Du Zhong

Eucommia ulmoides is a medium-sized deciduous tree in its own monotypic family Eucommiaceae, native to central China and now cultivated in many temperate regions. It typically grows 15-20 meters tall with a straight trunk, greyish-brown furrowed bark, and a spreading crown. The alternate leaves are elliptic to ovate, 8-16 cm long, with acuminate tips and serrate margins; uniquely, when a leaf is torn slowly, fine, white, elastic threads of latex (gutta-percha) stretch between the broken halves. The tree is dioecious, with small inconspicuous petalless flowers appearing before the leaves in spring, followed on female trees by flat, winged samaras. In TCM, the inner bark (Du Zhong) is harvested from trees about ten to fifteen years old and used as a sweet, warm herb that tonifies the liver and kidneys and strengthens sinews and bones.