Japanese Knotweed (Fallopia japonica), is a large,herbaceous perennial plant, native to eastern Asia in Japan, China and Korea. In North America and Europe the species is very successful and has been classified as an invasive species in multiple countries.
A member of the family polygonaceae, Japanese knotweed has hollow stems with distinct raised nodes that give it the resembleance of bamboo, though it is not closely 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, cream or white, produced in erect raecemes 6–15 cm long in late summer and early autumn.
The English names for Japanese knotweed include fleeceflower, Himalayan fleece vine, monkeyweed, Huzhang, Hancock's curse, elephant ears, pea shooters, donkey rhubarb (however it is not a rhubarb), sally rhubarb, Japanese bamboo, American bamboo, and Mexican bamboo (although it is not a bamboo).
In the U.S. and Europe, Japanese knotweed is widely considered an invasive species or weed. It is listed by the World Conservation Union as one of the Worlds 100 worst invasive species list
The invasive root system and strong growth can damage foundations, buildings, flood defences, roads, paving, retaining walls and architectural sites. It can also reduce the capacity of channels in flood defences to carry water.