18. Acacia farnesiana (Linnaeus) Willdenow, Sp. Pl. 4: 1083. 1806.
金合欢 jin he huan
Mimosa farnesiana Linnaeus, Sp. Pl. 1: 521. 1753; Vachellia farnesiana (Linnaeus) Wight & Arnott.
Shrubs or small trees, 2-4 m tall. Bark brown, rough. Branches numerous; branchlets zigzag, with small lenticels. Leaves 2-7 cm; stipules spinelike, spines 1-2 cm, shorter on short branchlets; leaf rachis villous, glandular; pinnae 4-8 pairs, axillary, 1.5-3.5 cm in diam.; leaflets 10-20 pairs, linear-oblong, 2-6 × 1-1.5 mm, glabrous. Heads 1-3, axillary, 1-1.5 cm in diam.; peduncles 1-3 cm, hairy; bracts at or near tip of peduncle. Flowers yellow, fragrant. Calyx ca. 1.5 mm, 5-toothed. Corolla ca. 2.5 mm, 5-toothed. Stamens ca. 2 × as long as corolla. Ovary cylindric, puberulent. Legume brown, straight or curved, turgid, subcylindric, 3-7 cm × 8-15 mm, glabrous, scarcely dehiscent, filled with a pith separating seeds from each other. Seeds several, brown, ovoid, ca. 6 mm. Fl. Mar-Jun, fr. Jul-Dec. 2n = 26, 52.
Cultivated in Fujian, Guangdong, Guangxi, Guizhou, Hainan, Henan, Sichuan, Taiwan, Yunnan, Zhejiang [native to tropical America; cultivated throughout the tropics].
This species is grown as a hedge plant and is used medicinally and for dyes and gums.