How to Spot Muskoka's Invasive Terrestrial Plants

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How to Spot Muskoka's Invasive Terrestrial Plants

With the official start of summer only a couple of weeks away its time to talk about plants in Muskoka. More precisely invasive terrestrial plant species that threaten the biodiversity and beauty of our natural habitats. So, what is an invasive plant? An invasive plant is one that is not native to the local area. They are usually referred to as non-native or non-indigenous and have traditionally been spread as ornamental plant species or by accident. These species tend to spread and adapt much quicker than native species allowing for them to out compete the surrounding plants.
So, are there invasive terrestrial plant species in Muskoka?

Some would find it hard to believe but there are actually three such documented plants in the region! Their names are the European Common Reed (Invasive Phragmites Australis), the Japanese Knotweed (Fallopia Japonica) and the Giant Hogweed (Heracleaum Mantegazzianum). All three are faster at adapting and reproducing than our local plants. This meaning that it is only a matter of time before the native plants are unable to compete for nutrients or sun light and ultimately disappear.

So, let’s learn a little bit more about these three plants. The first thing to know about the European Common Reed is that it has 4 species and is found all around the world. In fact, there is a local subspecies of the reed that originates in North America but is much different than the invading plant. This invasive reed however, is characterized by its ability to grow extremely densely with as many as 200 stems per square meter. It is this extraordinary density and ability to grow up to 5 meters in height (15 feet) that causes it to crowd out other species. It can be distinguished from the native plant due to its stems that are tan or beige in colour and that have large extremely dense seed heads with blue leaves. In contrast the native plant which has more reddish or brown stems with much smaller less dense seed heads and yellow or green leaves. Some problems that this plant has caused beside competition with native plants is that it has been known to cause agricultural drainage ditches to become blocked resulting in flooding.  As well the stalks of this reed are very resistant to decay which can cause ponds to become full of them, causing dead zones which are unable to sustain wildlife. Below are some tools for extended knowledge or sighting advice.                                 

 Online Resources for European Common Reed Knowledge 

The Japanese Knotweed is a large perennial plant that is native to East Asia, China, Japan, and Korea. Also, by the latest scientific data it has said to have spread to every province besides Saskatchewan and Manitoba. The identifying characteristics of this plant are stalks that grow straight up and can reach as high as 3 meters. The stem is round with a purple and red colour with large lobed or heart shaped leaves and cream coloured flowers that grow vertically in clusters. It has an extremely strong root system that has been known to be able to spread up 10 meters even across road systems. This pest has also been known to disrupt river flows and spawning beds. It has been witnessed growing through roads and the foundations of houses as it is commonly alongside roads, in gardens, and near old buildings. It is believed to be extremely hearty and adaptable with stems being witnessed surviving at temperatures of -35 C. There are also studies that attribute the spread of the plant to climate change. More knowledge is available below.

Online Resources for the Japanese Knotweed

  • If you find invasive Japanese Knotweed or other invasive species in the wild, please contact the Invading Species Hotline at 1-800-563-7711, or report a sighting online.

The final and possibly most interesting and toxic of all the plants is the Giant Hogweed. It is native to the Caucus region of Central Asia. It is a giant plant that can grow from 2.5 to 4 meters which is one of the reasons for its threat to bio diversity in Muskoka. It is identified by its hollow stems with dark reddish-purple splotches and very coarse white hair. The serrated leaves are very deeply convex and can grow to a meter in size. It does produce flowers and they form an umbrella shaped head that can grow to over 30 cm in diameter. It is further identifiable by seeds that are oval shaped and flat. It is most commonly found at roadsides, stream banks and, vacant lots.

This plant also has a trick up its sleeve that makes its dangerous to humans. The Giant Hogweed produces a toxic sap that is known as phototoxic. It contains chemicals called furanocumarins these in turn can be absorbed by the skin and cause a condition called phytophotodermatitis. This exhibits itself on the skin with extreme UV light sensitivity often resulting in the appearance of blisters and scars that could become permanent if not treated. If contact is made with eyes it can also cause blindness both partial and permanent. Heat and moisture increase the effects of this sap. Many of our local plants look like the Giant Hogweed and due to its toxicity, it is not recommended to be handled by anyone but a specialist. Some of the similar plants include the Cow Parsnip, The Spotted Water Hemlock, The Poison Hemlock and Wild Parsnip.

Online Resources for the Giant Hogweed

  • If you find invasive Giant Hogweed or other invasive species in the wild, please contact the Invading Species Hotline at 1-800-563-7711, or report a sighting online

So how do you handle any of these specific plants if you have spotted them on your private property? First off, knowledge of how to identify these specific plants is key. If you find any on your property it is imperative that you dispose of them correctly. The European Common Reed is one plant that needs not to be planted no matter its visual appeal.  If these plants are found and removed, they cannot be composted as they have been known to flourish in composters. If you remove some of these plants from your property, they need to be placed in a sealed kitchen garbage bag. Then it needs to be taken to the Rosewarne Landfill in Bracebridge ( Here it is requested that you inform the staff that you are carrying an invasive plant species and from there it will be disposed of properly.

Managing the Japanese Knotweed is much more difficult as it is an extremely resilient plant that can survive getting dug out of the ground as well as being cut down and burnt. The key to eradicating this species is a series of cuttings throughout the year to try and deplete the root system underground. However, this could continue to make the problem worse, if the plants root system is not eradicated, it could return creating even more growing ends. Again, if this plant is found on your property it is not to be disposed of in regular lawn clippings or composted. This plant needs to again be placed in a sealed garbage bag and delivered to a landfill. However, this time it is the Briers Road Landfill in Gravenhurst. Again, it is requested that you inform the staff at the landfill of what you have so that it will be sorted appropriately.

Our final plant, the Giant Hogweed, has a different procedure all together. If it is found on your property it is recommended that you not touch the plant at all. Due to its toxicity and ability to injure it is recommended that you find a professional in your area to remove the plant. Just like the other two before it, it is not recommended to compost as it has the ability to continue to spread even while in the composter. Finally, after it is professionally removed follow up and monitor the area to make sure it doesn’t return.

All in all, Muskoka is a very diverse and beautiful eco system and we should take all the necessary steps to try and eradicate these invasive species for the benefit of our wildlife. It is highly recommended that if you spot any of these species you call the invasive species hotline (1-800-563-7711). LET’S KEEP MUSKOKA BEAUTIFUL!

Your friends at HRC Insurance.


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