Ding Gong Teng

Ding Gong Teng is the dried stem of Erycibe obtusifolia Benth. or Erycibe schmidtii Craib (Convolvulaceae), woody, evergreen lianas of subtropical broadleaf forests of southern China (Guangdong, Guangxi, Hainan), Indochina, and Thailand. Stems climb 5–10 m, with brown, longitudinally fissured bark and a pale, sometimes streaked, woody cylinder showing characteristic radiating xylem rays on transverse section. Leaves are alternate, simple, leathery, elliptic to obovate, 6–15 cm long, with entire margins and a blunt or shortly acuminate apex. Inflorescences are axillary or terminal panicles of small, fragrant, white to pale yellow funnelform flowers; the fruit is a one-seeded ovoid berry 1–1.5 cm. Stems are harvested year-round, sliced, and dried. The principal alkaloid baogongteng A is a potent muscarinic agonist used clinically (eye drops) in China for glaucoma; internal use requires medical supervision due to cholinergic effects.