Knotgrass plant, Bian Xu (Chinese) - Polygonum Aviculare (Polygonaceae)

Medicinal Use of Knotgrass, Bian Xu (Chinese) – Polygonum Aviculare (Polygonaceae)


Annual creeper growing to 20 in (50 cm). Has lance-shaped leaves and clusters of small pink or white flowers.

Habitat & Cultivation

Ā Knotgrass is found in temperate regions throughout the world. It thrives on waste ground and along shorelines. The plant is gathered throughout the summer.

Parts Used

Aerial parts.


Knotgrass contains tannins, flavonoids, polyphenols, silicic acid (about 1%), and mucilage.

History & Folklore

Knotgrass has been used as a diuretic in Chinese herbal medicine for over 2,000 years. In the Western tradition, the 1st-century CE physician Dioscorides likewise considered knotgrass to be a diuretic, as well as a remedy for heavy menstrual bleeding and snake bite.

Medicinal Actions & Uses

An herb with astringent and diuretic properties, knotgrass is used in European herbal medicine to treat many conditionsā€”diarrhea and hemorrhoids, to expel worms, to staunch bleeding wounds, to reduce heavy menstrual flow, and to stop nosebleeds.

Knotgrass is also taken for pulmonary complaints, since its silicic acid content strengthens connective tissue within the lungs. In Chinese medicine, it is given to expel tapeworm and hookworm, to treat diarrhea and dysentery, and as a diuretic, particularly when urination is painful.


Chinese research indicates that the plant is a useful medicine for bacillary dysentery. Of 108 people with this disease treated with a paste of knotgrass (taken internally), 104 recovered within 5 days. Results from Iranian laboratory studies indicate that knotgrass stimulates apoptosis (programmed cell death) and might be of use in treating breast cancer.

Related Species

See also bistort (P. bistorta), and he shou wu (P. multiflorum).