Annual creeper growing to 20 in (50 cm). Has lance-shaped leaves and clusters of small pink or white flowers.
Habitat & Cultivation
Knotgrass is found in temperate regions throughout the world. It thrives on waste ground and along shorelines. The plant is gathered throughout the summer.
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 conditions—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.
See also bistort (P. bistorta), and he shou wu (P. multiflorum).