Description from Flora of China
Enchidium Jack; Poilaniella Gagnepain; Prosartema Gagnepain.
Trees or shrubs, monoecious. Leaves simple, alternate, rarely opposite to nearly whorled; stipules small, persistent or deciduous; leaf blade unlobed, pinnately veined, sometimes stipulate at base, paired glands at apex of petiole. Flowers androgynous or anisogynous; inflorescences terminal or axillary, racemose or thyrsoid. Male flowers: sepals 5, free, imbricate; petals 5, exceeding calyx; disk cupular or annular, or shortly divided, or dissected, sometimes divided into 5 glands; stamens 3-5; filaments connate or only free at upper part; anther connective enlarged, often elongated, thecae adnate to thickened connectives; pistillode absent. Female flowers: pedicels usually prominently stronger than axil of inflorescence; sepals and petals as in male; disk annular or cupular, usually unlobed; ovary 3-locular; ovules 1 per locule; styles 3, free, connate at near base, bifid or unlobed at apex. Capsules 3-valved. Seeds not carunculate; testa dry; endosperm present; endosperm fleshy; cotyledon broad and flat.
See P. T. Li et al. (Harvard Pap. Bot. 11: 117-120. 2006) for a review of Trigonostemon in China.
About 50(-80) species: tropical Asia, extending from India and Sri Lanka to New Guinea; eight species (one endemic) in China.
(Authors: Li Bingtao (李秉滔 Li Ping-tao); Michael G. Gilbert)