Anthers and ovaries slightly swollen, later on containing reddish-brown spores. Diseased capsules sterile. Infestation not distinct before dusting of spores. O. fontana, stricta; not on O. corniculata: Thecaphora oxalidis

4a Malformations extended over several organs => 6

4b Galls localised => 5

5a Less than 1 mm long, sometimes joined, yellow many-celled warts on basal leaf- and stem parts. O. stricta: Synchytrium aureum

5b Slightly thickened cushions on leaves and petioles, with distinctly arched, cup-shaped aecia. ~, in NW-Eu on O. corniculata, fontana, stricta: Puccinia sorghi

6a Leaflets stunted, shorter stalked. Leaf blade rolled inwards, ± folded and twisted, finely wrinkled. O. acetosella, articulata, corniculata, stricta: Aceria oxalidis

6b Plant stunted, variously disfigured. Oxalis spp.: Aphis fabae

1a On parts above ground => 2

1b Roots with small, nodular or spindle-shaped swellings. O. verna: Meloidogyne hapla

= Cysts of a Heterodera species may occur on this host

2a On vegetative parts => 3

2b Ovaries irregularly swollen, containing a yellow larva. O. verna: Unidentified gall midge

3a Single galls wart-shaped, caused by fungi fruiting inside the host cells => 6

3b Malformations more expanded => 4

4a Malformations caused by fungi, fruiting at surface or sporulating after rupturing of bulges => 5

4b Spindle-shaped or irregularly expanded, spongy, pale-green swellings on stems and leaf veins of plants which are severely stunted. Odontites spp.: Ditylenchus dipsaci

5a Systemically infected plants or shoots developing faster, rigidly erect. Leaves pale-green, narrowed, curved downwards at margin, arched; soon covered with a dense white down of branched conidiophores. O. litoralis, vulgaris: Plasmopara densa

5b Stem with thinner or thicker quill-like swellings, up to several cm long, blue-grey, at first closed, later on rupturing and dusty. Infestation sometimes as bulge-shaped sori encroaching onto leaves. O. lutea: Urocystis schizocaulon

6a Wart-shaped, multi-cellular galls on leaves and stems, less than 1 mm across, occasionally coalescing; nutritive cells with golden-yellow perennial sorus. O. verna: Synchytrium aureum

6b Complete plant disfigured. Shoot axis and leaves with rotund red warts, usually gregarious, up to 1 mm across. Perennial spores inside a single (rarely in 2–3) enlarged parenchyma cells. O. verna, vulgaris: Physoderma negeri

1a On vegetative plant parts => 3

1b In inflorescences or single flowers => 2

2a On inflorescence stalks or spikes. Inflorescence partially ± severely stunted and greened or bleached. Aceria tenuis

2b Single ovaries of a panicle strongly swollen and transformed into an oval or oblong smut body, up to 10 mm long; inside develop brown-black spore masses, at first clotted, later on crumbling and forming dust of spores. Neovossia moliniae

3a On above-ground parts => 4

3b Root hairs distinctly swollen; inducer inside the hair. Sorosphaerula radicalis

4a On culms => 5

4b Leaf sheath at base swollen, bellied out. Containing a large, whitish larva, almost 5 mm long. Unidentified gall midge

5a Culm with spindle-shaped or bellied swelling => 6

5b Shoot axis immediately above the ground below the leaf sheath with weak, slightly rimmed depression. Containing a single white larva. Mayetiola moliniae

6a Culm just above the ground swollen to bellied out, apically conically narrowed gall up to 10 mm long, which erupts from the leaf sheath. Larvae white, gregarious. Mayetiola ventricola

6b Culm weakly swollen, containing a single, orange-yellow larva almost 5 mm long. cf. Lasioptera moliniae

1a On parts above ground => 5

1b On roots => 2

2a Outside of root hardly changed, only disfigured inside or with rotund galls having central chamber => 4

2b Distinctly protruding galls, larval chamber absent => 3

3a Nodular galls, occupying all sides of root body. Lupinus spp.: Meloidogyne hapla

3b Main roots with protrusions up to about 15 mm long, broadly attached, usually many, often clumped close to root collar, coalescing, tuberculate, on perennial species even up to 50 mm wide; less often rotund or oblong-oval smaller nodules also on the adventitious roots. Lupinus spp.: Rhizobium lupini

4a Galls not recognisable from the outside; with giant cells inside. Lupinus spp.: Heterodera schachtii

4b Roots with rotund, 4–6 mm long gall with chamber containing beetle larva. L. luteus: Unknown snout beetle

5a Malformations of leaves, stems and flowers => 6

5b Pod disfigured, slightly atrophied; inner wall with mycelium. Containing a single larva. L. albus: Asphondylia lupini

6a Malformations caused by aphids => 7

6b Development of plant severely stunted; axial parts irregularly swollen, spongy. Infestation often encroaching onto stalk and venation of severely disfigured leaves. L. angustifolius: Ditylenchus dipsaci

