Quan Shen

Polygonum bistorta (syn. Bistorta officinalis), commonly known as bistort or snakeweed, is a perennial herb of the family Polygonaceae found across temperate Eurasia in damp meadows, streamsides, and montane grasslands. It grows 30 to 80 cm tall from a thick, twice-bent (S-shaped) rhizome that is dark brown externally and pinkish within. Basal leaves are long-stalked, oblong to ovate-lanceolate with a truncate or somewhat decurrent base, while stem leaves are smaller and clasping. From early to midsummer, dense cylindrical terminal spikes of small pink to pale rose flowers are borne on erect, unbranched stems. The rhizome is exceptionally rich in tannins, which underlie its long-recognized astringent properties in both Chinese and European herbal traditions.