gallers on genus Rhinanthus

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