Description from Flora of China
Indigofera hosiei Craib; I. longispica Gagnepain; I. micrantha Bunge (1833), not Desvaux (1826); I. pseudotinctoria Matsumura.
Shrubs, erect, 40-100 cm tall. Stems brown, terete; branches whitish gray, with appressed white medifixed symmetrically 2-branched trichomes. Stipules triangular, ca. 1 mm, caducous. Leaves 2.5-5 cm, 5-9(or 11)-foliolate; petiole and rachis with appressed medifixed trichomes; petiole 0.4-1.6(-2) cm; stipels very small; petiolules ca. 0.5 mm; leaflet blades opposite, elliptic, 5-15(-25) × 3-10(-15) mm, abaxially pale green and with longer medifixed trichomes, adaxially green and with sparse appressed medifixed trichomes or glabrescent, base rounded, apex obtuse. Racemes 4-6(-10) cm; peduncle 1-5 mm; bracts linear, ca. 1.5 mm. Pedicel 1-2 mm. Calyx 2-2.5 mm, with appressed white medifixed trichomes; teeth triangular-lanceolate, equal, ca. 2 × as long as tube. Corolla purple to purplish red; standard broadly obovate, 5-6 mm, outside with appressed medifixed trichomes; wings and keel equal, ca. 5.5 mm; keel with spur in middle. Stamens 4-5 mm; anthers globose, apex mucronate. Ovary linear, sparsely hairy. Legume cylindric, straight, 2-2.5 cm, with appressed white medifixed trichomes; endocarp red blotched. Seeds ellipsoid, ca. 2 mm. Fl. May-Jul, fr. Aug-Oct. 2n = 16.
Grasslands, river beaches, slopes; 500-2300 m. Anhui, Chongqing, Fujian, Gansu, NE Guangxi, Guizhou, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Liaoning, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shandong, Shanxi, Sichuan, E Xizang, Yunnan, Zhejiang [Japan, Korea].