close up of bright green leaves


Poison-ivy is widespread throughout southern Ontario and is toxic to the skin. The offending substance of the plant is an oil which is present throughout root, stem, leaf, flower, and fruit. Poison-ivy grows in deep woods or in the open; in dry, sandy areas, crevices of rocks, or swamps; along the borders of woods, fencerows, or roadsides. Each leaf consists of three leaflets. Leaves may be red, green, or slightly yellow. 

Poison-ivy is classified as a noxious weed under the Ontario Weed Control Act. This legislation provides a means for regulating control of certain weeds in problem areas. Cooperation and united effort are essential to controlling poison-ivy, but responsibility falls to each person to recognize it, teach others to recognize it, and avoid contact with it.

Poison Sumac

Poison sumac is distinguished by its appearance as a coarse shrub or small tree, its alternately arranged, pinnately compound leaves with 7-13 usually smooth-margined leaflets and its clusters of white flowers followed by whitish berries. The entire plant is as poisonous to most people as Poison-ivy. Because both the foliage in summer and the bare twigs in winter can cause severe dermatitis, take special care to avoid these parts touching hands or face when in damp woods.

Dog-strangling Vine

The Dog-strangling Vine is a plant that forms thick strands that overcome and crowd out natural plants and trees. It prefers open, sunny areas but can be found in natural and disturbed areas. It is also found in shaded forests. In recent years, this lookalike member of the milkweed family has spread quickly throughout central and southern Ontario.

The plant produces thousands of seeds per square metre. The seeds can easily be spread by the wind. This perennial vine has invaded ravines, hillsides, fence lines, stream banks, and roadsides. Damaging results from dog-strangling vine are that it can destroy vegetation, agricultural fields, and block access into trails. If nothing is done to prevent the spread of the vine, it will suffocate trees by climbing up and wrapping itself around the leaves. The vine threatens the monarch butterfly. The butterflies lay their eggs on the plant, but the larvae are unable to complete their life cycle and do not survive.

Options to control the vine are chemicals, mechanical, cultural, biological, and combined weed management. A natural control for the vine is the Hypena Moth which is currently being tested in Ontario.