7a Apterae are pale bluish-grey-green, dusted with white wax; body length 3.2‒5.1 mm. Alatae have a brown pterothorax. Lupinus spp.: Macrosiphum albifrons

7b Apterae and alatae black. Leaf blades distorted, also strongly curved, rolled or folded. L. angustifolius, luteus: Aphis fabae

1a On vegetative organs => 2

1b Flower buds inflated, thickened, unopened, usually normally coloured. Containing pale yellow larvae. L. vulgare: Placochela ligustri

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

2a On leaves => 5

2b On buds or axial parts => 3

3a On axial parts => 4

3b Several axillary buds, rarely the apical bud, slightly swollen, stunted, developing leaves often only scale-like. Malformation resulting in compact, ± pyramidal witches’ broom-like structures. L. ovalifolium, vulgare: Aceria loewi and/or Aculus ligustri

4a Axial parts, mainly at base, with conspicuous proliferations, up to walnut-size, soon woody, irregularly wrinkled, on surface, dark-brown. “Bacterial cancer” L. vulgare: Agrobacterium tumefaciens

4b Bark swollen, with rimmed irregular depressions, containing causer. L. ovalifolium, vulgare: Chionaspis salicis

5a Malformation of many leaves at shoot tip => 6

5b Leaf blade with rotund, yellowish-green pads, sometimes slightly swollen if on venation, bearing cups on underside. L. ovalifolium, vulgare: Puccinia obtusata

6a Axis of young shoots and stalks of young leaves shortened. Infected leaves loosely clustered. Prociphilus bumeliae

6b xis of young shoots not shortened; usually deflected from the tip, bearing many, distant, downwardly rolled or slightly curved leaves, sometimes twisted, yellow- to rust-spotted. L. ovalifolium, vulgare: Myzus ligustri

1a On parts above ground => 3

1b On roots => 2

2a Rotund- to oblong-oval nodules, about 3 mm long laterally attached on main- and side-roots. L. culinaris, nigricans: Rhizobium leguminosarum

2b Outside of roots hardly disfigured, inside containing giant cells; bearing temporarily white to dark, about poppy seed- sized egg capsules (cysts). L. culinaris, nigricans: Heterodera schachtii

3a Leaflets of many terminal leaves rolled inwards and upwards, ± bent. L. culinaris, nigricans: Aceria trifolii

3b Flower bud swollen, unopened. L. culinaris: Contarinia sp.

= Early records of Dasineura viciae and Asphondylia ervi on “lentils’” need confirmation.

c Flower bud swollen, unopened. L. culinaris: Contarinia lentis

1a On vegetative plant parts => 2

1b Capitula deformed; receptacle thickened. Unidentified tephritid fly

= Midge larvae of an undescribed Dasineura occur in capitula of Mediterranean H. alpina

2a Leaf blade or petiole with galls caused by fungi, spores of which develop on the outside, or shine through the gall surface => 5

2b Malformation of the leaf blade by animal inducers => 3

3a Localised galls => 4

3b Leaf blade deflected ± curled, locally intense green. Philaenus spumarius

4a Leaf blade with pock-like swellings, which are especially arched on the underside. Unidentified gall mite

4b Leaf blade between the veins bulging and swollen. Larvae on the underside. Trioza thomasii

5a The fruiting bodies develop on the surface of spindle-shaped galls => 6

5b Wart-shaped, less than 1 mm long galls, the ± golden yellow spores develop inside and shine through the gall surface. Synchytrium vulgatum

6a Only just protruding, orange-coloured thickenings on petioles and on the underside of leaf veins bearing densely, ± circular arrangements of aecia and with pycnidia developing on the upperside. Uromyces veratri

6b Telia in small to extended brown sori. Stronger infestation sites on leaf blades with upperside impressions and with rotund, protruding, compact pads on underside; on veins and petioles developed as ± elongated spindle-shaped, often yellow margined bulges. Puccinia conglomerata

1a On above-ground parts => 2

1b Roots with almost rotund swellings, up to 4 mm long, sometimes clustered. H. annuus: Meloidogyne hapla

= Heterodera schachtii is known from H. annuus

2a Galls on root collar or on stem. The inducers are inside the galls => 4

2b Malformations predominantly on leaves. The inducers live on the surface of the malformations => 3

3a Leaves variously curled or bulging; malformations by aphids. Helianthus spp.:

a Brachycaudus helichrysi

b Aulacorthum solani

c Aphis fabae

3b Leaf blades of young plants over extensive parts and in various ways bent downwards, curled, and dark green close to the froth-covered nymph. Helianthus spp.: Philaenus spumarius

3c Dull white spots, pustules, even crusts on underside of leaves, largely consisting of a mass of conidia. H. annuus: Pustula helianthicola

4a Up to walnut- size or extensive, rugose proliferations on root collar or the basal stem parts. H. annuus, tuberosus, etc.: Agrobacterium tumefaciens

