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| hogweed A stand of giant hogweed near Waterloo. The noxious and prolific weed has been found in Guelph. |
City staff recently confirmed the noxious plant was found in the front yard of a residence on Dufferin Street in downtown Guelph.
Jessica McEachern, a biologist by training who has conducted plant identification in the past, inspected the weed with Randy Drury, Guelph’s civic weed inspector.
“Both of us, when we saw the plant, knew what we were looking at,” said McEachern, a City of Guelph environmental planner.
François Tardif, an expert in weed science at the University of Guelph, has confirmed two cases within the city limits: the plant at the Dufferin Street address and another stand in nearby Highview Park, where it overflows into a private backyard.
But others are not so certain the Dufferin Street plant is bona fide hogweed.
The resident at the home in question, reportedly an ecologist who has mapped and inventoried hogweed in the past, insists the plant is cow parsnip, and refuses to remove it, McEachern said.
“I believe there was a difference of opinion about what was being observed,” McEachern said. “I don’t think there was any intention of removing it.”
Nigel Finney, a natural heritage ecologist with Conservation Halton who also saw the Dufferin Street plant, said he is “almost certain” it is hogweed.
But whether it’s hogweed or cow parsnip, “they both cause photosensitivity in some people and should be removed,” he said.
Even Tardif said he was only 95 per cent sure. “I may be wrong. Scientists are never 100 per cent sure,” he wrote in an email.
McEachern said she recognized the plant by its height and the purple pubescents on its stalk.
“I mean, no one’s broken the plant to see if it causes photodermititis,” she said. “All I can really say is that both myself and Randy felt very confident with what we were looking at.”
While the city is responsible for destroying hazardous plants found on public property, homeowners have historically been expected to handle plants in their private backyards and gardens.
As public awareness and fear of the plant grows, many residents have mistaken similar plants in the parsley family, such as cow parsnip and wild carrot, for giant hogweed.
Heracleum mantegazzianum, better known as giant hogweed, was carried from Asia to Canada in the mid-1900s and has been spreading throughout southern Ontario in the past decade.
It contains a phototoxic sap that can burn skin, permanently damage the eye or, in extremely rare cases, lead to asphyxiation. A prolific breeder, a single hogweed flower produces thousands of seeds that travel by wind, water or wildlife to adjacent lands.
Asked if the plant is likely to burgeon in Guelph, McEachern said, “It seems to be the general trend in all other locations where it’s been identified. So without proper disposal, I suppose it is a risk.”
The proximity of Dufferin Street to local waterways might be cause for extra concern, Finney said, since the plant could put the floodplain area around the Eramosa and Speed Rivers at risk.
McEachern said the city is “starting to get the ball rolling” on a public education campaign about the weed. “We’re definitely starting to do that now, as we speak,” she said.
Attempts to reach the owner of the house on Dufferin Street were unsuccessful.
