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Japanese Knotweed

(Polygonum cuspidatum)
Polygonaceae Family

Japanses Knotweed & the Arboretum

Japanese Knotweed is the most detrimental invader in the Frostburg State University arboretum. In a few short years, it has managed to colonize almost the entire riparian area in the arboretum and has subsequently choked out several native plant species.

shade cloth image Currently, the Allen HallSTARS!, the Biology Department, The Wildlife Society, and other students, faculty, and staff have been working together to remove this invasive plant. Efforts to rid the arboretum have included cutting and burning the stalks, using shade cloth to inhibit growth, and dripping herbicide into cut stems. Since it is an intense nutrient competitor and has an extensive rhizome system, knotweed can withstand many treatments.

Our goals are to eventually "starve" out the root systems in order to kill the plants. Complete eradication of the knotweed may not be possible, but hopefully it will be kept under control.

More about Japanese Knotweed

Japanese Knotweed


  • Large, herbaceous perennial
  • Small, white flowers in clusters
  • Alternate, broadly ovate leaves
  • Thick, reddish, and jointed stems

Native Distribution

Japan, Northern China, Taiwan, Korea

Current Distribution

Europe, British Isles, United States, Canada, Newfoundland, New Zealand


Japanese Knotweed was first introduced in the United Kingdom and the United States as an ornamental plant from Japan in 1825. Since then, knotweed has rapidly spread vegetatively by cuttings or pieces of rhizomes. Ecologically, Japanese Knotweed is a dominant pioneer in volcanic areas in Japan. Because of this, knotweed is able to withstand adverse soil and environmental conditions. This adaptation has allowed knotweed to become an intense competitor which can rapidly grow and choke out all competition, including native plants.


  • Rapidly grows and produces monoculture stands
  • Chokes out native vegetation
  • Reduces biodiversity
  • Damages sidewalk and pavement

Japanese Knotweed