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Lakes in King County, Washington

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King County, Washington lakes

Reed canary grass
(Phalaris arundinacea)

Class C Noxious Weed

Reed canary grass History

Reed canary grass is likely to have been introduced from Eurasia, as were most of our weedy grasses. Considered a good forage plant in Sweden as early as 1749, it has been used for pasture, silage, and hay as well as filtration for water pollution control. The seed is used for birdseed.

Method of spread

This grass is an aggressive invader of moist areas, meadows and lake shores. Reed canary grass is a generally competitive, persistent and vigorous perennial grass that grows in poorly drained areas and along stream and canal banks. Its creeping rhizomes force out other grasses and thus reduce biodiversity. Although reed canary grass has been valuable for forage, it has become a threat to some of our native wetland plant communities. The grass is widely distributed in Idaho, Oregon, Nevada, Utah and Washington.

Methods of control

Reed canary grass can be handpulled, but because it does not tolerate shade the best control method is selective planting of favorable species. Once shaded, reed canary grass can be replaced by sedges, rushes, willow, red osier dogwood and chokecherry.


  • a coarse but attractive perennial, reed canary grass grows as tall as six feet
  • long leaves are flat, green with a sooty-gray hue, about 1/2 inch wide, and spread out from the stem at tight right angles
  • light green to straw colored stems have swollen stem nodes
  • flowers and grains grow in dense but branched clusters, which commonly turn purplish as the plant matures in spring and fade to straw color in late summer
  • roots spread extensively by creeping rhizomes and runners

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For questions about aquatic weeds and lakes in King County, please contact Sally Abella, senior engineer, Lake Stewardship Program.