Su Mu

Caesalpinia sappan (syn. Biancaea sappan), sappanwood, is a small to medium-sized thorny tree of the family Fabaceae, native to Southeast Asia and southern China and long cultivated for both medicine and dye. It grows 5 to 10 meters tall, with grayish bark and recurved prickles on the branches and along the rachis of the leaves. The leaves are bipinnately compound with numerous small oblong leaflets. Showy terminal panicles of bright yellow, slightly irregular flowers with a red blotch appear in summer, followed by flat, woody, oblong pods that contain three to four hard seeds. The dense, deep red to orange-red heartwood, rich in brazilein and homoisoflavonoid pigments, is the medicinal and dye material, harvested from mature trunks and split into chips.