Knotweeds are one of the 100 worst invasive species as iden- Support public policies and programs to control invasive plants. It forms fertile hybrids with giant knotweed (Polygonum sachalininese). Invasive. All four species are similar in appearance, biology, impacts, distribution, and methods of control and will be discussed under the general title of “knotweeds”. Japanese knotweed is a tall plant, up to 2 or 3 m, that grows vigorously, and forms dense thickets. Polygonum cuspidatum/Fallopia japonica. Japanese knotweed has risen in prominence recently, you may have even read my 2018 blog post on the subject), it is often maligned by solicitors, surveyors and lenders as public enemy number one, and still regularly sees articles written in the mainstream media eg, The Telegraph (2019), The Independent (2019) and The Express (2019).. Japanese knotweed has a bamboo-like appearance, with distinctive red and green stems. Legal Status. BIOLOGY & SPREAD Japanese knotweed spreads primarily by vegetative means with the help of its long, stout rhizomes. Invasive Non-native Species. This plant is not as invasive as many of the other species and may be controlled with selective pruning. Some populations, However, it has distinctive characteristics. Knotweed spreads vegetatively by rhizomes and also sprouts from fragments of root and stem material, which are dispersed by water, equipment or in fill. 8. invasive plants. Grows up to 6-12 in. Well-known examples are Japanese Knotweed, Rhododendron, Grey Squirrel and Mink. Invasive non-native species (INNS) are species which have been introduced, as a result of human activity, to an area where they are not native, and which are detrimental to native species and habitats. It has numerous upright clusters of small white flowers which develop into winged fruits. This tenacious invasive forms monocultures in moist, well-drained soil and can grow up to 10 feet tall. What are they? Help educate your community through personal contacts and in such settings as garden clubs and civic groups. It is often transported to new sites as a contaminant in filldirt seeds, sometimes distributed by water, and carried to a lesser … Lesser Knotweed is most effective at the front of the border or as a ground cover in a cool, moist area. Japanese Knotweed. tall (15-30 cm) and 2 ft. wide (60 cm) or more. It’s often used as a catch-all term to refer to all the invasive knotweed species. (Fallopia sachalinensis), Bohemian knotweed (Fallopia x bohe-mica), and Himalayan knotweed (Polygonum polystachyum). Japanese knotweed is a non-native invasive plant that was introduced from Asia as an ornamental plant. Japanese Knotweed: The Invasive Plant That Eats the Value of Your Home By Christopher Middleton On 07/05/14 at 12:36 PM EDT A girl stands under a thicket of invasive Japanese knotweed. Companies have been set up to eradicate it, laws have been written to remove it. 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