Dichotomous table for gallers on Colchicum
by Hans Roskam
1a Linear, 1–3 mm broad, up to 10 (20) mm long, spindle-shaped tapering bulges of the veins predominantly the terminal, but also other above-ground and subterranean leaf parts; at first closed, lead-grey translucent; later on irregularly splitting open, with black-brown dusting of spore balls. Often many per leaf, sometimes coalescing. Colchicum spp.: Urocystis colchici
1b Above-ground parts with local, pale-green, spongy swellings; containing many eelworms inside. C. autumnale: Ditylenchus dipsaci