Dichotomous table for gallers on Silene

by Hans Roskam

1a On parts above ground => 3

1b On subterranean parts => 2

2a Roots with 2–5 mm long, cylindrical galls, sporadically bearing side roots. S. atropurpurea, coeli-rosa, gallica, vulgaris: Meloidogyne hapla

2b Subterranean buds swollen, up to 4 mm across. Leaves clustered, tuft-like, succulent, whitish. Containing a single white larva. S. cucubalus, nutans, vulgaris: Dasineura subterranea

3a On inflorescences or flowers => 30

3b On stems, shoot tips, axillary buds or leaves => 4

4a Malformations on leaves, shoot tips, axillary buds or upper stem parts => 8

4b Basal rosettes or basal shoot organs largely disfigured, or leaf blades of rosette leaves with small yellowish warts => 5

5a Malformations caused by animals => 6

5b Leaf blades of rosette leaves with many warts, less than 1 mm long, multicellular, yellowish, occasionally coalescing; also on basal stem parts. Silene flos-cuculi: Synchytrium aureum

6a Malformations of basal leaves or leaf blades => 7

6b Young plants severely stunted. Stems stunted, spongy, swollen, inserted leaves variously disfigured. Silene spp.: Ditylenchus dipsaci

7a Basal leaves stunted. Leaves with their base spindle-shaped, converging; containing a green caterpillar, distinguished by its dark red first segment. It feeds on bast and cortex of young stems, which appear slightly thickened because of callus formation. S. nutans: Caryocolum sp.

7b Leaf blades of basal leaves in longitudinal direction knee-like bent, almost at right-angles, at any point. Breaking point close to midrib succulent, swollen, usually yellow-green, sometimes reddish. S. viscaria: Planchonia arabidis

8a On shoot tips, side shoots, and -buds or on leaves => 14

8b On axial parts of shoot => 9

9a Malformation caused by larvae with a distinct head capsule => 10

9b Swellings spongy; very variable in shape and expansion; with undulate or wrinkled surface. Silene spp.: Ditylenchus dipsaci

10a Malformations caused by a pith-tunneling caterpillar => 11

10b Stem with conspicuous ± spindle-shaped or cylindrical, tough-walled, glabrous swellings; caused by beetle larvae. Galls about 10 mm long and 5 mm thick, spindle-shaped or cylindrical; single or with a few together. Containing a single larva. Silene spp.: Sibinia femoralis

11a Galls very conspicuous on all sides, more than 15 mm long => 12

11b Stem stunted, ± swollen and curved. S. nutans, otites, viscaria: Caryocolum amaurella

12a Up to 30 (40) mm long and 8 (10) mm thick spindle-shaped-cylindrical gall, situated in the shortened internodes. A long tunnel in pith containing a dirty-grey, brown-headed caterpillar => 13

12b Swellings in axial parts of shoot tips. S. hayekiana, saxifraga: Caryocolum saginella

13a On S. dichotoma, gallica, italica, nutans,otitis, parviflora: Caryocolum cauligenella

13b On S. vulgaris: Caryocolum inflativorella

14a Galls on tips or buds of main- or side shoots => 25

14b Malformations mainly on leaves, sometimes encroaching into stem parts => 15

15a Malformations only minor, bearing sori of fungi => 22

15b Malformations caused by animals => 16

16a The causers are external on the galled tissue => 17

16b Spongy, swollen on both sides, ± wrinkled or undulate swelling on petiole or leaf blade; on narrow leaves also proliferating beyond the margin. Sometimes all parts of a rosette or of young plants are disfigured. Containing many eelworms. Silene spp.: Ditylenchus dipsaci

17a Leaves folded upwards over the midrib, ± discoloured. Malformations often on many plant parts. Caused by aphids => 18

17b Shoot axis locally stunted and ± curved. Leaves deflected over their tip, undulately curled; often clustered, nest-like, on the ± stunted stem parts. S. armeria, flos-cuculi, gallica, vulgaris: Philaenus spumarius

= As causer of similar malformations of shoot and leaves Taeniothrips atratus has been sporadically indicated.

