Description from Flora of China
Goniogyna Candolle; Heylandia Candolle; Priotropis Wight & Arnott.
Herbs or shrubs, often short-lived, rarely small trees. Stems terete or angled. Stipules filiform to leaflike or lacking. Leaves simple or 3-foliolate, usually petiolate. Inflorescences terminal, leaf-opposed, or occasionally axillary, racemose, occasionally condensed and headlike; bracts usually present. Flowers usually pedicellate; bracteoles 2, rarely lacking. Calyx subcampanulate, with 5 subequal lobes or 2-lipped with 3 narrow abaxial lobes and 2 broader adaxial lobes often connate or partly connate. Corolla usually yellow, less often white, purplish red, or dark purplish blue; standard usually orbicular or oblong, outside glabrous or with trichomes, basally almost always with 2 appendages inside; wings oblong or narrowly elliptic; keel rounded to angled, generally extended into a well-developed beak. Stamens monadelphous, dimorphic, 5 usually shorter with oblong and basifixed anthers alternating with 5 longer with ovoid and dorsifixed anthers. Ovary stipitate or sessile, with or without trichomes, with 2 to many ovules; style long, basally curved or geniculate, almost always with 1 or 2 lines of trichomes on apical part; stigma minute, oblique, rarely 2-lobed. Legume subsessile to long stipitate, oblong, cylindric, ovoid-globose, or rarely rhombic, usually conspicuously inflated, rarely compressed, 2- to many seeded, with or without a stipe. Seeds obliquely cordate to oblong-reniform, with a definite hilar sinus.
The indumentum of many species of Crotalaria darkens significantly in herbarium collections and is often variously described as yellow or brown, but in living material it may often be ± colorless rather than as indicated in many descriptions.
Some species of Crotalaria are grown as fiber crops, fodder, and green manure, while others are used medicinally and as ornamentals. Pyrrolizidine alkaloids are present in some species, which in livestock can cause acute or more often chronic poisoning known as "crotalism."
About 700 species: throughout tropics and extending into subtropics, most numerous in E and S tropical Africa; 42 species (nine endemic, six introduced) in China.
(Authors: Li Jianqiang (李建强), Sun Hang (孙航); Roger M. Polhill, Michael G. Gilbert)