4b Spongy swellings of various shape on stems, petioles, leaf veins of young plants. H. annuus, tuberosus: Ditylenchus dipsaci

1a On above-ground plant parts => 2

1b Nodular swellings on roots. Meloidogyne hapla

2a On parts of inflorescence or on fruits => 6

2b On vegetative parts => 3

3a Malformations caused by animal parasites => 4

3b Stalks, midrib or veins of leaves, also stalk of umbel or fruit with bulging swellings bearing spermogonia and pale-yellow aecia. Uromyces graminis

4a Rosette leaves or terminal parts of vegetative shoots variously disfigured by aphids; midrib ± stunted and distorted; tips of leaflets clustered, curved and curled => 5

4b Globular swelling of ramification of leaflet; gall inside covered with mycelium. Containing a single gall midge larva. Lasioptera carophila

4c Midrib of leaf locally severely stunted and including some side spindles strongly converging downwards, nest-like. Philaenus spumarius

5a Aphid black. Aphis fabae

5b Aphid green. Cavariella aegopodii

6a Centre of umbel or stalk of umbel ± swollen, club-shaped. Inner wall covered with mycelium. Containing a single red larva. Lasioptera carophila

6b Spindle-shaped swelling of stalk of umbel. Containing a single yellow larva. Lasioptera umbelliferarum

= Lasioptera foeniculi has been described causing fruit galls. Galls from September up to November; larvae pupate in soil, adults emerge about 10 days afterwards.

6c ruit conspicuously swollen, ± reddened, often protruding above the partial umbel. Containing a single orange-red larva. Kiefferia pericarpiicola

1a Malformations of leaves at the tips of the shoots => 3

1b Swellings of the shoot stems => 2

2a Spindle-shaped or cylindrical swelling in main- or side stem near a node or in axils of flower peduncles, about 10–15 mm long, with round opening when mature; one or several yellowish-white caterpillars with a yellow-brown head, in pith with frass. Upper stem parts stunted, often conspicuously discoloured. Adaina microdactyla

2b Stem mainly close to the ground, with differently situated and expanded, sometimes curved swelling. A scale insect in a depression. Planchonia arabidis

3a Malformations by aphids or spittlebugs => 4

3b Leaves on stunted shoot tips clustered, rolled upwards, rudiments of inflorescences stunted. All infected parts conspicuously white pubescent. Aceria eupatorii

4a Aphid malformations => 5

4b Leaf segments nest-like converging, the leaf blades curled, dark green close to the froth-covered nymph. Philaenus spumarius

5a Leaves on ± stunted shoots more or less stunted, the margins curved downwards, the leaf blade ± curled. Aphid 1.5–2 mm long, bright yellowish to yellow green, with short conical yellowish to green cauda. Brachycaudus helichrysi

5b Similar malformations by dark green aphids; siphunculi and cauda dark to black. Aphis frangulae

1a On parts above ground => 2

1b Roots with ± expanded spindle-shaped, fleshy swellings, which contain densely crowded masses of minute spores in some cells. D. incana, muralis: Plasmodiophora brassicae

2a Malformations caused by fungi fructifying at surface of gall => 6

2b Malformations caused by animals, or by fungi fructifying inside galls => 3

3a Galls localised => 4

3b Infected shoots extensively disfigured, phyllanthy; leaves shorter and broader, ± disfigured; flowers often accumulated, tuft-like, atrophied or ± greened. D. aizoides, daurica, incana, muralis, nivalis, “rupestris”: Aceria drabae

3c On the same hosts and other Draba species in similar malformations. D. aizoides, daurica: Cecidophyes borealis

4a On leaves or stem parts => 5

4b Diseased shoots slightly swollen, slightly shorter than healthy ones; young seed soon distorted and filled with yellowish- to grey-violet sori. D. aizoides, alpina, incana: Thecaphora thlaspeos

5a Galls hardly 1 mm across but conspicuous, ± golden-yellow translucent; on leaves, stalks and even bracts; often coalescing into crusts. D. aizoides: Synchytrium drabae

5b Stalk of inflorescence shortened at tip, slightly thickened, curved. D. muralis: Cause unknown – ? dipteran

6a At first glossy, porcelain-like, with mealy dusty bulges on all green parts after rupturing. D. aizoides, cuspidata, hispanica, incana, sauteri: Albugo candida

6b Infected organs, mainly the upper stem parts, variously ± bulge-like, swollen and disfigured. Draba spp.: Puccinia drabae

6a Shoots etiolated. Underside of leaves often bearing dense, rotund sori. D. cinerea, daurica: Puccinia thlaspeos

6b Leaves with pales spots. Underside with a dense white down, consisting of erect conidiophores that apically are branching several times, each branch ending in a conidium. D. muralis, nemorosa: Hyaloperonospora drabae

