However, as the name suggests, giant knotweed grows much taller (4-5 metres) and has much larger, elongated leaves. Regents of the University of Minnesota. Like Japanese knotweed, it was … Giant knotweed is the biggest of the three invasive knotweeds, with stems usually between 6 and 16 feet, but reaching as much as 17 feet tall is some areas. The plants die back at the end of the growing season but their old reddish-brown canes often persist. Giant knotweed is an herbaceous perennial that is woody in appearance and can grow over 10 feet tall. Identify Giant Knotweed Similar to Japanese knotweed, Giant knotweed is a seasonal plant that looks different depending on the time of year. 1. The University of Minnesota is an equal opportunity educator and employer. Species Assessment Groups (SAG) were assembled to recommend a legal classification for each species considered for NR 40. Giant Knotweed Invasive Species Alert - Printable PDF, Use the Midwest Invasive Species Information Network, http://www.misin.msu.edu/tools/apps/#home, Perennial, herbaceous shrub that can grow over 12 feet high, Hollow stalks are light green, smooth and swollen at the nodes, resembling bamboo, Similar to Japanese knotweed, and the two plants may hybridize, Flowers are arranged in spikes near the end of the stem are small, numerous, and greenish-white in color, Flowers do not extend past the length of the leaves, Flowers bloom in August and September in Michigan, Giant knotweed leaves are 6-14 inches long, heart-shaped at the base and have fine hairs on the underside. Japanese knotweed (Fallopia japonica syn. It has erect hollow stems that … The flowers are small, creamy white to greenish white, and grow in showy plume-like, branched clusters from leaf axils near the ends of the stems. It can be distinguished by its larger leaves and heart-shaped leaf bases. University of Minnesota Extension discovers science-based solutions, delivers practical education, and engages Minnesotans to build a better future. The stem nodes are swollen and surrounded by thin papery sheaths. Giant knotweed. They are large, reaching twelve inches across and six to fourteen inches wide. Click below on a thumbnail map or name for species profiles. Polygonum cuspidatum), an herbaceous perennial member of the buckwheat family, was introduced from East Asia in the late 1800s as an ornamental and to stabilize streambanks. Giant knotweed should be reported. © They form in clusters and bloom up from the leaf axil from July to October. Giant knotweed grows in disturbed areas and can tolerate varying sun availability. Keep these handy, perhaps in … Hybrid or Bohemian Knotweed Fallopia bohemica. Gallery: Common names: Japanese knotweed (Japanese bamboo, sally rhubarb, fleeceflower, and Himalayan fleece vine, Mexican bamboo, false bamboo) Giant knotweed (sacacline, sakhalin knotweed) Bohemian knotweed (Japanese-Giant hybrid) Scientific Name: Japanese knotweed: Fallopia japonica (syns. Simple, alternate, toothless and heart shaped. This species is considered a watch list species… Extension is expanding its online education and resources to adapt to COVID-19 restrictions. Himalayan knotweed … Giant knotweed has perfect flowers, including both female and male fertile flowers. Large, light green and hollow with reddish joints. Giant knotweed Giant knotweed (Fallopia sachalinensis) is larger than Japanese knotweed, often reaching 4m (13 ft) in height. – giant knotweed Subordinate Taxa. Giant Knotweed Japanese Knotweed Himalayan Knotweed Identification Flowers: All knotweed species, with the exception of Himalayan knotweed, have small, white/ green flowers that grow in showy, plumelike, branched clusters along the stem and leaf axils (joints). Description: Giant knotweed is an herbaceous perennial in the buckwheat family (Polygonaceae) that is woody in appearance and can grow over 12 feet in height. Print out an image of each species as a guide for identification. Reynoutria sachalinensis (giant knotweed or Sakhalin knotweed Japanese オオイタドリ ooitadori, Russian Горец сахалинский, Гречиха сахалинская; syns. The stems are smooth, hollow and light green, resembling the canes of bamboo, and sparingly branched. The stem nodes are swollen and surrounded by thin papery sheaths and male fertile flowers or in... 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