Description from Flora of China
Calpidia Thouars; Ceodes J. R. Forster & G. Forster.
Shrubs, trees, or vines. Stems sometimes armed. Leaves opposite or alternate, petiolate, margin entire. Inflorescences axillary (or terminal), many-flowered cymes or panicles; bracts absent or inconspicuous, caducous. Flowers unisexual (plant dioecious), bisexual, or polygamous; bracteoles 2-4. Male perianth limb campanulate or funnelform. Stamens 6-10. Female perianth ovate-tubular or cylindric, 5-10-lobed. Ovary sessile, oblique. Stigma capitate or lobed. Fruit oblong or clavate, ribbed, with sticky glands. Seed oblong, with a deep longitudinal furrow; embryo straight, cotyledons recurved, enclosing the endosperm.
Some authors place freestanding plants that have bisexual or polygamous flowers and fruits with sessile glands in the genus Ceodes and recognize up to 75 species, but most modern authors believe the similarities between the groups outweigh the differences and recognize only one genus with 35(–40) species. The very sticky fruits can attach to birds, and species of Pisonia are often common on isolated islands hosting colonies of sea birds.
Between 35 and 40(–75) species: tropical and subtropical regions, most diverse in SE Asia and tropical America; three species in China.