Knotweed spreads vegetatively by rhizomes and also sprouts from fragments of root and stem material, which are dispersed by water, equipment or in fill. It forms fertile hybrids with giant Hybrid between giant and Japanese knotweed and shares characters of both parent species. established, Japanese knotweed is very difficult to eradicate. Japanese knotweed is an herbaceous perennial that forms large colonies of erect, arching stems (resembling bamboo). Plants reach up to 10’ and the dead stalks remain standing through the winter. Leaves are 4 to 6 inches long and pointed. Bashtanova et al. describe the plant as a perennial rhizomatous herb originating from Asia [1]. Japanese knotweed (Reynoutria japonica, Fallopia japonica or Polygonum cuspidatum) was originally introduced to the United States as an ornamental plant in the late 1800s and is now found in (at least) 39 states over a wide range of sites.Although considered extremely invasive, this plant however has edible shoots in Spring and roots that have been found to have medicinal value. Banks require a written management plan if it is present on or nearby property–and will not underwrite a mortgage without one. This article will assist with identification and provides recommendations for control, including a management calendar and treatment and timing table. Often confused with Japanese knotweed. Stems are round, smooth and hollow with reddish-brown blotches. Japanese knotweed (Polygonum cuspidatum) The most ornamental of the knotweeds and shorter than Bohemian or giant. Whether discharging a planning condition with one of our management plans or helping you to identify, survey and accurately plot any Invasive Species on your site, we’ve a vast amount of knowledge and experience to assist you from as early as the planning stage and beyond. Legislation: Northern Ireland; Under article 15 of the Wildlife (Northern Ireland) Order 1985, it is an offence to plant or otherwise cause to grow in the wild Japanese knotweed or any other invasive plant listed in Part II of schedule 9 to that Order. Bohemian knotweed (Polygonum x bohemicum) The most common invasive knotweed in western Washington. Japanese Knotweed, scientifically known as Fallopia japonica, is an Asian plant with a reputable ethnobotanical value among the Japanese.However, outside Asia, F. japonica is an invasive plant that ranks among the 100 worst invasive species as per IUCN. https://extension.unh.edu/blog/invasive-spotlight-japanese-knotweed In the United Kingdom, sellers have to disclose the presence of Japanese knotweed on deeds. The Global Invasive Species Database lists Japanese knotweed on its “100 of the World’s Worst Invasive Alien Species” list. Japanese knotweed (Fallopia japonica) is an invasive perennial and noxious weed in PA. Invasive, Exotic Plants of the Southeast Japanese Knotweed . Japanese knotweed is a non-native invasive plant that was introduced from Asia as an ornamental plant. Japanese Knotweed. Knotweed in Britain routinely cracks the pavement in roads, causes damage to retaining walls and building foundations, and lowers property values. 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