Common reed (Phragmites australis) is an invasive, perennial grass commonly found in wetlands, marshes, river edges, lakes, ponds, roadsides, and ditches. With unknown origins, this non-native vegetation is believed to have entered North America in the early 1800s from contaminated ballast water. Since its introduction to the U.S., common reed has spread to all states except Alaska, threatening native ecosystems by reducing biodiversity, increasing fire hazards, and outcompeting native plants. In 2003, Washington State listed common reed as a class B noxious weed. Here is how you can identify and reduce the impacts of common reed in your area!
How to Identify
Growing up to 20 feet tall, common reed has rough, hollow stems that appear green with yellow nodes in warmer months, turning completely yellow during the winter. The leaves grow up to 20 inches long on one side of the stem, taking on a bluish green coloration. Common reed blooms in late June to August with purple to gold bushy panicles of flowers. This plant grows in monotypic stands within wetlands and are commonly mistaken for native populations of Phragmites and other tall grasses containing plumes. Native Phragmites can be identified by their red to purplish steam and leaf sheaths that are easily removable, contrasting the color and density of common reed
Common reed spread vegetatively and through seed dispersal by wind and water. This species produces thousands of seeds per year and has an extensive rhizome system with sprouts deriving from just a small piece of rhizome. Common reed has a broad environmental tolerance, thriving in sunny environments with fresh, stagnant water. Once established, roots can grow up to 3-feet deep.
Common reed has a devastating impact on native ecosystems because of its wide tolerance to environmental conditions and ability to outcompete native subspecies for available resources, reducing biodiversity. The thick stands are unsuitable habitat for wildlife that rely on diverse ecological conditions to survive. In addition, the high biomass of this species increases fire potential, putting wildlife and humans at risk. Common reed may also alter wetland hydrology, as dense stands inhibit water circulation negatively affecting water quality.
There are many methods to eradicate or prevent the spread of common reed. Cleaning off machinery such as boats and trailers can prevent the spread of attached rhizomes. For established vegetation, herbicide control, prescribed burns, and manipulating water levels around plants may decrease populations. The Washington State Noxious Weed Control Board also provides resources for weed management to maintain sustainable ecosystems across the state.