Common Name: Giant Knotweed
Alternate Names: Japanese bamboo, Sakhalin knotweed
Scientific Name: Polygonum sachalinense F. Schmidt ex Maxim. and hybrids, also Reynoutria sachalinensis (F. Schmidt ex Maxim.) Nakai
Related Species: Japanese knotweed (Polygonum cuspidatum Siebold & Zucc. synonyms Fallopia japonica (Houtt.) Ronse Decr.)
Any person, corporation, business or other retail entity distributing Japanese and/or giant knotweeds for sale within the state must have information directly affixed to the plant or container packaging that it is being sold with, indicating that it is inadvisable to plant this species within 100 feet of a water body or its designated flood plain, as defined by Minnesota Statute 103F.111, Subdivision 4. View Minnesota Noxious Weed Law for more information.
Giant knotweed is native to Asia and was imported to North America in the late 1800s as an ornamental. It was also planted for erosion control and as livestock forage. Since its introduction, giant knotweed has escaped cultivation and is classified as a serious invasive species in several states.
Giant knotweed can be found in various disturbed habitats with varying sun exposure. It can be found along roadsides and other right-of-ways, meadows, gardens, stream banks, and riparian habitats.
Rhizomes allow giant knotweed to spread quickly and aggressively, although seed production can also contribute to spread. Giant knotweed typically infests new areas through human intervention or transport of root fragments along stream environments especially during periods of flooding. Movement of soil from infested sites is another common way for giant knotweed to infest new areas. Because giant knotweed produces both male and female flowers, it can also serve as a pollen source for the equally invasive Japanese knotweed. View giant knotweed distribution in Minnesota.
Giant knotweed forms tall, dense thickets that shade out and displace native vegetation, degrade habitat for fish and wildlife, alter waterways, and facilitate erosion and flooding. Once established, it dominates native vegetation and is a significant problem in riparian areas where stream-side tree growth is greatly reduced. Research studies have also shown that giant knotweed produces allelopathic chemicals from its roots, which prevent other plant species from growing and competing with it.
MDA Noxious Weed Program
County Ag Inspectors