Ontario Poison Plants

Before geocaching I had heard of poison ivy, who hadn’t, but I’d never heard of giant hogweed or wild parsnip.  Lucky for me I never had to worry about these plants before I learned about them.   Contact with any of the three plants I just mentioned can ruin a perfectly good day of geocaching.

I don’t have too much trouble identifying giant hogweed, it really is giant!  Identifying wild parsnip is also a fairly straight forward process, I just look for the yellow flowering section.  Poison ivy on the other hand gives me fits!   The only time I’ve ever received a rash from poison ivy was the  one time I knew I was walking through it but I wanted to get to that geocahe and it was surrounded by this irritating plant.   Maybe the cache should have had a nigher difficulty rating because of the plant!

Something to keep in mind when dealing with these plants is that they can be irritating even out of season.  Poison ivy can be irritating even in the winter.   It is the naturally produced oils of poison ivy that can lead to a rash.  These oils are present on the outside of the plant including the leaves and other parts of the plant.  Handling of wild parsnip can have similar effects as poison ivy and in fact the symptoms are often incorrectly attributed to poison ivy.   The sap of the giant hogwood contains the compounds that are hazardous to humans.  Contact with all three plants should be avoided at all times.

We have compiled a gallery of images that will help you identify these plants.   Take note of the details in the black and white line drawings.   It is best to learn the distinguishing characteristics as well as what it looks like.  The plant will look different based on the time of year and the lighting conditions present.

The ministry of Agriculture has compiled and excellent resource on weeds.   Here are links to the pages for these plants on that site:

You aren’t likely to stop geocaching because of these plants so what can you do to hep prevent any problems from contact with Ontario’s poisonous plants?

  1. An ounce of prevention is worth a pound of cure.  Learn how to identify these plants.
  2. Wear protective clothing if you know you will be in contact with any of these plants. Be careful removing your protective clothing.   Oils and sap will remain on items that have come in contact with these plants.
  3. Use a commercial treatment ( links provided for convenience, these products have not been tested or endorsed by the OGA)
  4. As with insect repellant there is a product that claims to protect you from getting a rash should you come in contact with poison ivy.  Ivy Block is applied before contact.


About teamvoyagr

I am the webmaster for the Ontario Geocaching Association. I've been passionate about geocaching since 2006. You can find my articles about Geocaching on this site as well as on my blog for geocaching stories.
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3 Responses to Ontario Poison Plants

  1. Sarah says:

    Something I learned through experience is that if you come into contact with poison ivy that the reaction can be averted by washing with soap and COLD water within 15 minutes. We learned that the cold water is important to close your pores to keep the oils out. Luckily lake water is cold :) We used this method and averted reactions in two adults and 5 kids. SO glad it worked!

  2. waterloo.bob says:

    This is a timely post. I don’t think I’ve ever seen such a proliferation of Giant Hogweed as I have this season. It seems to be everywhere. I was also aware of Wild Parsnip. These two are easy to identify but Poison Ivy gives me fits. ‘Leaves of Three’ seems to be the identifying mantra. Any idea how much vegetation has leaves of three? It seems like they all do. From the photos above the poison ivy leaves seem quite large. Then again there is nothing to judge them against. Are they large? Are there any other identifying characteristics? And does anyone know if there is a certain point in the development of Giant Hogweed and Wild Parsnip when they become noxious? I’m wondering if they still are a problem when they’re growing and haven’t reached the Giant stage. If that’s the case I’m looking at Queen Anne’s Lace with a whole lot more respect as it and Giant Hogweed seem to look identical in early stages. Thanks for the post.

  3. Sandi says:

    Thank you for the reminder that there is more than just poison ivy to look out for. I’m just curious… was this article supposed to continue after “Another….” ? (end of article).

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