6a Similar malformation. D. daurica, nemorosa: Hyaloperonospora norvegica

1a Leaf blades arched and curled, caused by aphids or cercopids => 3

1b On root collar or roots => 2

2a Roots with small nodule-shaped swellings. Meloidogyne hapla

2b Conspicuous succulent, cauliflower-shaped proliferations on tubers, on root collar or stem base. Agrobacterium tumefaciens

2c Irregular proliferations of the stem base, combined with an abundant development of buds. Rhodococcus fascians

2d Extensive malformations usually accompanied by R. fascians. Aphelenchoides fragariae

3a Deformities caused by aphids => 4

3b nfected young shoots severely stunted, the leaves curved downwards, curled, dark green close to the froth-covered nymph. Philaenus spumarius

4a Aphid black. Aphis fabae

4b Aphid green. Aulacorthum solani

1a Malformations on leaves => 3

1b Malformations on stems => 2

2a Witches’ broom-like malformations with only little, often reddish leaves on sap-rich, whip-shaped shoots. C. speciosa: Inducer unknown, presumably caused by a fungus, Exoascaceae

2b Considerable cancer-like proliferations on basal stems. C. speciosa: Agrobacterium tumefaciens

3a Malformations on several terminal leaves caused by aphids => 4

3b Leaves with ± protruding bladder-like, pale-green or reddened swellings, later on withering, which at maturity are occupied by a grey-white layer of fungal asci. ? C. speciosa: Taphrina bullata

4a Leaves rolled inwards and crumpled, clustered nest-like on the ± shortened shoots => 5

4b Leaves obliquely bent downwards and ± rolled. C. japonica: Myzus persicae

5a Aphid with rather long siphunculi. Chaenomeles spp.: Aphis pomi

5b Aphid with short, thick, green siphunculi. C. japonica, speciosa: Rhopalosiphum oxyacanthae

1a On inflorescences or flowerd => 7

1b On vegetative plant parts => 2

2a Leaves with long stripes caused by smuts => 6

2b Malformations caused by animal parasites => 3

2c Whitish, at surface yellowish or brownish patches, which envelope a large area of the upper part of stem, of which further development is stunted. Node of stem rarely swollen, encircled by fungus stroma, yellowish when mature; several nodes may be affected; flowering stunted; stroma contains narrow asci and filamentous spores. Brachypodium spp.: Epichloë sylvatica

3a Localised galls on culms => 5

3b Shoot tip with tuft-like clustering of leaves or complete plant disfigured => 4

4a Especially the tips of subterranean runners with short sheath-like, tuft-like accumulated leaves. Gall up to 40 mm long and 12 mm broad. Larva white with black buccal skeleton. B. pinnatum, sylvaticum: Unidentified chloropid fly

4b Tip of above-ground shoot with spindle-shaped tuft of leaves. Inside a larva causing a severely stunted, broadened culm. B. pinnatum, sylvaticum: Tetramesa brachypodii

5a Stem closely just above a node with 10–12 mm long and 4–5 mm broad, saddle-like depression, thickened at both ends, containing a white larva. Usually ± enclosed by leaf sheaths. B. pinnatum, sylvaticum: Mayetiola hellwigi

5b Culm above one of the lower nodes with an egg-shaped swelling about wheat grain size. Containing a single larva. B. sylvaticum: Tetramesa sp.

6a Often all parts of host diseased, exceedingly leafy; initially developing faster, soon severely stunted, remaining small and sterile. Leaves with long, at first slightly arched patches of smut, then breaking open, ± fraying out the leaves, releasing a black-brown mass of spores. B. pinnatum, retusum, rupestre, sylvaticum: Tilletia olida

6b Similar stripes of smut on the leaf blades of often further developed, hardly additionally leafed plants. Spores rotund to oblong-oval, with many blunt warts. B. pinnatum, sylvaticum: Ustilago striiformis

6c Long conspicuous stripes on chlorotic leaf tissue caused by rust fungus. B. pinnatum, sylvaticum: Puccinia striiformis

7a Spikelets elongated; flowers ± greened, bleached if strongly infected. B. pinnatum: Aceria tenuis

7b lowers leafy; glumes ± enlarged, occasionally enclosed in the spikelet; the midrib bent zig-zag-like. B. pinnatum: ? Ditylenchus sp.

7c Complete plant stunted by scale insects, especially the inflorescence. B. pinnatum, retusum, rupestre, sylvaticum: Eriopeltis festucae

1a On A. officinalis => 2

1b On A. acutifolius, aphyllus. Young twigs irregularly swollen and curved, terminally with tufts of compressed leaves with broadened bases, discoloured or reddish. Overwintering buds variously abnormally hypertrophied. Containing flesh-coloured larvae: Dasineura turionum

1c Usually the whole shoot, just after budding, is transformed into a gall. Leaf scales are swollen and broadened at base. The white midge larvae are located under the swollen scales. A. acutifolius, albus, tenuifolius: Dasineura minardii

1d Fruits changed into spongy mass. A. aphyllus: Dasineura sp.

