One of Canada's most dangerous plants is about to start blooming in Toronto

Invasive plants are no joke, and one of the country's most dangerous will soon be blooming again, right here in Toronto.

Giant hogweed may look pretty and lacey with delicate white blooms, but touching the plant and its sap can cause photodermatitis (skin sensitivity to sunlight), rashes, blisters and even blackening of the skin.

The effects of the plant can last months or in the case of photodermatitis, even years. If the sap comes into contact with the eyes there's a possibility of permanent blindness.

The umbrella-shaped head of giant hogweed can reach 20 inches in diameter. Photo by Bill Kasman.

Of course, giant hogweed can also be hazardous to pets. If you suspect your pet has come into contact with it, be careful not to touch them with bare hands but use protective gloves to wash them with soap and water and get them to the vet immediately.

The plant can reach 20 feet tall, has reddish-purple blotches and bristles on its stalk, a large umbrella-shaped head and large leaves that can reach five feet wide. It's usually found along stream edges, forest edges and road sides.

It looks a lot like Queen Anne's Lace/Wild Carrot, Cow Parsnip and Angelica, but there are certain differentials in appearance that can help you tell them apart, like height and the look of their flowers, stalks and leaves.

Giant hogweed can look very similar to other plants but has identifying traits. Photo by Joost J. Bakker IJmuiden.

You can report sightings of giant hogweed in Toronto parks to 311, but be careful to consider these factors.

If you report giant hogweed and qualified staff find it to be present in a location, they'll map where it is and put caution signs in areas where it presents a risk to the public, sometimes even fencing areas off. Sometimes even properly applied pesticides are used.

Along with being able to identify the plant and stay away from areas where it's been spotted, of course the best way to avoid coming into contact with it is to stay on marked trails, and for pets, to keep them on leashes.

Giant hogweed starts growing in Ontario in late spring around mid-May, so now is the time to start keeping your eyes peeled.