Cow Parsnip and Giant Hogweed

The average person can identify more corporate logos than they can local wild plants. It’s natural for people to fear the unknown, but this fear is sometimes taken to needless extremes. I often see this with two similar-looking PEI plants just beginning to flower now: the native and common Cow Parsnip (Heracleum maximum) and the invasive and uncommon Giant Hogweed (Heracleum mantegazzianum).

Giant Hogweed has been the subject of sensational headlines both across Canada and the throughout US. While it’s true this plant can harm the unwary, I guarantee it’s not going to leap out and attack you. It’s great that the public is aware of this plant, but sad that it has generated so much fear. Many are now suspicious of any tall plant: one recent local social media post about the innocuous, native (and edible!) Tall Blue Lettuce (Lactuca biennis) had comments warning that it could be Hogweed.

Photo 1: I'm sharing this goofy photo for a reason! To show that Cow Parsnip is nothing to be afraid of. While I would not rub its sap on my skin (I wouldn't do that with any member of the Carrot Family), causal contact isn't a problem unless you have a specific allergy.

Giant Hogweed and Cow Parsnip are part of the Carrot Family (Apiaceae), a group of plants that has many members containing natural chemicals called ‘furanocoumarins’. If you get these chemicals on your skin and then that skin gets exposed to sunlight, the result can be serious and long-lasting burns. The good news is these chemicals are in the sap, not on the surface of the plant. Unless you have an allergy, it is perfectly safe to touch these plants (as I am demonstrating with Cow Parsnip in Photo 1). I certainly wouldn’t cut either plant without wearing protective equipment (or put the sap of any member of the Carrot Family on my skin), but I’m not worried about casual contact. I’d be far more concerned about touching Poison Ivy (Toxicodendron radicans) or Wood Nettle (Laportea canadensis)!

Photo 2: Cow Parsnip stems have rows of purple and soft-looking hairs.

Cow Parsnip is common across PEI, including along many of our streams and trails; there’s a patch of it along the Confederation Trail in Hunter River that I get called about every year. Height alone is not a good way to tell our native species from the invasive one: mature Cow Parsnip can be taller than young Giant Hogweed. Leaves and flowers can also seem similar if you’re not used to plant identification, so I recommend looking at the stem. Cow Parsnip stems will either be all green or have purple spots regularly arranged into rows, along with soft-looking hairs (Photo 2). Giant Hogweed will have randomly scattered, raised purple blotches and stiff-looking hairs (Photo 3).

Photo 3: Giant Hogweed stems have scattered, raised purple blotches and stiff-looking hairs (image source: kingcounty.gov).

If you have a plant that you think could be Hogweed, you can send me photos for ID. If it IS Hogweed and you need assistance with removal, you can contact the PEI Invasive Species Council. The Council does great work and has a ton of wonderful educational resources. Head on over to their Facebook page and give them a Like or Follow, or check out their website.

Giant Hogweed is an invasive species that should be removed when found (because it outcompetes native vegetation, not because of its sap). Cow Parsnip is a natural part of PEI untamed that just needs a bit more recognition and understanding.