Description from Flora of China
Herbs, perennial. Stem erect or procumbent, 30-90 cm tall, glabrous or slightly pubescent. Leaves 1-foliolate; petiole 5-14 mm, glabrous; blade often ovate-oblong or oblong-lanceolate to lanceolate, to 6.5 × 1-2 cm on upper stem, cordate, nearly orbicular, or ovate, 1-3 × ca. 1 cm on lower stem, abaxially slightly pubescent, adaxially glabrous. Racemes axillary or terminal, 1.5-7 cm, 6-12-flowered, binate at each node; internodes 2-5 mm. Pedicel 3-4 mm. Calyx 5-6 mm, slightly longer than first article of legume. Corolla red, reddish purple, purplish blue, or yellow, slightly longer than calyx, ca. 5 mm; standard obovate. Ovary pubescent, 4-7-ovuled. Legume compressed, cylindric, 1.5-2.5 cm × 2-2.5 mm, pubescent, 4-7-jointed, not constricted between articles, with raised linear ridges. Seeds ellipsoidal, slightly compressed. Fl. Sep, fr. Sep-Nov. 2n = 14, 16.
It is grown for green manure and used as a forage. The whole plant is used medicinally for treating sword wounds and bone fractures.
Open grassy slopes, roadsides, sandy seashores, grasslands in parks; 100-700 m. Fujian, Guangdong, Guangxi, Hainan, Taiwan, Yunnan [Cambodia, India, Indonesia, Japan, Laos, Malaysia, Nepal, Philippines, Sri Lanka, Thailand, Vietnam; E and W Africa, throughout Old World tropics; introduced in the Neotropics].