苏木 su mu

Trees, small, to 6 m tall, ± puberulent except on old branches and legumes. Branches with dense, conspicuous lenti­cels. Leaves 30-45 cm; pinnae 7-13 pairs, opposite, 8-12 cm; leaflets 10-17 pairs, closely spaced, sessile, oblong to oblong-rhombic, 1-2 cm × 5-7 mm, papery, both surfaces glabrous or sparsely hairy, lateral veins slender, conspicuous on both sur­faces, contiguous near margin, base oblique, inserted at oblique angles to rachis of pinnae, apex retuse or rounded. Panicles ter­minal or axillary, ca. as long as leaves; bracts caducous, lan­ceolate, large. Pedicels ca. 1.5 cm, puberulent. Receptacle shal­lowly campanulate. Sepals 5, slightly unequal, lower one larger than others, cucullate. Petals yellow, broadly obovate, ca. 9 mm, uppermost one entire at apex, tinged pink at base, clawed. Stamens slightly exserted; filaments densely pubescent at lower part. Ovary grayish velutinous, stalked, 3-6-ovuled; style slen­der, hairy; stigma truncate. Legume reddish brown, shiny, slightly compressed, suboblong to oblong-obovoid, ca. 7 × 3.5-4 cm, woody, attenuate to base, apex obliquely truncate, upper margin with a sharp beak. Seeds 3 or 4, light brown, slightly compressed, oblong. Fl. May-Oct, fr. Jul-Mar. 2n = 24.

Cultivated in Fujian, Guangdong, Guangxi, Guizhou, Hainan, Si­chuan, Taiwan, Yunnan [native origin unknown; Cambodia, India, Laos, Malaysia, Myanmar, Sri Lanka, Vietnam; Africa, America].

The heartwood contains a red dye and is used medicinally to re­lieve pain.