2a On above-ground parts => 3

2b Roots with nodular swellings. A. officinalis: Meloidogyne hapla

3a On vegetative parts => 4

3b Flower buds globular, perianth succulent, swollen, dark-green; not opening. Containing several white- to orange larvae. A. officinalis: Contarinia florum

4a Stunting of stems with terminal green shoots; caused by aphids => 5

4b Stem of young, pale or greened shoots crippled. Tip ± curved, crooked, dying off early. Often several yellowish-white larvae, up to 10 mm long in extended tunnels. A. officinalis: Plioreocepta poeciloptera

4c Terminally distorted and discoloured spines of young twigs transformed into swellings with broadened base. Gregarious white larvae between the spines. A. acutifolius, aphyllus, officinalis: Dasineura asparagi

5a Leaves of solitary or of several neighbouring shoot tips accumulated densely like bottle brushes, shortened, ± rounded, rigid, dark green; with colonies of grey-powdered aphids in between. A. aethiopicus, densiflorus, officinalis: Brachycorynella asparagi

5b Similar malformations; however more loosely tuft-like; leaves softer, ± downwardly deflected. Aphid black. Asparagus spp.: Aphis fabae

1a On parts above ground => 2

1b On roots or on root collar. Nodular swellings on roots. Galls partially with side roots. Antirrhinum spp.: Meloidogyne hapla

2a On leaves => 3

2b Swelling of stem. A. latifolium, majus: Mesoscyonyx sicardi

2c Capsule slightly swollen and disfigured; a single or several beetle larvae inside. A. majus: Rhinusa antirrhini and/or Rhinusa neta

3a Leaves ± curled and margins deflected; bearing aphids on underside => 4

3b Leaves stunted on shortened shoot tips, pale green, deflected over tip and margins, brittle, appearing slightly thickened; with down of branched conidiophores on underside. A. hispanicum, majus, sempervirens: Peronospora antirrhini

4a Leaf blades strongly curled. Antirrhinum spp.: Aulacorthum solani

4b Leaf blades spoon-like arched, curled, ± discoloured, bearing aphids on underside. A. barrelieri: Myzus persicae

1a On buds and shoot axis => 6

1b On leaves (or occasionally fruits for fungi) => 2

2a Galls ± bulge-shaped, usually yellowish, with patches of spores on upper side => 5

2b Malformations caused by animals => 3

3a Galled leaves not conspicuously clustered => 4

3b Terminal leaves clustered. A. ovalis: Dysaphis parasorbi

3c Leaves terminal on severely stunted shoots mainly on tip rolled downwards, usually densely clustered. Amelanchier spp.: Aphis pomi

3d Shoots with several leaves ± curved and variously obliquely downwardly curved along the midrib. Amelanchier spp.: Rhopalosiphum oxyacanthae

4a Leaf blade ± pod-like folded upwards along the midrib, thickened in the middle. A. ovalis: Unidentified gall midge

4b Leaf blade with many pocks, protruding on both sides of leaf. A. ovalis: Eriophyes aroniae

5a Leaves, sometimes also young shoots, with yellow, later on reddened in the middle, swollen, aecia bearing pads. Peridium cylindrical, 2–3 mm long, open above, deeply thread-like lacerate; lateral walls of cells with many tubercles of various shape and size. Amelanchier spp.: Gymnosporangium clavariiforme

5b Galls similar. Peridium usually oblong-cornicular, 3–4 mm long, conical apex, at first closed, then opening, slightly or not lacerate at margin; lateral walls of cells ± densely tuberculate, or very short, with obliquely running ridges. A. ovalis, asiatica: Gymnosporangium cornutum

6a On shoot axial parts => 7

6b Buds swollen, not opening; scales enlarged, thickened, densely white pubescent. A. ovalis: Eriophyes amelancheus

7a Bark of stems or branches with cracked cancer-like proliferations; with white powdered aphids in cracks. Amelanchier spp.: Eriosoma lanigerum

7b Major branches with spindle-shaped swellings. A. ovalis: Viscum album

1a On parts above ground => 3

1b On roots => 2

2a Side roots with mainly rounded, nodular swellings. Althaea officinalis; Alcea rosea & var. nigra: Meloidogyne hapla

2b Main root thickened, beet-like. Central chamber contains a single larva. Althaea hirsuta: Unidentified coleopteran

3a Malformations caused by animal parasites => 4

3b Leaves and all other green organs, as well as stem, epicalyx and even young ovaries, with rotund, 1‒2 mm broad, cushion-shaped swellings, soon bearing at first yellow-red, later on brown telia. Telia germinating immediately, giving them a whitish-powdery appearance. Alcea spp.; Althaea spp.: Puccinia malvacearum

