Japanese knotweed
(Fallopia japonica or Polygonum cuspidatum)
General description:
Japanese knotweed is an herbaceous perennial that forms large colonies of erect, arching stems (resembling bamboo). Stems are round, smooth, and hollow with reddish-brown blotches. Plants reach up to 10’ and the dead stalks remain standing through the winter.
Ecological threat:
- New infestations of Japanese knotweed often occur when soil contaminated with rhizomes is transported or when rhizomes are washed downstream during flooding.
- Poses a significant threat to riparian areas where it prevents streamside tree regeneration, and increases soil erosion.
- Root fragments as small as a couple inches can resprout, producing new infestations.
- Disrupts nutrient cycling in forested riparian areas.
- Plants contain allelopathic compounds (chemicals toxic to surronding vegetation).
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