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Giant Hogweed spreading across Canada

Wednesday, July 17, 2013, 2:12 PM -

Have you ever heard of Giant Hogweed? A few years ago, a few friends and I became very familiar with the name. Two events gave us the privilege of learning about the dangerous plant— the first was getting lost in a forest, the second involved a rafting trip. 

But first I should start by explaining what hogweed is. Giant Hogweed (Heracleum mantegazzianum) is a perennial plant, belonging to the carrot family. This plant can grow to be over 5 meters tall and flowers between the months of June and October.

Giant Hogweed

Giant Hogweed

The reason I called the plant ‘dangerous’ is because of the damage it can do when in it comes in contact with your skin. The clear watery sap in the plant contains toxins that can cause severe dermatitis. When it is exposed to sunlight, it can result in severe burns, if not blistering. The severity of the reaction varies from person to person and also depends on the amount of sap one has come in contact with. Swelling and reddening of the skin are noticeable after 24 hours but the symptoms can worsen and last for months. If the sap gets into your eyes it can cause temporary or permanent blindness. The burns can also cause scarring to the skin. 

Giant Hogweed is a very resilient plant which has the ability to shade out native plants. This has enabled it to grow and spread rapidly to different parts of the country. 

But the plant is not native to Canada. In fact, it originated from southwest Asia and Europe. And while it has been in Canada since the 1940s, it hadn’t begun invading different areas until recently. So when my friends and I decided to go on a rafting trip, we had never heard of or seen the plant before. It wasn’t until we ran into an older fellow that we learned of the plant. After politely smiling, the man began to initiate a conversation and warned us about the hogweed that we might encounter along our adventure. He seemed to have known the area quite well and described what it looked like and what exactly it could do if the sap got onto us. From that point on, we were on the lookout for hogweed.

Queen Anne's Lace

Queen Anne's Lace

It wasn’t long until we noticed a huge number of these plants that covered the area around the stream. The hogweed had thick hollow stems and large lobed leaves that bloomed white flowers. Its flowers resembled Queen Anne’s Lace, a common plant found in open areas. It is also commonly mistaken for cow parsnip. 

At this point it hit me. I recalled the last time we had been in this forest (and somehow got lost). During that time, I unknowingly must have come into contact with the sap. I found myself with a slash across my leg that resembled a burn. And sure enough, my skin began to blister slightly the following day. Thankfully for me the effects were not severe. It stung for the first couple days and the blister later subsided, leaving a scar which lasted a few months. 

And although my friends and I found the giant hogweed while venturing in a forest, it can now be found in public parks, gardens, alongside ditches, roads and streams, and in meadows and the woods. If you find hogweed on your property, it is highly recommended that you hire a professional to remove it because if the plant is not removed properly, it can continue to spread. You also run the risk of getting it on your skin. If this does happen, be sure to get the sap off as quickly as possible. 

For those looking for an easy way to identify if a plant is in fact hogweed, a smartphone app is being developed to track the species. This app should be available by mid-September. 

As for me and my friends, we have now become very familiar with the plant just in case we happen to cross paths with it again. And a word of the wise, when going on a hike or for a walk through a wooded area, be sure to take the paths and stay away from any plants that you do not recognize.

Stay away from giant hogweed, an invasive and dangerous plant
Adventures in gardening: garden design
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