City of Mississauga Parks and Forestry - Invasive Species

Invasive Species

Invasive species are plants and animals that have been introduced to our environment that present threats to our environment, the economy, our society or human health. Click on the titles below to learn more about non-native species in Mississauga.

Photo courtesy of Scott Sampson, Credit Valley Conservation

Buckthorn creates a dense thicket and spreads with help from birds and animals that eat the berries and release seeds in their droppings.

There are two invasive Buckthorn species: European and Glossy. European Buckthorn has thorns at the end of the branches, and both species have black fruit.

For more information, click here.

Dog-Strangling Vine
Photo courtesy of Rob Routledge, Sault College,

Dog-Strangling Vine is a densely growing vine that covers the ground and smothers native plants. The vines create a thick tangle on the ground or grow up on other plants up to 2 metres high.

Thin stems, oval, pointed leaves, narrow seed-pods and pink/purple, star-shaped flowers characterize this plant.

For more information, click here.

Emerald Ash Borer
Photo courtesy of David Cappaert,

Signs of Emerald Ash Borer (EAB) infestation in an ash tree can be seen as woodpecker holes or as small D-shaped exit holes in the tree bark.

For more information, visit

Garlic Mustard

Garlic Mustard was brought from Europe as an edible herb, but its prolific growth has allowed it to spread into many natural areas. In four years, a population can double in size.

This plant has small white flowers and its young leaves smell like garlic when crushed.

For more information, click here.

Giant Hogweed
Photo courtesy of Credit Valley Conservation

Giant Hogweed is a toxic perennial plant that generally grows along streans. A garden ornamental from Asia can grow up to 5.5 metres tall.

Call 3-1-1 to report sightings of Giant Hogweed.

For more information, click here.


Goutweed is a common garden plant as it creates dense ground cover. When it grows into natural areas, it covers the ground, smothers native plants and reduces biodiversity.

Goutweed can have a white and green leaf or a solid-green leaf with a small white flower.

For more information, click here.

Gypsy Moth

European Gypsy Moths were originally brought to North America to start a silk industry, but they escaped and started spreading through the forests of Eastern North America. In Mississauga, Gypsy Moth caterpillars mainly feed on Oak leaves.

The City has a program to monitor Gypsy Moth populations and protect City-owned oak trees.

Learn how you can help protect oak trees on your property, visit


Honeysuckle is an ornamental shrub native to Asia that spreads into natural areas by animals that eat the fruit and spread the seed.

There are many species of non-native Honeysuckle that can invade natural areas. This shrub is often multi-stemmed with oval leaves and red berries.

For more information, click here.

Japanese Knotweed
Photo courtesy of Leslie J. Mehrhoff, University of Connecticut,

Japanese Knotweed is a tall ornamental plant native to Asia.

Reaching heights up to 3 metres tall, this plant is often mistaken for bamboo and can be distinguished by its broad leaves. It is a persistent invader that spreads aggresively, forming dense patches.

For more information, click here.

Manitoba Maple
Photo courtesy of Paul Wray, Iowa State University,

Manitoba Maple grows in lowland areas, typically around creeks and rivers. This species out-competes native lowland trees and colonizes disturbed areas.

Unlike native maples, Manitoba Maple leaves are compound, i.e. they are composed of 3-9 leaflets on a central stalk.

Norway Maple

Norway Maple is a tree that grows well in cities, but it also grows well in natural areas and out-competes native trees.

This maple differs from native maple trees by its leaves that are wider than long, its milky-coloured sap and sometimes its leaf colour. For example, its 'Crimson King' variety has maroon-coloured leaves.

Photo courtesy of Leslie J. Mehrhoff, University of Connecticut,

Phragmites is native to Eurasia. It grows in wetlands and is often seen in ditches along roads.

A perennial grass reaching up to 5 metres tall, it contains tan-coloured stems and a large, fluffy seed head. Toxins are released from its roots to kill surrounding plants.

For more information, click here.

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