Snake knotweed

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Snake knotweed
Snake knotweed (Bistorta officinalis), inflorescences in full bloom

Snake knotweed ( Bistorta officinalis ), inflorescences in full bloom

Nuclear eudicotyledons
Order : Clove-like (Caryophyllales)
Family : Knotweed family (Polygonaceae)
Subfamily : Polygonoideae
Genre : Knot oak ( Bistorta )
Type : Snake knotweed
Scientific name
Bistorta officinalis

The snake knotweed ( Bistorta officinalis Delarb. , Syn . : Persicaria bistorta ( L. ) Samp. , Polygonum bistorta L. , Bistorta major S.F. Gray ), also called meadow knotweed , is a species of plant belonging to the knotweed family (Polygonaceae ) heard.

This species with a snakelike red base axis is also called serpentine and (red) natterwur , although dragon arum and other arum plants were or are under this name . This plant species is popularly known as the “toothbrush” because of the shape of the inflorescence. Because of its similarity to a chive flower, the plant is also called "leek". In Saxony, but also in the Harz, the plant is known under the name “Otter's Tongue” and was used as a substitute for spinach or in soups during times of war.


The snake knotweed is a perennial herbaceous plant that reaches heights of 20 to 100 cm with upright, unbranched stems . The strong rhizome is s-shaped, serpentine, from which the German trivial name is derived. The leaf blade of the basal leaves is oval to oblong and up to 15 cm long. The top of the leaves is dark green, the underside bluish green.

The pink flowers are 4 to 5 mm long and stand in dense cylindrical false spikes that are about 2 to 7 cm long. The flower has eight stamens and three styles. The nuts are triangular.

The knotweed flowers from May to July. Fruit ripening is from August to September.

The number of chromosomes is 2n = 48, less often 44 or 46.


This plant species is almost circumpolar (within a climatic zone on several continents). Their range includes Europe, the temperate zones of Asia, Morocco and Pakistan. In North America it is a neophyte . In Europe, this species is largely absent in Scandinavia . In the south it is only represented in the mountains. In the Allgäu Alps in Bavaria, it rises at the summit of the Riedberger Horn up to an altitude of 1785 meters.

Locations are moist humus soils that are rich in nitrogen and mineral compounds . They are mainly found in wet meadows in the lowlands up to the alpine level. The snake knotweed is a character species of the Calthion association in Central Europe, but also occurs in societies of the Adenostylion, Alno-Ulmion or in the mountains of the Polygono-Trisetion association. It is one of the indicator plants for soil moisture.


The snake knotweed is a semi-rosette plant. The flowers are strictly pre-male "bluebells with sticky pollen". The flower scent probably comes from the pollen putty. Insect visits are abundant, especially bees . Self-pollination is largely excluded.

The small, 10 mg heavy nuts are spread out together with the flower cover as wind and animal shakers. Because of their airy cover, swimming also takes place, as does random spreading by ungulates . Vegetative reproduction takes place through the rhizome .

Snake knotweed serves as a source of food for the caterpillars of the iridescent blue fire butterfly and the ringed mother-of-pearl butterfly .

Shimmering blue fire butterfly on a snake knotweed inflorescence


The snake knotweed is a valuable fodder when fresh ; however, it becomes worthless in the hay because the leaves crumble.

The species is also used as a wild vegetable . The starchy roots, which also contain vitamin C , can be cut into thin slices and soaked in water overnight from September into winter and then eaten with leafy vegetables or processed as a patty. From April to August, the leaves can be used as a basis for lettuce, spinach or leafy vegetable dishes. Since all parts also contain a lot of oxalic acid and tannins , only small amounts should be consumed.

The thickened, snake-shaped rhizome was previously used as a remedy (sometimes as a domestic substitute for Arum dracunculus or Dracunculus vulgaris ) and was used in the sense of the signature theory for snake bites. The name also refers to this connection.

More photos


Individual evidence

  1. a b Bistorta officinalis in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland.
  2. a b Erich Oberdorfer : Plant-sociological excursion flora for Germany and neighboring areas . 8th edition. Verlag Eugen Ulmer, Stuttgart 2001, ISBN 3-8001-3131-5 . Page 336.
  3. Erhard Dörr, Wolfgang Lippert : Flora of the Allgäu and its surroundings. Volume 1, IHW, Eching 2001, ISBN 3-930167-50-6 , p. 448.
  4. ^ KG Lutz (ed.): J. Storms Flora of Germany [...]. 15 volumes, 2nd edition Stuttgart 1900–1907, volume 4, p. 222 f.
  5. Walter Lawrence Wardale: The High German Bartholomäus. Critically commented text from a medieval pharmacopoeia based on the London manuscripts Brit. Mus. Add. 16,892, Brit. Mus. Arundel 164, Brit. Mus. Add. 17.527, Brit. Mus. Add. 34,304 [...] Ed. By James Follan, Dundee 1993, p. 38 f.

Web links

Commons : Snake Knotweed ( Bistorta officinalis )  - Album with pictures, videos and audio files