A perennial herbaceous plant with a thick, curved, obliquely growing rhizome, dark brown on the outside and brownish-pink on the inside. The stem, notable for its knotty structure and lack of branching, bears several large basal or lower leaves, 1–4 small stem leaves, and a large, dense, cylindrical spike-like inflorescence with pink flowers. It blooms in June and July.
It typically grows in clusters on floodplain wet meadows along rivers, waterlogged lake shores, wet shrubby meadows, and sparse spruce forests. It is found in the tundra, forest-tundra, and forest zones of the European part of Russia (thinning toward the northwest) and in Western Siberia. In Eastern Siberia and Central Asia, it is replaced by closely related species.
The rhizomes of Zmeyevik — Rhizoma Bistortae — are used. They are harvested in the fall or after flowering, when the plant is easier to locate; roots, stem remnants, leaves, and dying rhizome tips are removed, the rhizomes are cleaned of soil, quickly rinsed, and dried in ovens or drying chambers.
The rhizomes contain 15–25% mixed tannins, primarily of the pyrogallol group, with a smaller amount from the pyrocatechin group, as well as free gallic and ellagic acids. Starch is present as a ballast substance in significant amounts.
The pharmacopoeia also recognizes Polygonum carneum S. Koch, commonly known as red-meat snakeweed, which grows in the subalpine meadows of the Caucasus.
The rhizomes are used as an astringent. They are prescribed in the form of a decoction, tincture, or liquid extract for treating the mucous membranes of the mouth, gargling, and as an internal remedy for gastrointestinal disorders. They are included in stomach astringent herbal mixtures, in combination with alder cones, cinquefoil, burnet, or horse sorrel.
Decoction recipe: 20 g of rhizomes per 200 ml of water, boil for 20 minutes. Take 1 tablespoon 2–3 times a day, half an hour before meals.