Description from Flora of China
Herbs, perennial. Roots thickened, carrot-shaped. Stems voluble. Leaves opposite or alternate. Flowers solitary, axillary or almost opposite to leaves, or in cymes of 3, pedicellate, 4-7-merous. Calyx tube (hypanthium) adnate to ovary to different extents, or free from ovary. Corolla epigynous; tube obvious; limb 5(or 6)-lobed. Stamens 5; filaments glabrous or hairy. Ovary completely inferior, or inferior only to corolla but inferior, semi-inferior, or superior to calyx, 3-6-locular; style glabrous or hairy; stigma 3-6-fid. Berry globose, apically flat. Seeds numerous.
Two species: Bhutan, China, NE India, Indonesia, Japan, Laos, Myanmar, Nepal, Thailand, Vietnam; two species in China.
(Authors: Hong Deyuan (洪德元); Thomas G. Lammers, Laura L. Klein)