Description from Flora of China
Herbs, perennial. Stems erect or diffuse, branched. Leaves 1-foliolate, rarely pinnately 3-foliolate, stipulate and stipellate; stipules scarious or nearly leathery, free or connate. Racemes axillary or terminal; flowers small, mostly ca. 5 mm, usually binate at each node of rachis; bracts scarious, early deciduous. Calyx 4-lobed; lobes dry, rigid, nearly equal, upper lobe 2-toothed at apex. Corolla not or slightly longer than calyx; standard broad, obovate or nearly orbicular; keel obtuse, adherent to wings. Stamens diadelphous (9+1); anthers uniform. Ovary sessile or nearly so, many ovuled; style linear, incurved; stigma capitate. Legume cylindric, swollen, many jointed, 1-seeded per article, indehiscent.
About 30 species: tropical Africa, Asia, Australia, and tropical America; five species (one endemic, one introduced) in China.
(Authors: Huang Puhua (黄普华 Huang Pu-hwa); Hiroyoshi Ohashi)