Description from Flora of China
Annual or perennial herbs, subshrubs, or shrubs, often sometimes spiny, glabrous or hairy; hairs basifixed or symmetrically or asymmetrically bifurcate, white or black, at margins of stipules and bracts often with minute subsessile glands. Leaves paripinnate or imparipinnate or leaflets rarely verticillate; stipules green or membranous, adnate to petiole or free, often vaginate-connate behind stem. Racemes axillary, sessile or pedunculate, loosely or densely few to many flowered. Flowers subsessile or with a distinct pedicel; bracteoles sometimes present. Calyx campanulate to tubular, with 5 equal or unequal teeth mostly hairy on inner side, sometimes inflated in fruit. Petals glabrous or more rarely hairy; standard mostly emarginate at apex, more rarely rounded, mostly with a ± distinct claw; wings auriculate at limb base. Stamens diadelphous, rarely monadelphous, with uniform anthers. Ovary sessile or stipitate; style below or at capitate stigma rarely hairy or penicillate. Legumes very variable, mostly keeled ventrally and grooved dorsally, 1-locular, incompletely or completely 2-locular; walls membranous, leathery or rarely hard and legumes then nutlike. Seeds rectangular-reniform, estrophiolate.
Several species and varieties of the genus described from China, the types of which are housed in several small herbaria, have not been seen by us. The taxonomic value of these taxa is therefore uncertain. They are treated here according to the original diagnosis only.
The measurements of legumes do not include the stipe and beak.
About 3,000 species: ca. 2,500 species in the Old World, represented in nearly all parts of the N Hemisphere, ca. 500 species in the New World; 401 species (221 endemic) in 59 sections (two endemic) in China.
(Authors: Xu Langran (徐朗然 Xu Lang-rang); Dietrich Podlech)