Description from Flora of China
Lianas. Cymes often racemelike, sessile or short pedunculate, often 2 at a node. Flowers small. Calyx with basal glands. Corolla campanulate; lobes ca. as long as tube, twisted to right or subvalvate, interior of tube with 5 longitudinal ridges, sometimes produced into fleshy appendages and/or with lines of hairs along each side. Corona lobes otherwise absent. Filaments connate into a tube; anthers erect, apical appendages membranous; pollinia 2 per pollinarium, oblong, erect. Stigma head hemispherical, obtusely conical or clavate and beaked, exceeding anthers. Follicles solitary or paired and widely divergent, ovoid to strongly beaked, often broad at base.
About 25 species: tropical or subtropical Asia, S Africa, and Oceania; seven species in China.