Herbs, erect, to 1.5 m tall. Branches terete, sericeous. Stip­ules linear, minute. Leaves simple; petiole 2-3 mm; leaf blade oblanceolate to narrowly elliptic, 5-15 × 2-4 cm, thin, abax­ially sericeous, adaxially glabrous, base cuneate, apex obtuse and mucronate. Racemes terminal or leaf-opposed, to 30 cm, 20-30-flowered; bracts linear, 1-2 mm. Bracteoles similar to bracts but shorter. Calyx 2-lipped, 1-1.5 cm, pubescent; lobes lanceolate-triangular, ± as long as tube. Corolla deep golden yellow; standard suborbicular to elliptic, 1.5-2 cm, base with 2 appendages, apex retuse; wings 1.5-1.8 cm; keel rounded through 90°, narrowed apically from middle and extended into a long twisted beak exserted beyond calyx. Ovary glabrous. Legume oblong, 4-6 × ca. 1.5 cm, 20-30-seeded; stipe ca. 5 mm. Fl. May-Sep, fr. Aug-Dec.

Baker (Fl. Brit. India 2: 75. 1876) suggested that Crotalaria sericea N. L. Burman (Fl. Indica, 156. 1768) might be conspecific with this species. If this was the case, then Burman’s name would have priority, but there seems to be too much doubt as to the exact identity of Burman’s species to justify displacing a well-established name. Some authors have cited Burman’s name as a synonym of C. assamica in the apparent belief that C. sericea N. L. Burman was a later homonym of C. sericea Retzius (1788), following Candolle who published the replace­ment name C. burmanii Candolle, but this is not correct as Burman’s name has priority.

Montane grasslands, along trails; below 100-3000 m. Guangdong, Guangxi, Guizhou, Hainan, Taiwan, Yunnan [India, Laos, Myanmar, Philippines, Thailand, Vietnam].