(Fallopia sachalinensis), Bohemian knotweed (Fallopia x bohe-mica), and Himalayan knotweed (Polygonum polystachyum). Companies have been set up to eradicate it, laws have been written to remove it. What are they? However, it has distinctive characteristics. Invasive. It forms fertile hybrids with giant knotweed (Polygonum sachalininese). Invasive knotweed species are commonly found along roadsides and on stream banks but also may be present in yards, vacant lots, edges of fields, parks and many other places. 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. Knotweed spreads vegetatively by rhizomes and also sprouts from fragments of root and stem material, which are dispersed by water, equipment or in fill. Japanese knotweed has a bamboo-like appearance, with distinctive red and green stems. 7. Legal Status. However, less attention is paid to Himalayan … Invasive Non-native Species. Polygonum cuspidatum/Fallopia japonica. All four species are similar in appearance, biology, impacts, distribution, and methods of control and will be discussed under the general title of “knotweeds”. This plant is not as invasive as many of the other species and may be controlled with selective pruning. Help educate your community through personal contacts and in such settings as garden clubs and civic groups. Lesser Knotweed is most effective at the front of the border or as a ground cover in a cool, moist area. It is often transported to new sites as a contaminant in filldirt seeds, sometimes distributed by water, and carried to a lesser … It’s often used as a catch-all term to refer to all the invasive knotweed species. tall (15-30 cm) and 2 ft. wide (60 cm) or more. Some populations, Plants range in height from about 5 feet to more than 20 feet. Japanese Knotweed. 8. BIOLOGY & SPREAD Japanese knotweed spreads primarily by vegetative means with the help of its long, stout rhizomes. The invasive knotweed complex is a group of tall, rhizomatous, perennial plants in the Polygonaceae family. Knotweeds are one of the 100 worst invasive species as iden- Support public policies and programs to control invasive plants. Japanese knotweed is a non-native invasive plant that was introduced from Asia as an ornamental plant. invasive plants. Well-known examples are Japanese Knotweed, Rhododendron, Grey Squirrel and Mink. It has numerous upright clusters of small white flowers which develop into winged fruits. Japanese knotweed sketchbook study. This tenacious invasive forms monocultures in moist, well-drained soil and can grow up to 10 feet tall. Japanese knotweed is a tall plant, up to 2 or 3 m, that grows vigorously, and forms dense thickets. 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