18a Aphids pale green or yellowish => 21

18a Aphids red to dark-brown or black => 19

19a Aphids black => 20

19b Aphids red to dark brown. Leaves rolled downwards. S. alba, flos-cuculi: Myzus certus

20a Young leaf blades curled or rolled slightly downwards, caused by glossy black aphid with very short, rounded cauda. Silene spp.: Brachycaudus lychnidis

20b Flat, not discoloured bulges. S. alba, dioica. Wingless aphids with dull black body and tongue-shaped cauda: Aphis fabae

21a Apterae are whitish yellow to pale green, strongly wax-powdered; body length 1.4‒2.2 mm. Antennae half the body length. Siphunculi much shorter than the oblong, black cauda. S. vulgaris and varieties: cf. Brachycolus cucubali

21b Aphid yellowish or pale green, glossy, body length 1.4‒1.8 mm. Antennae about two-thirds of body length. Siphunculi weakly clavate, pale yellowish, only slightly longer than the yellow cauda. S. alpina, atropurpurea, flos-cuculi, nutans, otites, pendula, suecica, viscaria: Volutaphis centaureae

22a Malformations bearing yellowish to yellowish-white sori => 23

22b Minor rotund or oblong dense sori, sometimes bulging on venation, bearing dark-brown, 2-celled teliospores. Silene spp.: Puccinia arenariae

23a Aecia on several Silene species, S. nutans excepted => 24

23b Aecia mainly on S. nutans. Peridium short cylindrical, with white, deflected margin, subdivided into long narrow lobes. Uromyces inaequialtus

24a Malformations and aecia similar to those of preceding fungus. Spots on upperside often reddened. Aecia disc-shaped with strongly lacerate, deflected margin. Fungus lacking uredinia, with repeated development of aecia. S. cucubalis, alpina, densiflora, dichotoma, dioica, elisabethae, maritima, noctiflora, nutans, otites, rupestris, uniflora incl. subsp. thorei, vulgaris incl. subsp. prostrata: Uromyces behenis

= Witches’ broom-like malformations after infestation on S. uniflora may also be caused by this rust fungus.

= On S. otites the aecia of a host-alternating fungus (Aecidium otitis) have been recorded repeatedly with unknown life-cycle

24b Occasionally on cultivated plants of S. coeli-rosa, etiolated shoots with narrowed, paler leaves have been observed bearing on the undersides expanded, scattered yellow sori of Melampsorella caryophyllacearum

24c Aecia arranged in circular groups on hypertrophied sori on various organs, often crowded, more rarely extending over complete leaf; accompanied by spermogonia and often uredinia, less by 2-celled teliospores. Peridium very small, short cylindrical, with lacerate white margin. S. vulgaris, more rarely S. armeria, nutans, pendula, etc.: Puccinia behenis

25a Galls not excessively pubescent => 27

25b Malformations with abnormal whitish pubescence => 26

26a Leaves on shoot densely clustered. Leaf blades rolled and ± curved, almost linear; strongly white pubescent. In case of severe infestation the whole plant is atrophied. S. nutans: Unidentified gall mite

26b Almost bud-like accumulation of severely stunted, disfigured and abnormally haired leaves on shoot tips or in axillary buds. Containing several white larvae. S. alba, densiflora, dichotoma, dioica, latifolia,noctiflora, nutans, otites: Neomikiella lychnidis

26c Similar malformations of shoot tip, lateral buds, inserted unfolding leaves with loose, fleshy thickened marginal upward roll, exceptionally also downwards. Containing several white larvae. S. nutans: Unidentified gall midge

27a Malformations ± bud-like; caused by midge larvae => 29

27b Galls elongated, not of compact bud-like appearance, caused by midge larvae as well as other inducers => 28

