Zao Jiao Ci

Gleditsia sinensis, the Chinese honey locust, is a deciduous tree of the family Fabaceae, native to central and eastern China, reaching 15 to 30 meters tall with a broad crown. The trunk and lower branches bear striking, stout, often branched thorns up to 16 cm long, which are modified woody stems arising from the bark; these are the part used as Zao Jiao Ci. The bark is grayish-brown and fissured. Leaves are once or twice pinnately compound, with 6 to 14 pairs of small, oblong leaflets. Inconspicuous greenish-white flowers are borne in slender axillary racemes in spring, followed by long, flat, leathery, dark brown pods that twist at maturity and contain hard, oily seeds. The thorns are collected year-round, sliced obliquely, and dried for medicinal use.