Poison oak has leaves that look like oak leaves, usually with three leaflets but sometimes up to seven leaflets per leaf group. It grows as a vine or a shrub. Poison oak is rare in Canada, but it can be found in remote areas on the east coast of Vancouver Island and some nearby islands.

Poison sumac has 7 to 13 leaflets per leaf stem. The leaves have smooth edges and pointed tips. Poison sumac grows as a shrub or small tree. It is found in wooded, swampy areas, such as southern Ontario and southern Quebec, and in wet, wooded areas in the northern United States.

Poison ivy usually has three broad, spoon-shaped leaves or leaflets ("Leaves of three? Let it be!"), but it can have more. It may grow as a climbing or low, spreading vine that sprawls through grass (more common in southeastern Canada) or as a shrub (more common throughout Canada, especially the Great Lakes region).