Description from Flora of China
Caesalpinia kwangtungensis Merrill; C. nuga (Linnaeus) Aiton; C. szechuenensis Craib; Guilandina nuga Linnaeus.
Climbers, woody, to 10 m tall. Bark blackish, with few recurved prickles. Leaves 20-30 cm; rachis with blackish recurved prickles; pinnae 2 or 3(or 4) pairs, opposite; leaflets 4-6 pairs, opposite, with short petiolules, adaxially shiny, ovate or elliptic, 3-6 × 1.5-3 cm, leathery, both surfaces glabrous, base broadly cuneate or obtuse, apex obtuse-rounded, sometimes emarginate, rarely acute. Racemes 10-20 cm, arranged in terminal, lax, large panicles. Flowers fragrant; pedicels 5-15 mm, slender. Sepals 5, lanceolate, ca. 6 mm, glabrous. Petals unequal: 4 yellow, ovate, glabrous, slightly conspicuously shortly clawed; upper one tinged with red stripes, attenuate to claw, inside hairy at central part. Stamens slightly extended; filaments inflated and hairy at base. Ovary hairy, 2-ovuled. Legume obliquely ovoid, 3-4 × 2-3 cm, swollen, leathery, reticulate, apex beaked. Seed solitary, compressed. Fl. Apr-Jul, fr. Jul-Dec. 2n = 24.
Mountain slopes, forests; 400-1500 m. Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hubei, Hunan, Sichuan, Taiwan, Yunnan [Cambodia, India, Indonesia, Japan (Ryukyu Islands), Malaysia, Myanmar, Papua New Guinea, Philippines, Sri Lanka, Thailand, Vietnam; Australia, Polynesia].