Japanese Knotweed (Polygonum cuspidatum)

click to expand
Japanese Knotweed
Woody perennial, up to 10’ tall. Common along streams and moist soils along roadsides.

  • Stems are bamboo-like.
  • Flowers are small and white, in plume-like clusters.
  • Blooms in late summer, from August into fall.
The Problem:
Plants spread primarily by underground stems (rhizomes) 20+ ft. in length from which new colonies emerge. Out-competes riparian vegetation that supports insects important to native brook trout and other species; reduces nesting areas of stream-dependent birds. Extremely difficult to eradicate due to extensive root system.