gallers on Euphrasia

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