Knotweed Identification and Control
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This page is currently under construction. Come back soon for more information on how to identify and control knotweed, including instructional videos!
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Knotweed is fast growing and extremely aggressive. It invades river and creek banks, permanently displaces native vegetation, destroys critical fish and wildlife habitat, and reduces recreational opportunities.
After only a few years, it can be virtually impossible to control knotweed if left unchecked, so please ACT NOW by educating yourself.
Download the pdf here to learn how to help save Pacific Northwest rivers from knotweed! |
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Seasonal Guide to Identifying Japanese Knotweed
Knotweed is a bamboo-like perennial that grows in dense stands 6 to 12 feet tall. It has hollow, reddish cane-like stems with swollen stem nodes that are surrounded by thin papery sheaths. Leathery, spade-shaped leaves are arranged in an alternating pattern along the stems. The former popularity of Japanese knotweed as an ornamental shrub stems from their attractive flower clusters. These showy, plume-like clusters contain hundreds of small, creamy white to greenish white flowers and extend upward from the upper leaf axils. The fruits are 3-sided and papery, each containing one glossy dark seed.
At the end of the growing season, the plants die back to the ground. However, the dead reddish brown canes often persist throughout the winter.
At the end of the growing season, the plants die back to the ground. However, the dead reddish brown canes often persist throughout the winter.
