Invasive Phragmites

Invasive Phragmites

Invasive Phragmites

(Phragmites australis)


This perennial grass has spread rapidly in some of Ontario’s wetlands, crowding out many native species. The grasses grow in very dense patches and decrease biodiversity substantially. Its ability to outcompete native species comes partially from the toxins released by their roots, as this also prevents other plants from growing in proximity to them. Invasive Phragmites prefer wetland areas but they can also grow further inland as they can have very long roots, giving them the ability to reach water in dry areas. 

Invasive Phragmites closeup


It is not known when this invasive was brought to Ontario but it has spread throughout the US and most of southern Ontario. There are also isolated populations in Alberta, Manitoba and Quebec.

Impacts & Control

This species is listed as restricted in Ontario, so it is illegal to plant or possess it. There are herbicides that can be used to control Invasive Phragmites but they are nonselective, so native species would also be impacted by applications. There are Marsh Master vehicles that are being used to control the reed, they use large rollers which flatten the reeds, they also cut down the reeds and use the marsh masters to transport them away. 

Native Canadian Bluejoint
Native Canadian Bluejoint Closeup

Lookalike– There are native species of phragmites that look very similar to the invasive, however, there are a few characteristics to look out for. First, the native species will not grow as dense and have other species growing alongside it. Second. the native species is more reddish-brown on the stem and have smaller yellow-green leaves. See the comparison images to the right. Note the closeup images and how the invasive phragmites is much thicker at the top and it grows much taller.

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