Washington State Weeds

Himalayan Knotweed

Himalayan Knotweed

Polygonum polystachyum

Family Name:

Polygonaceae

Class: B
Other Names: bell-shaped knotweed
 Why is it a noxious weed? It grows vigorously into dense colonies that exclude native vegetation, alters natural ecosystems and is difficult to eradicate. It poses a significant threat to riparian areas, where it can survive severe floods. Small fragments can form new plants.

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