Reynoutria japonica
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Japanese knotweed (Polygonum cuspidatum, syn. Fallopia japonica, Reynoutria japonica) is a large, herbaceous perennial plant, native to eastern Asia in Japan, China and Korea.
A member of the family Polygonaceae, Japanese knotweed has hollow stems with distinct raised nodes that give it the appearance of bamboo, though it is not related. While stems may reach a maximum height of 3–4 m each growing season, it is typical to see much smaller plants in places where they sprout through cracks in the pavement or are repeatedly cut down. The leaves are broad oval with a truncated base, 7-14 cm long and 5-12 cm broad, with an entire margin. The flowers are small, creamy white, produced in erect racemes 6-15 cm long in late summer and early autumn.
Closely related species include "Giant knotweed" (Polygonum sachalinense) and "Russian vine" (Polygonum aubertii).
Cultivation and naturalisation
It was first introduced to Europe and North America in the late 19th century. Where it has been introduced, Japanese knotweed is typically considered an invasive plant or weed. It is a frequent colonizer of temperate riparian ecosystems, roadsides and waste places; the monocultures that often form following Japanese knotweed invasions contribute to reductions in native biodiversity. In the United States, it can now be found in 40 of the states. In Canada, it occurs in six provinces. The species is a frequent invader in Europe, including the U.K. where it was made illegal to spread Japanese knotweed by the Wildlife and Countryside Act 1981.
Japanese knotweed flowers are valued by some beekeepers as an important source of nectar for honeybees, at a time of year when little else is flowering. Japanese knotweed yields a nice monofloral honey, usually called "bamboo" honey by northeastern U.S. beekeepers, that is like a mild-flavored version of buckwheat honey (a related plant also in the Polygonaceae).
The young stems can be used as a spring vegetable similarly to asparagus.
Other English names for Japanese knotweed include Fleeceflower, Huzhang (Chinese: 虎杖; pinyin: Hǔzhàng), Hancock's curse, Donkey rhubarb (although it is not a rhubarb), Japanese bamboo, and Mexican bamboo (nor is it a bamboo).
Both Japanese knotweed and Giant knotweed are sources of Resveratrol.
External links
- Recipes from "Wildman" Steve Brill
- Strategies for the Eradication of Japanese Knotweed An introduction to Japanese knotweed and the strategies used by homeowners to eradicate it.
- Knotweed profile from invasivespecies.gov
- Japanese Knotweed (Polygonum cuspidatum) - A Noxious Weed in Washington
- Knotweed page on KnottyBits.com
- http://www.cabi-bioscience.org/html/japanese_knotweed_alliance.htm