Newfoundland is the only province in Canada where poison ivy is absent. Illustration by Mary Peterson
Poison ivy can be found in every province of Canada except Newfoundland. It can grow as a shrub, climbing vine, or ground cover, and the branches of older vines can even be mistaken for tree limbs. The character of growth varies according to location and type. Western poison ivy (Toxicodendron Rydbergii) usually grows as an erect shrub, while Eastern poison ivy (Toxicodendron radicans) grows as climbing or trailing vine. As the names suggest, Western poison ivy predominates in Western Canada, while Eastern Poison ivy predominates in Ontario, Quebec, and the Maritimes.