Description from Flora of China
Trees, rarely shrubs, monoecious or dioecious. Leaves paripinnate, alternate, petiolate; leaflets entire. Thyrses terminal or axillary. Flowers unisexual, actinomorphic, small; bracts and bracteoles small. Calyx cupular, 5- or 6-lobed; sepals small, valvate or imbricate, often opening early. Petals absent or 5 or 6. Disk annular, entire or lobed. Stamens (male flowers) 6-8, exserted; filaments villous. Ovary (female flowers) obcordiform, 2(or 3)-lobed, 2(or 3)-loculed, densely tuberculous; ovules 1 per locule; style inserted between ovary lobes; stigma 2- or 3-lobed. Fruit deeply parted into 2 or 3 schizocarps, usually 1 developed, ellipsoid; pericarp leathery, with soft spines. Seeds same as schizocarps in shape; arillode fleshy, adnate to testa, thoroughly covering seeds; embryo arched or slightly straight, cotyledons thick. 2n = 22.
See the revision by Leenhouts (Blumea 31: 373-436. 1986).
About 22 species: SE Asia; three species (one endemic, one introduced) in China.