Phragmites in Ontario

Invasive Phragmites (European common reed) is an invasive plant causing damage to Ontario’s wetlands.

What are invasive species?

Some of the plants and animals found in Ontario are not native to the province. Many of these species are harmless and may provide benefits such as food or recreational opportunities. Others, however, threaten the environment, Ontario’s economy, society, or human health. These harmful species are known as invasive species..

Invasive species have been introduced to Ontario’s lands and waters in the discarded ballast water from cargo ships and through the import of goods from other parts of the world. Invasive species often lack natural predators in their new surroundings, adapt easily to a range of environmental conditions, and reproduce at a rapid rate. These characteristics allow invasive species to quickly establish themselves in their new habitats. There are over 185 non-native species in the Great Lakes basin, including invasive species such as purple loosestrife and zebra mussels.

Invasive species can disrupt ecosystems and cause harm and stress to native species, including species at risk. Invasive species can alter food webs, affect nutrient cycling, and displace native species. These changes are often irreversible and can result in decreased biodiversity.

What is Phragmites?

Phragmites australis subspecies australis (also known as the European common reed) is an invasive perennial grass that has caused severe damage to wetlands and beaches in Ontario for several decades. It is unclear exactly how invasive Phragmites (pronounced “frag-my-teez”) was transported to North America from its native home in Eurasia. In 2005, it was identified as the nation’s “worst” invasive plant species by researchers at Agriculture and Agri-food Canada. Despite this designation, invasive Phragmites is still sold as an ornamental plant in some garden centres. 

5.2 metre tall Phragmites stand. Photo: J.M. Gilbert.

Invasive Phragmites is a very aggressive plant that spreads rapidly and outcompetes native species for water and nutrients. This invasive species thrives in disturbed habitats and is often among the first species to colonize these areas. Invasive Phragmites has an intricate system of specialized roots that secrete toxins into the soil to impede the growth of and kill neighbouring plants. While invasive Phragmites prefers areas of standing water, its roots can grow to extreme lengths. These roots can also extend deep into the soil to find and access moisture, allowing the plant to survive in relatively dry areas.

Stands of invasive Phragmites reproduce primarily through the extension of runners or through the dispersal of root fragments that readily grow into new plants. Root fragments can be transported by flowing water or winds or moved around by animals. Human actions, such as the horticultural and agricultural trades or the movement of boats, trailers, and ATVs, can also disperse root fragments. Once it is established, a new invasive Phragmites plant can grow several metres in height and produce up to 2000 seeds every year.

Invasive Phragmites is closely related to the native subspecies Phragmites australis subspecies americanus. Generally, native Phragmites does not grow as tall or as densely as the invasive subspecies and does not outcompete other native species. Invasive Phragmites stands are extremely dense, with up to 200 stems per square metre, and individual plants can grow up to 5 metres tall. Stands of invasive Phragmites can grow so densely that they crowd out other species whereas native Phragmites grows mixed with other plants. (Figure 1).

An invasive Phragmites stand has stems that are tan or beige in colour with blue-green leaves and large, dense seedheads. Native Phragmites has reddish-brown stems, yellow-green leaves, and smaller, sparser seedheads (Figures 2, 3, and 4). A number of characteristics should be looked at to decide if the species is a native variety. In some cases, genetic analysis may be necessary to determine if the invasive subspecies of Phragmites is present. 

Figure 1. A native Phragmites stand (left) and an invasive Phragmites stand (right). Note the varied vegetation and lower density of native Phragmites stems on the left, and the   taller, higher density of invasive Phragmites stems on the right. Photo: Erin Sanders and J.M. Gilbert.	Figure 2. A native Phragmites stem (left) and an invasive Phragmites stem (right). Note the reddish-brown native stem on the left and the tan/beige invasive stem on the right. Photo: Erin Sanders and J.M. Gilbert.

Figure 3. A native Phragmites leaf (bottom) and an invasive Phragmites leaf (top). Note the yellow-green colour of the native Phragmites leaf compared to the blue-green colour of the invasive Phragmites leaf.  Photo: Erin Sanders.	Figure 4. A native Phragmites seedhead (top) and an invasive Phragmites seedhead (bottom). Note that the native Phragmites seedhead is smaller and sparser compared to that of the invasive Phragmites. Photo: Erin Sanders.