Shrubs, small trees, or vines, evergreen, erect, climbing, or sometimes prostrate. New branches often with branched or simple trichomes, glabrescent or sometimes with persistent trichomes; branchlet base sometimes with subulate scales (cataphylls). Stipular spines straight or curved, sometimes absent. Leaves alternate, spirally arranged or distichous [or secund], simple, petiolate or sometimes subsessile; leaf blade herbaceous to leathery, margin entire. Inflorescences superaxillary, axillary, or terminal, racemes, corymbs, umbels, or panicles, sometimes reduced to a single flower but usually 2-10-flowered; bract usually present at base of pedicels but often caducous. Sepals 4, in 2 whorls; sepals of outer whorl often thick, often inwardly concave or becoming navicular, covering other flower parts, sometimes basal one becoming saccate; sepals of inner whorl often thin, ± equal. Petals 4, imbricate, often 2 pairs roughly similar; anterior pair of petals distinct, clawless or sometimes clawed; posterior pair of petals with lateral margins adhering, base asymmetric, margin revolute or rarely inner lateral margin involute from base to near middle, base fully covering disk; petals sometimes all 4 ± equal, distinct. Stamens 7-120. Gynophore ± as long as filaments, scarcely lengthening in fruit but often becoming thicker, sclerified; ovary 1-loculed; placentae 2-6(-8); ovules few to many; style short or obsolete; stigma sessile. Fruit baccate, globose or ellipsoid, often with different color when mature or dry, usually not dehiscent. Seeds 1 to numerous per fruit, reniform to nearly polygonal; embryo bent.

Between 250 and 400 species: mostly in tropical and subtropical regions worldwide but some in temperate regions; 37 species (ten endemic) in China.