Japanese Knotweed

Genus: Polygonum

Species: cuspidatum

Description: Perennial that resembles bamboo and forms large clumps 1-3 meters (3-10 ft) high. Flowers are greenish-white and appear in summer.

Where it grows: Spreads primarily in along riverbanks and grows in wetlands, waste places and roadways.

How it spreads: Rhizome (underground stem) pieces are spread in fill dirt and water.

What it threatens: Its early growth period and height combine to shade out other vegetation and prohibit regeneration of other species. It reduces species diversity and damages wildlife habitat.

More information: 4 County Cooperative Weed Management Association

Disclaimer - Clean Water Services does not endorse or recommend specific herbicides for use in controlling these species. To protect water quality, always follow herbicide label directions and obey application laws when using any herbicide.