This week’s feature plant has quite the reputation for itself around town. If you know it, you sure don’t love it!
I’m quite the giant that over-towers,
With leaves so wide and firework flowers,
My sap burns the skin and erodes the soil,
To get rid of me, you’ll have to toil.
As one of Squamish’s Most Wanted weeds, Giant Hogweed (Heracleum mantegazzianum) has become quite the celebrity in the Sea to Sky region. For good reason, this monstrous invasive is known for its poisonous, photosensitive sap.
Hairs on Hogweed stems and leaves exude a clear, watery sap that sensitizes the skin to UV radiation (sunlight), resulting in severe burns, blistering, and painful dermatitis (skin irritation). Contact with the eyes can even cause temporary or permanent blindness. Use caution when walking by or working around Giant Hogweed as brushing against the plant, handling plant material, and even handling tools used on the plant can result in contact with the sap.
Despite these public health concerns, Giant Hogweed, native to the Caucasus Mountains in southwestern Asia, was introduced to North America as an ornamental for its showy flowers and enormous size. An individual plant can reach an impressive height of 2-5 meters. Proportional to its large height, Giant Hogweed’s maple-shaped leaves grow up to 3 meters long.
Giant Hogweed is distinguishable by its multiple large, umbrella-like clusters of small white flowers. These flowers closely resemble those of its native cousin, Cow Parsnip. However, Cow Parsnip is much smaller in leaves, flower clusters, and height. Be careful! Cow Parsnip also contains a toxic sap that causes severe burns when exposed to sunlight.
Giant Hogweed is a source of several ecological concerns. For one, it out-competes native plants due to its tolerance to full shade, vigorous early-season growth, and ability to coexist with other widespread and invasive plant species. Moreover, infestations can result in increased erosion hazards in riparian areas due to characteristically shallow roots.
Giant Hogweed is well established in Metro Vancouver and infestations have spread to Lions Bay, Squamish, and Pemberton. As large efforts have been put into controlling Giant Hogweed in the Sea to Sky region, SSISC aims to eradicate infestations and prevent it from spreading to Whistler. If you think you’ve spotted this monstrous invasive, report it here.
I Spy in the Sea to Sky Contest
Guess the invasive species in our I Spy in the Sea to Sky weekly social media post, June through August, to enter the giveaway. At the end of each month, one lucky commenter will win a Native Wildflower seed mix packet!
Contest Rules:
- Comment your guess (common/species name) on either Facebook or Instagram post to enter
- One entry per person per post
- Anyone can play, but only residents of the Sea to Sky region are eligible to win (as prizes will be delivered)
- Content entries will close at 11:59 PM PST on the last day of the month
- Winners will be announced in the first week of the following month on the SSISC Instagram story and contacted via their platform of entry
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