Dichotomous table for gallers on Ononis
by Hans Roskam
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