(Fallopia japonica)

Name and Family

Japanese Knotweed (Fallopia japonica)


Japanese Knotweed was originally imported from Japan to North America as an ornamental garden plant. Since its arrival it has spread throughout Canada. In PEI it can be spotted along trails, in gardens and along roads. Urban areas are especially prone to invasion by Japanese Knotweed.

Identification Guide

Here are some key features that may help to positively identify Sycamore Maple:

  • Leaves are medium to large, broad, with a leathery texture, dark green above and light green below
  • Leaves have 5 lobes, with 2 outer lobes reduced, base of leaf is heart-shaped
  • Leaf edge is coarsely toothed
  • Bark is scaly and regularly flakes off mature trees, revealing an orange inner bark
  • Twigs: zig zag, stout, leaf scar nearly surrounds the bud, buds are large and cone-shaped
  • Flowers are small, greenish, and bloom in the spring in long, drooping clusters
  • Trees produce winged seeds (samaras) the form in clusters

What it does in the ecosystem

Japanese Knotweed is one of the Global Invasive Species Database’s 100 worst invaders. It grows in a wide variety of habitats and tolerates a wide range of adverse conditions such as deep shade, high temperatures, salinity, and drought. It grows in dense thickets that shade out neighbouring species and spreads readily via underground rhizomes. Once established, it generally takes great persistence and several years to eradicate. Japanese Knotweed is widespread on PEI.


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