Description from Flora of China
Indigofera potaninii Craib.
Shrubs, 0.8-2.5 m tall. Stems rufous to blackish brown, terete, with sparse scattered yellow lenticels; young branches angular, with dense appressed mixed white and brown medifixed symmetrically 2-branched trichomes, glabrescent. Stipules lanceolate, 2.5-4 mm, stiff. Leaves 4-10 cm, (5 or)7-13-foliolate; petiole and rachis adaxially flat, with appressed white medifixed trichomes; petiole 0.5-1.5(-2.5) cm; stipels ca. 0.5 mm; petiolules ca. 1 mm; leaflet blades opposite, elliptic, obovate, oblong, or obovate-oblong, 5-20(-30) × 4-9(-10) mm, papery, both surfaces with dense appressed white medifixed trichomes, abaxially pale green, adaxially green, midvein adaxially flat or slightly depressed, secondary veins not visible on both surfaces, base rounded to cuneate, apex rounded, truncate, or acute and mucronate. Racemes 10-19 cm; peduncle 0.8-5 cm, hairy; bracts ovate to linear-lanceolate, 1.5-3 mm, caducous, with appressed medifixed trichomes. Pedicel 1.5-2 mm, hairy. Calyx 2-3.5 mm, with appressed brown medifixed trichomes; tube 1-1.5 mm; teeth triangular, 1-2 mm. Corolla crimson-red; standard broadly ovate-elliptic to obovate-elliptic, 7.5-9.5 × 5-6.5 mm, outside with appressed medifixed trichomes; wings 7.5-9.5 × ca. 2.5 mm, base clawed, margin ciliate; keel 7.5-9.5 mm, outside apically hairy, margin ciliate. Stamens 7.5-8.5 mm; anthers ovoid-globose, glabrous. Ovary hairy, with 8-10 ovules. Legume linear, cylindric, spreading or drooping, 3.5-4 cm, with sparse appressed medifixed trichomes when young, glabrescent. Seeds 8 or 9 per legume, 2.5-3 × ca. 2 mm. Fl. May-Jun, fr. Jul-Oct.
Indigofera potaninii differs from I. szechuensis only by the size of the leaves and inflorescences, which change very substantially as the plant grows from early spring through late summer. Most material cultivated in England as I. potaninii is not this species but I. howellii (see comment under that species, p. 159). The epithet is sometimes given as "szechuanensis," but this is not correct.
● Slopes, trailsides, riverbanks; 2500-3800 m. W Gansu, Sichuan, E Xizang, NW Yunnan.