28a Apical parts of plant distorted and discoloured. Silene alpina: Volutaphis alpinae

28b Leaves accumulated at the shoot tip over its length loosely upwardly rolled and ± thickened, bearing aphids or thrips. S. vulgaris, nutans: cf. Brachycolus cucubali

28c Several leaves of stunted shoots distorted, variously rolled and curved. S. latifolia, vulgaris: Taeniothrips atratus

28d The upper leaf pair of shoot tip erect, slightly thickened at base; the margins folded together or rolled. Containing several white to pale orange larvae. S. vulgaris: Macrolabis sp.

28e Similar galls containing white, jumping larvae. S. vulgaris: Contarinia cucubali

28f Leaves of shoot tip bushy clustered. S. nutans, vulgaris: Unidentified gall midge

29a Up to 10 mm long, ± onion-like, glabrous galls on the axillary buds or tips of lateral shoots. Containing several white larvae. S. vulgaris: Macrolabis sp.

29b Leaves bud-like accumulated on vegetative shoots, stunted, at base broadened, thickened and ± discoloured. Larvae pink-red. S. acaulis: Jaapiella alpina

29c The youngest one- or two pairs of leaves at the tip offside shoots are narrowly rolled into one another, swollen at base and discoloured. Containing several red larvae. S. viscaria: Jaapiella viscariae

29d Several rolled glabrous leaves form a spindle-shaped bud gall at the vegetative tip, contain many cream-coloured gall midge larvae. S. behen: Macrolabis behen

30a Malformation of flowers and of flower parts caused by fungi => 40

30b Malformations of inflorescences or single flowers caused by animals => 31

30c Fruits swollen. S. alba, dioica, fruticosa: Sibinia pellucens

31a Flowers unopened, swollen. Containing midge larvae => 34

31b Flowers ± stunted, their parts variously greened or leafy => 32

32a Malformations associated with a strong stunting of inflorescence => 33

32b Malformations usually restricted only to the sometimes shortened axial parts of stem. All flower parts leafy inside the hardly changed calyx. Inflorescence axis sometimes ± developing further. S. nutans, otites, rupestris: Aceria silenes

32c Malformations on S. “parviflora”: Eriophyes parviflorae

32d Flowers greened, transformed into small shoots bearing strongly pubescent little leaves. Also the vegetative buds may develop similarly disfigured, ± elongated, dense bunches. S. alba, dioica, latifolia vulgaris: Unidentified ? gall mite

32e Inflorescence stunted, disfigured, flowers clustered. Conspicuous pubescence absent, calyx widened, enclosing greened organs. Unidentified gall mite

33a Complete host stunted, flowers greened. S. dichotoma: Inducer unknown, ? virus

33b Flowers on usually severely stunted plants transformed into a widely protruding rosette of variously disfigured little leaves; stamens hardly disfigured but greened. S. alba: Inducer unknown – ? virus

33c Axial parts of inflorescence ± compact. Flowers ± clustered; calyx swollen. Organs inside variously disfigured and greened. S. vulgaris: cf. Brachycolus cucubali

33d Similar malformations on inflorescence. S. alba, vulgaris, occasionally S. baccifera, borysthenica, coronaria, dioica, italica, latifolia, uniflora, viscaria: Brachycaudus lychnidis

33e On S. dioica. Between strongly inflated calyx and stunted corolla: cf. Brachycaudus lychnidis or B. klugkisti

34a Galls usually with dense abnormal pubescence => 39

34b Galls not, or only slightly more pubescent than the normal organs => 35

35a On Silene species, but not S. alba, dioica, latifolia => 36

35b On S. alba, dioica, latifolia. Flower buds swollen, stunted, mostly unopened, on usually inconspicuously shortened axial parts of inflorescence. Containing several midge larvae, at first white, soon yellow, jumping: Contarinia steini

