Guan Mu Tong

Aristolochia manshuriensis is a large, deciduous woody climbing vine of the Aristolochiaceae, native to the broadleaf forests of northeastern China, the Korean Peninsula, and the Russian Far East. Mature stems may reach 10–15 m, twining over trees with grey-brown, longitudinally fissured bark and a distinctive cross-section showing pith and broad radiating rays. Alternate, long-petioled leaves are broadly cordate to nearly orbicular, 15–30 cm across, soft and pubescent beneath. The bilaterally symmetrical, pipe-shaped flowers, 5–8 cm long, are yellowish-green with purple veining and emit a fetid odour to attract carrion-flies. The cylindrical capsule splits into six valves at maturity. The medicinal organ is the woody stem. The species contains aristolochic acids and is now banned or withdrawn from medicinal use in most jurisdictions because of severe nephrotoxic and carcinogenic risk.