Description from Flora of China
Shrubs or small trees, sometimes polygamo-dioecious, unarmed; branches sometimes superaxillary. Raphides absent. Leaves opposite, sometimes with domatia; stipules persistent or deciduous, shortly united around stem, triangular. Inflorescences axillary or sometimes supra-axillary, cymose to fasciculate or glomerulate, few to many flowered, sessile to pedunculate, bracteate. Flowers subsessile to pedicellate, bisexual and monomorphic or unisexual. Calyx limb truncate to 4(or 5)-lobed or -denticulate. Corolla white, pale green, or pale yellow, salverform, inside pubescent in throat and sometimes on lower part of lobes; lobes 4(or 5), convolute in bud. Stamens 4(or 5), inserted in corolla throat, exserted; filaments short; anthers dorsifixed. Ovary 2-celled, ovules 1-3(-6) in each cell on axile placentas; stigma 2-lobed, shortly exserted. Fruiting pedicels often elongating notably. Fruit yellow, orange, or red, baccate, subglobose or ellipsoidal-globose, fleshy or leathery, with calyx limb usually persistent; seeds several, medium-sized, angled, subglobose, or somewhat flattened, embedded in pulp derived from placenta; hilum linear or comma-shaped; radicle hypogynous.
This genus was reviewed by Robbrecht and Puff (Bot. Jahrb. Syst. 108: 114-119. 1986), then in more detail by Ali and Robbrecht (Blumea 35: 279-305. 1991). The description of the sexuality of the plants and flowers here follows Ali and Robbrecht (loc. cit.) and Puff et al. (Rubiaceae of Thailand, 84. 2005).
About 20 species: tropical and subtropical Asia; three species (one endemic) in China.
(Authors: Chen Tao (陈涛); Charlotte M. Taylor)