Description from Flora of China
Subshrubs, shrubs, or perennial herbs. Leaves pinnately compound, 3-foliolate; stipule small, subulate or linear, persistent or caducous; stipels absent; leaflets entire. Racemes axillary or flowers fasciculate; bracts persistent, 2-flowered at each bract; bracteoles 2, often persistent; flowers often dimorphic, corollate or not (cleistogamous plants). Calyx campanulate; tube short; lobes 5, upper 2 often connate at base. Corolla exserted; standard oblong or obovate; wings oblong, straight, clawed, auriculate, connivent with keel; keel obtuse and incurved. Stamens 10, diadelphous (9+1), equal. Ovary superior, 1-ovuled; style incurved; stigma terminal. Legume ovoid, obovoid, or ellipsoidal, rarely slightly globose, lenticular, indehiscent, reticulate veined, 1-seeded.
Because most species can tolerate arid soils, they are good for soil conservation and sand stabilization. They are also used as honey plants and for nitrogen fixation. The young shoots and leaves are used as forage for livestock and as green manure.
About 60 species: E Asia to India and North America, introduced from Malesia to NE Australia; 25 species (ten endemic) in China.
(Authors: Huang Puhua (黄普华 Huang Pu-hwa); Hiroyoshi Ohashi, Tomoyuki Nemoto)