Dichotomous table for gallers on Nasturtium
(see also Rorippa)
by Hans Roskam
1a Galls on parts above ground => 2
1b Roots conspicuously curved and swollen. N. officinale: Spongospora nasturtii
= The snout beetle Ceutorhynchus assimilis, inducing root collar galls on many crucifers, also occurs on N. officinale, but occasionally without causing galls
= The cyst developing eelworm Heterodera cruciferae has been recorded on Nasturtium
2a Malformations on vegetative organs => 3
2b Flowers swollen, unopened. Corolla stunted, like other parts disfigured and ± thickened. Larvae whitish to lemon-yellow. N. microphyllum, officinale: Contarinia nasturtii
3a Malformations caused by fungi, with fruiting bodies on their surface => 4
3b Axis of young shoots stunted, inserted parts clustered. leaves or leaflets deflected, curled and discoloured deep green close to the froth-covered nymph. N. microphyllum, officinale: Philaenus spumarius
4a Fungus sori dense, at first closed, glossy, porcelain-like, conidia developing in rows, later on with mealy dusting. N. microphyllum, officinale: Albugo candida
4b Fungus fruiting on branched conidiophores, developing in loose down of branched conidiophores. N. officinale: Hyaloperonospora nasturtii-aquatici