Toxic, invasive giant hogweed plant spreading in Ottawa, warns conservation group

An invasive species of plant can be found in Ottawa.

The Nature Conservancy of Canada (NCC) is warning people that giant hogweed, which is toxic, is flowering this summer.

The NCC calls it “one of Canada's most dangerous plants.” Its toxic sap can cause rashes and blistering. If it touches bare skin and is then exposed to the sun, it can cause a third-degree burn, warns the NCC. 

The non-native, towering green plant can grow up to five metres tall and contain up to 50,000 seeds. It has large clusters of white flowers and purple prickly stems.

Giant hogweed can often be found at the side of the road, along streams and in open fields. 

The invasive plant has been seen in B.C., Ontario, Quebec and the Maritimes.

The conservation group is urging people across the country to document sightings of the plant – and have it professionally removed.   

“A single plant can produce thousands of seeds per year and it can spread quickly,” said Andrew Holland with the NCC. “The seeds are dispersed when they fall into rivers and streams and can be dispersed short distances by the wind. 

“Because it's a tall perennial, giant hogweed can take over large areas along rivers and streams, outcompeting our native vegetation.”

Holland says giant hogweed was brought to Canada from Eastern Europe and Asia in the 1940s.