Report giant hogweed, Nature Conservancy urges about toxic species

The Nature Conservancy of Canada is urging the public to document sightings of giant hogweed, the­ towering green plant with large umbels of white flowers and a toxic clear sap, as the weed spreads across Canada. 

It can cause third-degree burns and even permanent blindness. 

• 5 things to know about giant hogweed
• Why we can't stop the spread of giant hogweed
• ​Invasive hogweed spreads in B.C.
• Hogweed creeps across Nova Scotia​

Dan Kraus, a biologist with the conservancy, says the invasive species likely arrived in Canada in the 1940s as an ornamental plant and can now be found in the Atlantic provinces, Quebec, Ontario and B.C.

Its clear sap can cause blistering third-degree burns and even permanent blindness if it touches the body and is then exposed to the sun, through a phototoxic reaction.

Kraus says there is also a concern about a loss of native biodiversity, as giant hogweed is an aggressive plant that can
outcompete native plants and spread -- especially when it grows near rivers and streams and its seeds are carried downstream.

He says the conservancy is asking people to document sightings of the invasive plant through apps such as iNaturalist, which helps scientists understand how the plants are spreading and identifies areas they need to be eradicated.