Description from Flora of China
Herbaceous or woody climbers, rarely shrubs. Leaves usually biternate or bitrilobate; stipules small, deciduous; leaflets pinnately lobed or dentate, usually with pellucid glands. Panicles axillary; peduncles rather long, first pair of branches forming tendrils or spines; bracts and bracteoles subulate. Flowers unisexual, zygomorphic, with slender noded pedicels. Sepals 4 or 5, imbricate, outer 2 smaller. Petals 4, with a large scale inside and slightly above base; scales of abaxial petals with broadly winged appendage, scales of adaxial petals simple. Disk lobed into 2 large glandular lobes at base of petals. Stamens (male flowers) 8, slightly longer than petals. Ovary (female flowers) ellipsoid, trigonous, 3-loculed; ovules 1 per locule, inserted at middle of middle axis; style short; stigma 3-lobed. Capsules inflated, saclike, 3-loculed; pericarp membranous or papery, veined. Seeds 1 per locule, subglobose; hilum cordate or suborbicular; embryo with large cotyledons, outer one arched, inner one reflexed. 2n = 20, 22.
About 12 species: mostly in tropical and subtropical America; one species in China.