Gou Teng

Uncaria rhynchophylla is an evergreen woody climbing liana in the family Rubiaceae, native to the broadleaved evergreen forests and forest margins of southern China, Taiwan, Japan, Korea, and parts of Southeast Asia. The plant climbs by means of paired, recurved, hooklike modified peduncles that develop in the leaf axils, giving rise to the common name gambir hook. Mature vines can extend 10 m or more, with slender greyish-brown stems bearing opposite, ovate-lanceolate leaves 5-12 cm long that are glabrous above and slightly pubescent on the veins beneath. Small yellowish flowers are densely packed into solitary, globose terminal heads about 2-3 cm in diameter, blooming in summer. The fruits are small capsules with winged seeds adapted to wind dispersal. The medicinal portion comprises the hook-bearing stem segments collected from older vines.