Description from Flora of China
Shrubs, shrublets, perennial herbs, or rarely annual herbs or small trees; trichomes typically medifixed (T-shaped), equally to very unequally 2-branched and sometimes crisped, or rarely simple multicellular hairs present with glandular tips. Stipules persistent or caducous. Leaves usually imparipinnate but for some species simple or reduced to 1 leaflet; stipels present or absent; leaflet blades usually opposite but sometimes subopposite or alternate, rarely with glands, margin entire. Racemes axillary; bracts usually caducous. Calyx campanulate or cup-shaped; teeth 5, subequal or abaxial one longer. Corolla usually reddish, sometimes white or yellow; standard usually covered outside with appressed trichomes but occasionally glabrous, base shortly clawed, apex usually obtuse to emarginate and mucronate; wings narrow, base auricled; keel falcate or spatulate, with spur adnate to wings. Stamens 10, diadelphous, only vexillary one free; anthers uniform, basifixed or subbasifixed, sometimes both ends hairy, apex apiculate; pollen 3-colporate. Ovary sessile, with 1 to many ovules; style linear, usually glabrous; stigma capitate. Legume linear, oblong, or ovoid, cylindric or 4-sided in cross section, 2-valved, septate, dehiscent; endocarp often spotted with tannin deposits. Seeds globose to rectangular; hilum small; cotyledons unequal; radicle oblique.
A single collection has been seen from Yunnan of what appears to be an additional species closely related to Indigofera laxiflora Craib (Kew Bull. 1912: 148. 1912), otherwise only known from Thailand.
About 750 species: tropics and subtropics worldwide; 79 species (45 endemic, two introduced) in China.
(Authors: Gao Xinfen (高信芬); Brian D. Schrire)