Phragmites australis is a native grass that grows in wetlands and wet areas. Also known as common reed, the grass is topped with creamy-brown feathery plumes and can grow up to 15 feet tall. It occurs in every continent except Antarctica and may have the widest distribution of any flowering plant.
In Washington, the earliest record of phragmites is from Klickitat County in 1882. Studies of peat samples show phragmites has grown in New England tidal wetlands for at least the last 3,000 years; the remains of the grass have been found preserved in the dung of the Shasta ground sloth, dating back 40,000 years. In the 1990s, some land resource managers proposed listing phragmites as a noxious weed because the species appeared to be aggressively invading wetland areas. At that time, the Washington Noxious Weed Control Board opted against listing it as a noxious weed because it was a native species. The board speculated that phragmites’ invasive behavior reflected its ability to take advantage of altered environmental conditions and disturbed landscapes.
By 2000, phragmites’ rapid colonization of wetland mitigation sites along the Snake River, and the displacement of native wetland vegetation prompted increased concern about this species. On the East Coast, some scientists began to speculate that the aggressive nature of phragmites might be due to an introduction of non-native genotypes. This theory spurred research to determine whether differences in genotypes existed among North American phragmites stands. A Yale University study concluded that aggressive, non-native genotypes of phragmites (perhaps introduced in the late 19th century) could overtake and displace native genotypes of phragmites and other native wetland species. The Yale study and confirmation of the presence of non-native phragmites in Washington–and the fact that invasive species had encroached on wetlands–called for prompt action.
In 2003, the Noxious Weed Control Board listed the non-native genotype of phragmites as a Class C noxious weed because its distribution in the state was unknown. In 2003, the Washington Department of Agriculture received an Aquatic Weeds Program grant (courtesy of the Washington Department of Ecology) and began surveying phragmites populations to determine the distribution of the plant throughout the state. Agriculture staff relied on morphologic differences between the genotypes and DNA analysis to confirm Washington populations as native or non-native genotypes. Native populations of phragmites on the East Coast have nearly vanished as the result of competition from non-native genotypes and land development.
In Washington, as more has become known about the distribution of phragmites genotypes, the Noxious Weed Control Board has taken steps to manage the non-native genotype. The board has done so by upgrading the classification of the non-native genotype from a Class C noxious weed (no mandate for control) to a Class B noxious weed (a weed designated for control). In other states the non-native genotype has displaced the native genotype. In Washington, an increased mandate for management of the non-native genotype of phragmites will help protect stands of the native genotype and other native wetland species.