4a Malformations lacking conspicuous additional pubescence => 5

4b Leaves on Althaea officinalis with localised erinea. Unidentified gall mit

5a Malformation of leaf blades => 6

5b A single mericarp contains a beetle; there also pupation takes place. Infected flowers fade prematurely. Alcea dissecta, rosea, setosa: Rhopalapion longirostre

6a Leaf blades, usually of many terminal leaves, on ± stunted shoots loosely arched downwards and ± curled. Alcea biennis, nudiflora, rosea; Althaea officinalis: Aphis althaeae

6b Leaf blade ± strongly wrinkled, margins deflected. Sometimes the flower buds are also disfigured. Contain pale green aphids with siphunculi half as long or equalling cauda. Alcea rosea, Althaea officinalis, cannabina: Acyrthosiphon malvae

6c Venation close to infestation stunted and deflected; neighbouring leaf blade part curled, deep green, rolled- or curved downwards, nest-like. Contains a froth-covered nymph. Alcea spp.; Althaea spp.: Philaenus spumarius

1a On vegetative organs => 2

1b Anthers in rarely disfigured flowers temporarily swollen; later filled with black-violet spores. Microbotryum violaceum

2a Malformations with surface fruiting fungi, at least temporarily => 5

2b Malformations caused by animals => 3

3a Malformations on stems or leaves of ± developed plants => 4

3b Young plants severely stunted; especially the basal parts swollen, spongy. Swellings pale green, undulate at surface. Ditylenchus dipsaci

4a Stem with localised swellings. Unidentified lepidopteran

4b Tuft-like accumulation of basally strongly pubescent leaves. Inducer unknown

4c Stem stunted locally, one or two neighbouring leaves strongly rolled over their tips; close to the froth-covered nymph undulate, deep-green. Philaenus spumarius

5a Leaves on underside with rotund, ring-shaped or sometimes oblong compact crusts of coalescing sori on slightly swollen bulges; at first bearing pale, later on with black-brown telia. Bulges also developing on calyx teeth and stems. Puccinia arenariae

5b Leaves and stems with yellowish, ± swollen spots; diseased leaf blades, and even the corolla, often characteristically curled; sori ± grey frosted when asci are mature. Taphrina githaginis

1a On stems or leaves => 2

1b Centre of umbel or stalk of umbel ± swollen, club-shaped. Inner wall covered with mycelium. Contains a red larva. Lasioptera carophila

2a Large parts of plant disfigured => 4

2b Stem or leaves with localised galls => 3

3a Stem, and stalks of partial umbels with lateral rounded swellings, 2–3 mm long; with an irregular larval chamber inside. Unidentified beetle

3b Minor, weak bulge-like archings on leaf veins, rachis, -stalk or stem; soon bearing spermogonia and primary uredinia. Puccinia nitida

4a Curled leaf blades caused by aphids or cercopids => 5

4b Younger plants severely stunted. Leaf axis and possibly basal stem parts distinctly shortened, spongy, pale-green, with undulate-wrinkled surface. Ditylenchus dipsaci

5a Larger composite leaves ± nest-like or bell-shaped converged downwards; strongly curled, deep-green close to the froth-covered nymph. On developing plants often several leaves on locally markedly shortened stems are similarly disfigured. Philaenus spumarius

5b Leaves remaining small, rolled, closely accumulated, dark-green discoloured; bearing green aphids. Cavariella aegopodii and/or C. pastinacae

= Also living in summer on several umbellifers is the aphid Hyadaphis foeniculi which might be responsible for the malformations

5c Several leaves stunted and curled; tips deflected. Leaf blades ± knobby swollen, not discoloured. On underside several flat froth-covered nymphs surrounded by a border of white wax hairs. Trioza apicalis

1a On vegetative parts, on flowers or inflorescences => 2

1b Fruit strongly swollen, bladder-like. Containing a deep orange-red larva. S. carvifolia: Kiefferia pericarpiicola

2a Expanded or locally narrowly confined malformations caused by animal inducers => 5

2b Bulge-like swellings on leaf venation, -stalk or young stem parts, caused by fungi => 3

3a Conspicuous, often ± curved swellings, bearing uredinia or telia => 4

3b Bulges of various size on ± curved leaf blades and axis, bearing yellowish spermogonia and aecia. S. carvifolia: Puccinia bistortae

3c Vitreous bulges. S. carvifolia: Protomyces macrosporus

3d Leaves on the underside a white fungal down of erect conidiophores that apically bear a few short branches, each one ending in an ovoid conidium. S. carvifolia: Plasmopara selini

4a Fungus develops only 3-celled teliospores bearing distal spines. S. carvifolia: Nyssopsora echinata

4b Sometimes up to 30 mm long sori coalescing into ± protruding bulges on stems are induced by a mycelium developing primary uredinia and spermogonia. Teliospores 2-celled. S. carvifolia: Puccinia selini-carvifoliae

