扁轴木 bian zhou mu

Shrubs or trees, to 6 m tall, prickly, with smooth, green bark. Leaf rachis and stipules becoming spines; pinnae 1-3 pairs, clustered at spinescent, very short rachis of leaves; rachis of pinnae green, to 40 cm; leaflets obovate-elliptic to obovate-oblong or oblong, 2.5-8.5 × 1-3.5 mm. Racemes sparsely flow­ered. Flowers yellow; pedicels 1.5-1.7 cm; bracts lanceolate. Sepals oblong, ca. 6 mm, apex obtuse. Petals spatulate, apex rounded, uppermost longer, ca. 11 × 6 mm. Filaments villous at base. Legume 7.5-10.5 cm.

Cultivated in Hainan [native to tropical America; widely culti­vated in tropical regions of the world].