1a Malformations of parts above ground => 4

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

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

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

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

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

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

4a On flowers or fruits => 21

4b On vegetative plant parts => 5

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

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

6a On shoot tips => 7

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

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

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

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

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

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

9b On stems or leaves => 10

10a On leaf midrib or leaf blade => 12

10b On stems => 11

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

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

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

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

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

12a Galls larger than 1 mm => 13

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

13a Galls with leaf blade parts involved => 15

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

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

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

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

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

16a Gall wall fleshly thickened => 18

16b Gall wall only slightly thickened => 17

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

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

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

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

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

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

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

19a Galls mainly on M. lupulina => 20

19b Buds swollen, onion-like; gall usually on lateral buds, soft, rotund or oblong, glabrous, ± yellowish, also reddish. Stipules strongly enlarged. Opening at top at maturity, containing several orange-red larvae. M. falcata, littoralis, minima, prostrata, sativa, truncatula, x varia: Dasineura medicaginis

20a Similar, tough-walled galls ± pubescent, often situated terminally, opening by a slit at maturity. Larva maize-yellow. M. falcata, lupulina, minima, orbicularis, polymorpha, sativa subsp. varia: Dasineura lupulinae

20b Up to 5 mm long and 4 mm broad, rotund or ± egg-shaped, closed galls, often overtopped by an atrophied stalked mid leaflet. Sometimes ± enveloped by the swollen stipules. Inner wall with mycelium. Containing a single larva. M. lupulina, minima: Asphondylia lupulinae

21a On fruits => 24

21b On flowers => 22

22a On single flowers => 23

22b Usually all flowers of a raceme are variously greened or leafy, depending on their response ability. M. carstiensis, falcata, littoralis, lupulina, minima, sativa: Aceria plicator

23a Flower buds more or less swollen, onion-like, up to 8 mm long; calyx yellowish. Corolla unopened, its parts ± coalesced, terminal part often beak-shaped. Larvae at first white, later on lemon yellow; gregarious; jumping. M. arabica, falcata, sativa incl. subsp. varia: Contarinia medicaginis

23b Buds soon stunted, ± curved. Occasionally slightly swollen; containing a compact, narrow- and brown-headed, dark cream yellow, strongly bent beetle larva. M. arborea, falcata, lupulina, sativa, x varia: Holotrichapion pisi

24a Pod distinctly shortened, swollen (especially the mid part), often slightly curved at the top. Wall succulent, inside with fungus. M. falcata, sativa, saxatilis: Asphondylia miki

24b Pod conspicuously shortened, transformed into an egg-shaped pouch, often partially enveloped by withered corolla; wall slightly succulent, thickened, inside without fungus. Containing a dirty cream coloured beetle larva with a small brown head. M. falcata, sativa incl. subsp. varia: Tychius medicaginis