5a Malformations caused by aphids, spittlebugs or mites => 6

5b Centre of umbel or stalk of umbel ± swollen, club-shaped. Inner wall covered with mycelium. Containing a red larva. S. carvifolia: Lasioptera carophila

6a Malformations caused by aphids or spittlebugs => 7

6b Complete plant variously stunted. Young stems ± distorted. Umbels stunted; flowers ± greened or leafy. S. carvifolia, dubium, silaifolium: Aceria peucedani

7a Leaflets converging, axis ± deflected, leaf blades curled, wrinkled and deep green at site of infestation. S. carvifolia: Philaenus spumarius

7b Stalks of umbel, sometimes in the same umbel, variously shortened. Flowers clustered; the severely stunted organs sometimes variously greened or also leafy. S. carvifolia: Unidentified aphid

1a On leaves or flowers => 2

1b Conspicuous, at first whitish, succulent, later on strongly browned, woody proliferations on root collar. Rhododendron spp.: Agrobacterium tumefaciens

2a On shoot tips or leaves => 3

2b The flowers are irregularly ± double. R. ferrugineum, hirsutum, intermedium: Aceria alpestris

3a Malformations of leaf blades => 5

3b Malformations of shoot tips => 4

4a Conspicuous bud-like tuft of leaves on shoot tip. R. ferrugineum: Dasineura rhododendri

4b Terminal buds crippled; often increased in number. Leaves reduced and disfigured. Buds dying prematurely. ‘Shoot tip mite’. R. simsii: Tarsonemus sp.

5a Leaf blade with rolls of margin or pouch-like to spherical galls => 6

5b Leaf blade otherwise weakly disfigured. R. ferrugineum, hirsutum: Cacopsylla rhododendri

6a Roll of leaf margin => 8/p>

6b Succulent galls on leaf blade => 7

7a Leaf blade largely or completely thickened, pale-green, later on densely chalk-white frosted, especially on underside. Sometimes several, almost rosette-like clustered leaves terminally on severely stunted, thickened, young shoots similarly disfigured; galls sometimes also on calyx leaves and even on corolla. “Earlobe disease”. R. caucasicum, indicum, nudiflorum, obtusum: Exobasidium japonicum

7b Up to about cherry-size, succulent, yellowish or often one-sided reddened, later on white frosted, often almost globular galls on leaves, sporadically even on flower parts, as well, sometimes, ± clustered, raceme-like, on shoot tips. R. ferrugineum, hirsutum, x intermedium: Exobasidium rhododendri

7c Galls succulent red-orange. R. luteum, ponticum: Exobasidium horváthianum

8a Leaves on unshortened shoot tip usually narrowly rolled upwards over all their length, lighter; with small 1-celled hairs on both sides. R. ferrugineum, hirsutum, intermedium: Aceria alpestris

8b Leaf margin rolled downwards, ± curled and crippled. R. indicum, molle: Phyllocoptes azaleae

8c Mites living in buds and free on the underside of the leaves. They can cause bronzing and rusting of the young leaves, downwards rolling of the leaf margins and eventually stunting; in nurseries. R. atlanticum, japonicum: Aculus atlantazaleae

8d Rolling of the leaf margin. R. ferrugineum: Aculus thomasi

1a On roots or on root collar => 5

1b On parts above ground => 2

2a Malformations on vegetative parts => 3

2b nflorescence ± half-globularly clustered as result of shortening of axis. Development of flowers stunted, usually unopened. P. paniculata: Unidentified dipteran

3a Causers on outside of malformations => 4

3b Single or all shoots of a plant strongly shortened by eelworms living inside the tissue, variously swollen, leaves ± curved and curled, partially strongly reduced, narrowed, almost thread-like. Shoot tuft- to broom-like. P. amoena, paniculata, etc.: Ditylenchus dipsaci

4a Leaves strongly rolled and curled over their tips, locally deep green. Phlox spp.: Philaenus spumarius

4b Malformations of leaf blades caused by aphids. P. paniculata: Unidentified aphid

5a On root collar => 6

5b Roots with small swellings bearing several side roots. P. paniculata, etc.: Meloidogyne hapla

6a Considerable proliferations with only small partitioned surface. P. paniculata: Agrobacterium tumefaciens

6b Clustering of crook-backed branched, markedly shortened, fleshy thickened shoots. P. paniculata, etc.: Rhodococcus fascians

1a On vegetative parts => 2

1b Corolla unopened, lower part thickened, leather-like, colourless to brown, up to 4 mm long, 2 mm broad; not joined with the slightly swollen calyx. Containing a single larva. O. vulgare: Asphondylia hornigi

2a Malformations of undefined shape on several organs, mainly at tips of shoots => 4

2b Galls on shoot tips, as well as lateral buds or on axial parts of shoots => 3

3a Shoot axis with spindle-shaped or oblong, bulging, multi-chambered swelling. O. vulgare: Thamnurgus kaltenbachii

