Description from Flora of China
Crotalaria roxburghiana Candolle.
Herbs, annual or short-lived perennial, erect, 30-80 cm tall. Branches terete, densely coarsely pilose. Stipules filiform, ca. 1 mm, persistent or caducous. Leaves simple, subsessile; leaf blade oblong-linear to linear-lanceolate, 3-12 × 0.5-1.5 cm, abaxially densely brownish pilose, adaxially pilose on midvein, base narrow, apex acute. Racemes terminal, usually condensed or headlike, 3-12-flowered, often with solitary axillary flowers below; bracts lanceolate, slightly ovate-falcate, 1-2 cm. Pedicel 2-4 mm, thick; bracteoles inserted at base of calyx tube or on middle or apical part of pedicel, similar to bracts but shorter. Calyx 2-lipped, 2-3 cm, parted to base, abaxially brownish pilose; lobes lanceolate. Corolla yellow, included in calyx; standard obovate to suborbicular, 1.5-2.5 cm, base with 2 appendages, apically pubescent; wings narrowly elliptic, ± as long as standard; keel with a long straight shortly twisted beak. Legume black when mature, subcylindric, 2-2.5 cm, 20-30-seeded, glabrous. Fl. Jun-Sep, fr. Oct-Dec.
Open forests, along trails; below 100-2400 m. Fujian, Guangdong, Guangxi, Hainan, Sichuan, Taiwan, Xizang, Yunnan [Bangladesh, Bhutan, Cambodia, India, Indonesia, Laos, Malaysia, Nepal, Pakistan, Philippines, Sri Lanka, Thailand, Vietnam; Africa, Australia, Pacific islands].