Cao Guo

Lanxangia tsao-ko, formerly Amomum tsao-ko and known in Chinese medicine as Cao Guo, is a robust, tufted perennial rhizomatous herb in the Zingiberaceae, native to the warm-temperate mountain forests of southwestern China, northern Vietnam, Laos and Myanmar. The plant forms dense clumps 2 to 3 meters tall from a thick, branching, aromatic rhizome. The leaf-bearing pseudostems are erect and bear two ranks of large, oblong-lanceolate leaves 40 to 70 cm long and 10 to 20 cm wide, with parallel venation and a strongly aromatic sheath. Separate, short flowering shoots arise directly from the rhizome at ground level, bearing a dense spike of pale yellow or orange tubular flowers with red-streaked labella. The fruit is an ovoid to ellipsoid, three-locular capsule about 2 to 4.5 cm long, with a thick, longitudinally ridged red-brown to greyish pericarp enclosing many irregularly polygonal, intensely camphoraceous seeds embedded in pulp. The dried mature fruit is the medicinal drug.