Shui Hong Huang Zi

Shui Hong Huang Zi is the dried mature fruit (achene) of Persicaria orientalis (= Polygonum orientale; Polygonaceae), a robust annual herb 1–2 m tall widespread across temperate to subtropical Asia along riverbanks, ditches and disturbed wet ground. Stems are stout, branched, conspicuously softly pubescent and often tinged red at swollen nodes sheathed by fringed ochreae. Leaves are alternate, broadly ovate, 10–25 cm long, with pointed apex, rounded to subcordate base and pubescent surfaces. The terminal racemes are dense, drooping, 3–12 cm long, with deep rose-pink to red minute perianths. Each flower yields a single shiny, biconvex, dark-brown to nearly black lenticular achene about 3 mm across.