Grow Your Invasive Species Knowledge

Grow Your Invasive Species Knowledge

We can’t see them now but lurking beneath the snow are invasive plants. Next week is Invasive Species Awareness Week. It’s the perfect time to learn more about these pesky plants so you can avoid planting them in your garden come spring.

Invasive species are non-native plant, animal or pest species that outcompete native species for resources and dominate space. They provide less habitat for our native wildlife and have ecological and economic impacts.

You may have heard about dog-strangling vine or garlic mustard but invasive flowers, grasses and shrubs are often unknowingly planted in gardens.

Here are four lesser-known invasive plants with beautiful native plant alternatives:

Winged euonymus (Euonymus alatus)

Winged euonymus, also called burning bush, is a shrub native to Northern Asia. First introduced to North America in the 1860s, it has since spread into southern Ontario. Often planted in hedges and plant beds, it’s also found along highways and in natural areas throughout the Credit River Watershed.

Winged euonymus can grow in a variety of soil and light conditions. As a fast-growing plant, it can grow two and half meters high. The dark green, tear-shaped leaves turn bright red in fall.

Downy serviceberry is a great native alternative.

Oriental bittersweet (Celastrus orbiculatus)

Oriental bittersweet is a vine native to China, Korea and Japan. As a shade-tolerant plant, it grows in forests and woodland edges but can also grow in full sun in grasslands and along roadsides. There are isolated patches of oriental bittersweet throughout the Credit River Watershed.

Oriental bittersweet grows by wrapping around shrubs and trees. Its glossy leaves are rounded with finely toothed edges. This aggressive plant quickly takes over and can even kill large trees.

Attractive greenish yellow flowers bloom from May to June and create orange berries in fall. Birds help spread their seeds when they eat the fruit.

Virgins bower is a great native alternative.

Japanese silver grass (Miscanthus sinensis)

Japanese silver grass, also called Chinese silver grass, was brought to North America as an ornamental grass. Like many ornamental plants introduced from overseas, it has moved into natural areas.

It grows one to two metres tall in dense clumps with long, thin arching stems that give it a fountain-like appearance. Flower heads look feathery and bloom from August to October.

Japanese silver grass grows quickly in a variety of soil types, from sand to heavy clay, allowing it to outcompete native species for nutrients and water. Try native grass alternatives like switchgrass and big-blue-stem in your garden.

Wild chervil (Anthriscus sylvestris)

Wild chervil is a popular plant found in European wildflower mixes that have made their way to North America.

Wild chervil is in the parsley family. It grows 30 centimetres to 1.2 metres tall, but on occasion can grow almost two metres tall. Small white florets bloom at the top of the stem. The seeds are green and turn a shiny dark brown as they mature.

Black-eyed Susan is a great native alternative.

You can find alternatives to invasive plants to add colour, beauty and interests to you garden in our Guide to Gardening Wisely. Enjoy the many benefits of native plants in your garden from creating habitat for beneficial insects like bees and butterflies and other wildlife that depend on them.

Between February 22 to 26, follow us on Facebook and Twitter to learn more about how you can help stop the spread of invasive species during #InvSpWk .

Managing the Impacts of Invasive Species
We are continuing our work on the Emerald Ash Borer Restoration Project at Rattray Marsh Conservation Area. Ash trees have been devastated by emerald ash borer (EAB), an invasive insect. From February 22 to March 13, restoration staff will be removing dead standing ash trees in priority sections of the forest.

By Kimberley Laird, Associate, Marketing and Communications

5 Comment
  • Maple says:

    All Earth bound spieces are invasive. Humans beings probably being the most invasive of all.

  • Allen Cooper says:


    • Thanks for posting your observation. Yes, this Emerald Ash Borer infestation is like nothing we have ever seen before. What you are noticing in your trees is called ‘blonding’ and it’s caused by woodpeckers pecking away the tree’s rough outer bark trying to feed on the many EAB larvae underneath the surface. This leaves the smoother, lighter-coloured inner bark exposed and is causing the effect you are seeing. What it means, unfortunately, is that your trees are now quite heavily infested with ash borer larvae and if they aren’t dead already your ash will probably not survive for much longer. It’s a sad story that we have seen over and over again in our watershed. If you have any further questions or observations, please email and we will get you in touch with an expert to discuss further. Thanks!

  • Edythe stiles says:

    I have noticed over the past few years that something seems to be attacking our maple trees. I’m not sure exactly what . It may even be our weather conditions. We have lost 😞 three over the past few years? Some of the branches seem to die and you notices few brown leaves and gradually within 2 or three years they are dead. We did notice these flying insects coming from the bark. They resembled dragon flys but on a smaller scale.
    Any ideas?

    • Hi there! We’re sorry to hear that you are losing some of your Maple tree’s. Unfortunately, it is difficult to diagnose the problem as it could be a number of things, some of which you have mentioned. It could be caused by stress from changing localized conditions such as weather, water levels, and soil conditions. There are a number of fungal or bacterial diseases which can attack some Maple’s. As well as the chance an insect pests could be contributing to the decline. We would be happy to discuss in more detail to see if we can narrow down the cause. Please feel free to contact and we will get you in touch with an expert. Thank you!

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