36a On Silene species, S. italica, vulgaris excepted => 37

36b On S. italica, vulgaris & subsp. glareosa: Calyx conspicuously swollen, largely unopened. Also the other flower parts enlarged and exceptionally ± leafy. Larvae yellowish to pale red: Jaapiella floriperda

36c Also described for similar galls on same hosts. Larvae white: Jaapiella cucubali or J. inflatae

37a On Silene species, but not S. atropurpurea, flos-cuculi, viscaria => 38

37b On S. flos-cuculi, viscaria, similar galls contain many red larvae: Dasineura praticola

37c On S. viscaria, similar galls contain only 4–8 red-yellow larvae: Jaapiella moraviae

38a On Silene species, but not S. nutans => 00

38b On S. nutans. Flowers stunted; ± globular, unopened, hardly swollen. Sometimes on the ± shortened axial parts clustered into rotund, sometimes weak whitish pubescent balls. Containing midge larvae. Unidentified gall midge

38c On S. nutans. Swollen flower buds, abnormally pubescent. Calyx strongly thickened. Larvae yellowish to pale red: Dasineura bergrothiana

39a On S. bupleuroides. Flower buds swollen, pale, unopened. Calyx thickened; corolla greened. Containing several yellow larvae. Unidentified gall midge

39b On S. otites. Flowers transformed into a rotund gall, up to 4 mm. Calyx abnormally pubescent. Corolla greened. Stamens ± normal. Containing red, non-jumping larvae. Dasineura sp.

39c Similar galls on S. parviflora, pseudotites: Unidentified gall midge

= In C-Eu occasionally galls on S. nutans, otites consisting of several, densely clustered, severely stunted and whitish pubescent buds; between the buds live white larvae of a gall midge assigned to Neomikiella lychnidis. Galls on these hosts often simultaneously occurring in vegetative shoot tips or lateral buds

40a Fungus fructifies in the ± distinctly swollen anthers. Spores separated, not arranged in easily decomposing balls; ± violet tinged. Other flower parts not galled => 43

40b Flower buds stunted, unopened, transformed into globular to broad egg-shaped galls. Inner part soon destroyed and displaced by a yellow- to tobacco-brown spore mass, consisting of many easily decomposing balls => 41

40c lowers leafy or partially greened. Organs variously disfigured, transformed into sometimes ± clustered, ± reddish tufts. S. viscaria: Cause unknown

41a On several Silene species, S. otites excepted => 42

41b On. Silene otites. Diseased flowers distorted; often distinctly swollen, for a long period unopened, corolla usually atrophied. Sori rupturing later on and with dusting: Microbotryum majus

42a On Silene alba, alpestris, dioica, nutans, rupestris, vulgaris. Flowers outwardly hardly changed. Infestation caused by this fungus results in an early opening of the flower accompanied by a shortening and swelling of the stamens, and in the female flowers a transformation into similarly disfigured anthers: Microbotryum violaceum

= Microbotryum heliospermae is an anther smut fungus occurring on alpine S. pusilla; M. silenes-saxifragae is an anther smut fungus on S. saxifraga

42b On many other Silene species. Flowers outwardly hardly changed. Spore mass usually pale grey-violet: Microbotryum silenes-inflatae

= The smut fungus Microbotryum silenes-dioicae transforms the content of the anthers of S. dioica into a brown vinaceous mass of spore

= Note: because the fungus leaves the ovary intact, the negative impact on the reproductive capacity of the flower is very limited. The real damage is caused by the gall midge Contarinia steini, see lead 35b.

= Microbotryum silenes-acaulis has been reported on S. acaulis, uniflora

43a On S. alba, dioica, latifolia, mollissima, nutans, repens, thymifolia, uniflora, velutina, vulgaris: Thecaphora melandrii

43b On S. flos-cuculi, viscaria: Thecaphora saponariae

mod 7.xii.2019