Description from Flora of China
Climbers, with simple hairs, usually pubescent to tomentose and sometimes copiously so. Leaf blade with many stout parallel secondary veins. Inflorescences mostly leaf-opposed or terminal, less often axillary or infra-axillary, 1- to many flowered and forming cymes, glomerules, or branched panicles. Pedicel often with several bracteoles from base to middle. Flower buds ovoid or oblong-conic. Sepals 3, small, valvate, connate at very base. Petals 6, in 2 whorls, valvate, leathery, margin thickened; outer petals slightly larger than inner petals, erect or spreading, inside flat to convex; inner petals 3-edged, base concave. Stamens many; connectives slightly enlarged, apically oblique, obtuse, or slightly apiculate. Carpels many, free, often pubescent, slightly curved, grooved on inner side; ovules 1-16 per carpel, in 1 or 2 sutural series; styles sometimes narrowly clavate but usually not enlarging; stigmas very short and not clearly differentiated from style, apex 2-cleft or entire. Fruit apocarpous; monocarps few to many, stipitate, spherical, ovoid, or oblong, thick walled, usually pubescent to tomentose. Seeds 1-10 per monocarp, in 1 or 2 series, smooth, shiny.
About 75 species: Old World tropics and subtropics; 23 species (eight endemic) in China.
(Authors: Li Bingtao (李秉滔 Li Ping-tao); Michael G. Gilbert)