Description from Flora of China
Shrubs or small trees. Young branches and leaves with peltate scales. Leaves alternate; stipules small, sheathing bud, fugacious; petiole swollen at base and apex; leaf blade simple, palmately veined. Inflorescence a terminal panicle. Flowers bisexual, actinomorphic. Sepals 5, free, imbricate, with basal, abaxial glands, fugacious. Petals 5, imbricate, large and conspicuous. Stamens many, free or slightly united at base; anthers oblong, with 2 inverted, U-shaped thecae, dehiscing by short, apical slits on bend. Ovary superior, 1-loculed; ovules many on 2 parietal placentas; style slender; stigmas 2-lobed. Fruit a capsule, loculicidally 2-valved, usually spiny. Seeds many; testa red, slightly fleshy; embryo large; cotyledons broad, incurved at apex; endosperm copious.
Molecular data suggest that the genus Diegodendron Capuron, endemic to Madagascar, is related to Bixa and could be included within the Bixaceae.
Zhang Pengyun & Zhang Yaojia. 1990. Bixaceae. In: Li Hsiwen, ed., Fl. Reipubl. Popularis Sin. 50(2): 180.
One genus and five species: native to tropical America; one species widely cultivated in tropical regions, including China.
(Authors: Yang Qiner (杨亲二); Michael G. Gilbert)