Knock, Knock! Who is there? Japanese Knotweed!

japanese knotweed edible, invasive weed

japanese knotweed edible, invasive weed

Japanese knotweed (Polygonum cuspidalum), one of the most aggressive invasive weeds from eastern Asia, was introduced to the United States as an ornamental and now randomly pops up in the most unexpected places. The plant is an herbaceous perennial from Buckwheat (Polygonaceae) family. It has hollow stems with distinct raised nodes similar to bamboo. The plant can grow 3–4 meter tall. The leaves are broad oval with a truncated base, 7–14 cm long and 5–12 cm broad, with an entire margin. The small cream or white flowers are clustered on racemes 6–15 cm long in late summer. The plant is extremely difficult to eradicate- it survives wide range of conditions. Its rhizomes can survive temperatures of −35 °C (−31 °F) and can extend 7 meters horizontally and 3 meters deep. Established populations are extremely persistent and pose a significant threat to riparian areas.
Food: Young shoots of Japanese knotweed are plump and juicy with reddish-colored sheath and triangular leaves and are delicious edible treat. Young plant tastes like sorrel, the shoots are high in antioxidant Resveratrol, which helps to lower bad cholesterol and prevent heart attacks. The plant is an excellent source of vitamin A, vitamin C, the antioxidant flavonoid Rutin, potassium, phosphorus, zinc, and manganese. (Brill) It’s close relative, Giant Knotweed, is a lager variety, and is also edible. No poisonous lookalikes has been reported.
Medicine: In traditional Chinese medicine, it is known as Huzhang or “tiger stick.” As a concentrated source of resveratrol, the plant has anticancer, anti-inflammatory, blood sugar-lowering and other beneficial cardiovascular effects. (Elliott P.J.) Resveratrol may delay the onset of Alzheimer’s disease or slow its progression. Also, it activates sirtuin genes, which increase cell longevity the same way a calorie-restricted diet does. (Brill)
The roots of Japanese knotweed are used in traditional Chinese and Japanese herbal medicines as a natural laxative. The active ingredient responsible for the laxative effect is emodin, effective in doses of 20 to 50 mg per day.

Sources: For current distribution map visit
“Micronutrient Information Center: Resveratrol”. Linus Pauling Institute at Oregon State University.


About Anya Pozdeeva, vifarms

Vertically Integrated Urbarn Aquaponics, Permaponics, Permaculture and Sustainable Living, New York Style!
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