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Phragmites (or common reed) identification and control: Phragmites australis

Phragmites (or common reed) identification and control

Phragmites australis


Phragmites, a regulated Class B noxious weed, is a 12-foot-tall perennial grass found in wetlands, ditches, and similar habitats. Smooth, lance-shaped leaves grow 8-16 inches long on woody, rough, hollow stems. Tannish, purplish, plume-like flower clusters reach 1-16 inches long. This plant reproduces vegetatively and by seed. Both native and non-native strains grow in Washington, so be sure to get expert identification before taking any eradication measures.

Distribution and Impact

This tall wetland grass is also known as common reed. There are both native and non-native strains of this plant in Washington. Due to its aggressive tendencies and impact to waterways, the non-native strain or haplotype is a Phragmites found in both eastern and western Washington and some infestations are many acres in size. In King County, most infestations are still small and can be eradicated. Because native populations have been found in the region, careful identification by an expert is needed before any eradication measures are taken.

Phragmites Halotypes

phragmites infestation

The Washington State Department of Agriculture (WSDA) received a grant from Department of Ecology in 2003 to undertake a statewide phragmites project. The project began mapping all known locations of phragmites using GPS technology and to develop a GIS layer for the State. The researchers submitted samples from each site to Dr. Bernd Blossey at Cornell University for genotyping and input into his national database. All of the populations from King County were identified as the non-native haplotype. For more information on this project and how to distinguish the types of phragmites, check out Great Lakes Phragmites Collaborative.

Legal status in King County, Washington

Class B noxious weed in Washington, designated for control in King County. Because of the limited distribution in the county and the potential serious impact, control of phragmites is required in King County. For more information on noxious weed regulations and definitions, see Noxious weed lists and laws.

Additional information on phragmites

Phragmites photos

phragmites on Lake Sammamish
phragmites infestation

Report phragmites in King County, Washington

Locate phragmites in King County, Washington

Related information

Related agencies

Program offices are located at 201 S. Jackson St., Suite 600, Seattle, WA 98104. To contact staff, see the Noxious Weed Control Program Directory, send an email, or call 206-477-WEED (206-477-9333).