Herbs or suffrutescent herbs, rarely small trees. Leaves abruptly pinnate; leaflets opposite; foliar glands usually present, disk- or cup-shaped, rarely flat. Flowers yellow or red. Sepals 5. Petals 5, unequal. Stamens 10 to 5 fertile, filaments straight, anther thecae ciliolate along suture, dehiscent terminally by slit or pore. Legume elastically dehiscent, valves coiling. Seeds with either smooth or pitted testa, usually exareolate.

About 270 species: mostly (ca. 240) indigenous to America, with only a few (ca. 30) in tropical Asia; three species (one introduced) in China.