3b Small, unilateral stem galls, containing a weevil larva or its pupa. O. vulgare: Squamapion origani

3c Shoot tip or lateral buds transformed into oval tufts of leaves, up to 15 mm long and 10 mm broad, greenish, compact. Leaves broadened, thickened, arched, on upperside often with long white hairs. Containing several red larvae. O. compactum, vulgare & subsp. virens: Blastomyia origani

4a Malformations caused by animals => 5

4b Large parts of plant or only single shoots transformed into little, rigid, erect witches’ brooms as result of excessive branching and leafiness. Diseased shoot axis distinctly narrowed; leaves conspicuously reduced. Brownish sori soon develop on axial parts. O. vulgare: Puccinia thymi

4c Leaf blades, especially of young leaves at shoot tip, with thick purple patches bearing spermogonia and aecia, followed by uredinia and telia. O. vulgare & subsp. virens: Puccinia menthae

5a Malformations lacking excessive pubescence => 6

5b Tip of non-flowering or flowering shoots disfigured; developing ± dense masses of felt-like pubescent leaves, and leafy or greened flowers. O. majorana, vulgare: Aceria labiatiflorae

6a Galls caused by aphids => 8

6b Galls caused by gall midges or spittlebugs => 7

7a Roll of leaf margin caused by gall midge larvae. O. vulgare: Unidentified gall midge

7b Shoot axis buckled, bent locally, bearing several deflected, curled, partially deep green leaves. O. vulgare: Philaenus spumarius

8a Several to many leaves at the end of shoots apically increasingly stunted, laterally ± narrowly rolled, curled. Plants often largely disfigured. O. majorana, vulgare & subspp. gracile + virens + viridulum: Aphis origani

8b Leaves curled. O. vulgare: Aphis nepetae

8c Malformations caused by aphids on terminal vegetative- or developing flowering shoots. O. majorana: Myzus ornatus

1a On parts above ground => 2

1b Roots with nodular swellings. N. cataria: Meloidogyne hapla

2a On flowers or fruits => 6

2b On vegetative organs => 3

3a On leaves => 5

3b On shoot tips or axial parts => 4

4a Tip of shoot ± disfigured. Youngest leaves erect, folded together, yellowish with cartilaginously rolled margin. Containing orange-yellow larvae. N. cataria: Wachtliella stachydis

= Midge described from Stachys, on which it also induces inflorescence galls. Identity of the midge on Nepeta is doubtful

4b Shoot axis with multi-chambered, elongate and bulging swellings, up to 30 mm long. In each chamber is a single, curved, lemon-yellow beetle larva. N. cataria: Squamapion vicinum

5a Leaves curled or loosely rolled. N. cataria, nepetella & subsp. aragonensis, nuda: Aphis nepetae

5b Leaves folded or rolled. N. cataria: Aulacorthum solani

6a Gall on flowers => 7

6b One mericarp transformed into a ± globular gall, up to 5 mm long, the three remaining ones aborted. Calyx enlarged, cup- or bell-shaped, later on rupturing over its length. Corolla atrophied. Containing a single larva. N. nuda, also N. beltranii, cataria, grandiflora, latifolia, nuda & subsp. albiflora, ucranica & subsp. parviflora: Liposthenes kerneri

7a Flowers swollen at base, disfigured, often unopened. Containing red larvae. N. cataria: Jaapiella catariae

7b Flower buds swollen, egg-shaped, dark-green, unopened. N. nuda: Asphondylia sp.

1a On parts above ground => 2

1b Root with nodular swellings. M. sylvestris: Meloidogyne hapla

2a Malformations on vegetative parts, only sometimes encroaching onto primordia of inflorescences => 3

2b Single mericarps between the other hardly changed mericarps conspicuously swollen, up to twice the normal size. Containing a curved beetle larva. M. alcea, multiflora, neglecta, pusilla, subovata, sylvestris, trimestris: Malvapion malvae

3a Expanded malformations of leaves caused by animals => 5

3b Localised galls on stems or small pads bearing sori on all green organs => 4

4a Leaf blades, -stalks, axial parts of shoots, even calyx and green fruits with many small, rotund or oblong, yellowish, eventually red- to dark brown spores bearing bulges. Malva spp.: Puccinia malvacearum

4b Plant ± atrophied; stem thickened, distorted; inner wall browned. M. moschata: Inducer unknown

5a Malformations with abnormal pubescence; caused by mites => 8

5b Malformations lacking abnormal pubescence; caused by aphids, scale insects or spittlebugs => 6

6a Malformations contain aphids => 7

6b Shoot axis often with several oval to spindle-shaped swellings with centrally rimmed depressions which contain a flat froth-covered nymph. M. thuringiaca: Planchonia arabidis

6c eaves curled, deflected, nest-like; often deep green at infestation site. Infestation on erect young plants usually similarly involving several leaves. Containing a froth-covered nymph. Malva spp.: Philaenus spumarius