31. Indigofera nigrescens Kurz ex King & Prain, J. Asiat. Soc. Bengal, Pt. 2, Nat. Hist. 67: 286. 1898.
黑叶木蓝 hei ye mu lan
Indigofera atropurpurea Buchanan-Hamilton ex Hornemann var. nigrescens E. Pottinger & Prain; I. mekongensis Jesson.
Shrubs, erect, 1-2 m tall. Stems reddish brown; young branches green, striate, with appressed brown medifixed symmetrically 2-branched trichomes. Stipules linear, 5-8 mm. Leaves 8-18 cm, 11-23-foliolate; petiole and rachis with sparse appressed medifixed trichomes; petiole 2-2.5 cm; rachis terete or slightly flattened, adaxially grooved; leaflet blades opposite, elliptic to obovate-elliptic, 1.5-2.5 × 0.7-1.3 cm, papery, both surfaces with sparse appressed medifixed trichomes, abaxially usually becoming dark or black or with black spots when dry, base broadly cuneate to rounded, apex obtuse and mucronate. Racemes ca. 19 cm, densely flowered; peduncle ca. 2 cm; bracts linear, 5-7(-9) mm, abaxially with brown medifixed trichomes. Pedicel 1-1.5 mm, with brown medifixed trichomes. Calyx 3-5 mm, with appressed brown and white medifixed trichomes; tube 2.5-3 mm; teeth triangular, most abaxial one ca. 1 mm. Corolla red to purple; standard obovate, 6.5-7 × ca. 4 mm, outside with appressed brown and white medifixed trichomes, inside basally hairy, base clawed, apex obtuse; wings 5.5-6 mm, margin ciliate; keel as long as wings, outside apically hairy, margin ciliate, spur ca. 1 mm. Stamens 4-5 mm; anthers ovoid-globose, base with a few trichomes. Ovary glabrous, with 8 or 9 ovules. Legume cylindric, 1.7-2.8 cm, with sparse appressed medifixed trichomes, apex obtuse; endocarp blotched. Seeds 7 or 8 per legume, reddish brown, ovoid, ca. 2.5 mm. Fl. Jun-Sep, fr. Sep-Oct.
Hills, scrub, sparse forests, sunny grasslands, fields, river beaches; 500-2500 m. Fujian, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Jiangxi, Shaanxi, Sichuan, Taiwan, SE Xizang, Yunnan, Zhejiang [India, Indonesia, Laos, Myanmar, Philippines, Thailand, S Vietnam].