Herbs erect, perennial. Rootstock usually a subglobose tuber [sometimes a cluster of swollen roots]. Leaves opposite, sessile or subsessile. Inflorescences umbel-like or racemelike. Pedicel slender, short. Calyx with 5 basal glands. Corolla campanulate to subrotate; lobes erect or spreading, valvate. Corona double, attached to staminal column, outer series of 5 deeply 2-cleft lobes exceeding staminal column, inner series of 5 oblong lobes incumbent over stigma head, not or hardly exceeding staminal column. Filaments connate into a short tube; anthers without membranous apex; pollinia 2 per pollinarium, erect or ascending, with a translucent margin. Stigma head depressed. Follicles often linear, usually paired. Seeds comose.

About 60 species: mostly in Africa, also in Oceania and SE Asia; two species in China.