Identification
Invasive Phragmites, also known as European common reed, is an invasive perennial grass known for its tall height (up to 5 meters). You’ve probably seen it growing in roadside ditches all over the region. It is similar in appearance to the native subspecies, American common reed, but has a few key distinguishing features. The foliage of invasive Phragmites is more blue-green in colour, it has tan stems, and the seed head plumes are much denser and purple in colour during the peak growing season. Native phragmites has foliage that is green-yellow, its stems have red/brown colouration, and the seed head plumes are comparatively sparse and tan in colour. Invasive and native Phragmites alike prefer to grow in damp or wet (aquatic) sites such as wetlands, and along the shores of lakes and streams. Native Phragmites will coexist well with other wetland plants, but invasive Phragmites often forms dense monocultures that leave no space for native plants. Invasive Phragmites is also commonly found in disturbed areas such as along roadsides, railways, utility corridors, and stormwater management features.
Impacts
Invasive Phragmites impacts people and the environment to such an extent that it has been named Canada’s worst invasive species. In Ontario, invasive Phragmites poses a threat to a quarter of our at-risk species. A Phragmites infestation in a wetland can significantly alter its physical and biological functioning. The extreme density of stems in a Phragmites patch prevents other plants from growing and makes it difficult for wildlife to access and use their habitat. Phragmites also release biochemicals into the soil to actively inhibit the growth of other plants. Phragmites patches are known to alter wetland hydrology. The densely grouped stems can inhibit flow, causing stagnation, and water levels are drawn down by high levels of transpiration.
Invasive Phragmites is a risk to people as well as the environment. Stands of invasive Phragmites growing along roadways can interfere with traffic sight lines, creating a hazard. The vigorous growth of its rhizomes can damage infrastructure such as asphalt and bridge abutments. When growing in storm water management ponds and other drainage features, Phragmites can alter the functioning of these systems by impeding flow and altering water levels. Dead, standing stalks of Phragmites pose a fire hazard as they can be easily ignited. Phragmites may also interfere with agriculture by encroaching on fields and crops.
Phragmites in the Cataraqui Region
Phragmites is widespread throughout Southern Ontario, and the Cataraqui Region is no exception. During our 2024 baseline inventory, the Cataraqui Phragmites Working Group identified over 740 distinct populations totalling more than 500,000 m2 in area (over 50 hectares). Phragmites was typically more common in areas of high disturbance, such as along major transportation routes and industrial areas. The Working Group hopes to reduce the amount of Phragmites in the region by launching a roadside control program in partnering municipalities and continuing to support landowners and community groups with small scale manual removal. If you want to learn more about what is being done to monitor and control Phragmites in the region, we encourage you to visit our Cataraqui Phragmites Management Area page. To see up-to-date information on the distribution of invasive Phragmites, visit: European common reed, Phragmites (Phragmites australis) - EDDMapS State Distribution - EDDMapS or, view our Cataraqui-specific webmap here: Phragmites Inventory
Source:
https://www.invasivespeciescentre.ca/
BMP_Phragmites_April302021_D10_WEB.pdf