About Phragmites


Invasive Phragmites is native to Eurasia and was first observed in Ontario along the St. Lawrence River in 1916 and later found at Walpole Island in Lake St. Clair in 1948.  Rapid expansion occurred during the 1990’s and this robust grass is now established in most Lake Erie and Lake Huron wetlands and is getting a foot hold in Lake Superior coastal habitats. In 2005, Agriculture and Agri-food Canada identified invasive Phragmites as the nation’s “worst” invasive plant.

Measuring Phragmites in the field

Photo: Janice Gilbert

What is Phragmites?

Invasive Phragmites is a tall, perennial, wetland plant. It is a subspecies known as Phragmites australis, and is closely related to the native species known as Phragmites americanus. It is an aggressively spreading plant which out-competes many native wetland plants including cattails (Typha spp.) willows (Salix spp.), alders (Alnus spp.) and buttonbush (Cephalanthus occidentalis) resulting in expansive mono-culture stands. Invasive Phragmitesthrives in disturbed habitats and is often the first to colonize a new area. It prefers areas of standing water, but the roots can grow to extreme lengths, which allows the plant to survive in low water areas.

Invasive Phragmites grows in dense stands which crowd out native vegetation, resulting in decreased plant biodiversity. Invasive Phragmites stands provide poor habitat and food supplies for wildlife, impacting species at risk. Stands of invasive Phragmites are composed of a high percentage of dead stems, which are dry and combustible, increasing the risk of fires. Invasive Phragmites can also negatively affect agriculture, lower property values, cause road safety hazards, and impact recreational activities such as swimming, boating, and angling.

Where is it found?

Invasive Phragmites is found in all of the lower 48 states in the United States and in all Canadian provinces and the Northwest Territories. It has not been found in the Yukon or Nunavut. In Ontario, it has been identified across the southern part of the province with scattered occurrences as far as Georgian Bay and Lake Superior.

Map of where Phragmites is found in North America

Image courtesy of U.S. Department of Agriculture.



Invasive Phragmites colonizes wet areas including natural wetlands and shorelines. It prefers standing water, but the roots can grow to extreme lengths to allow the plant to survive in low water areas. It also thrives in disturbed habitats such as roads, ditches and agricultural areas, which has been attributed to a tolerance of a variety of environmental conditions including high salinity, nutrient and heavy metal levels. Roads and ditches are frequently disturbed areas with high inputs of salt and other contaminants, creating an optimal environment for Phragmites. Agricultural areas are also frequently disturbed areas with high levels of nutrients from fertilizer run-off.

Invasive Phragmites in Ontario

Invasive Phragmites has become a common site along Ontario’s major highways and secondary roads which act as spread vectors. Within the Lake Erie, Lake Huron and Huron/Erie Corridor coastal ecosystems, where Phragmites is particularly extensive, the impacts have the potential to be cumulatively devastating for a number of Species at Risk (SAR) which depend upon these habitats for all or a portion of their life cycle. Effective control options for expansive, well established cells are limited in Canada and nonexistent when surface water is present.

Quick Facts:

  • can grow up to 15 feet tall
  • can spread over 10 feet per year
  • produces toxins from its roots which impedes the growth of native plants, and can even kill them
  • is often confused with native Phragmites (learn to properly identify the plant before undertaking control)
  • seeds and/or plant parts are spread by wind, water, animal, and human movement (i.e. boats, trailers, ATVs, construction equipment