No one wants to come back from a hike covered in itchy, blistery skin simply because they brushed up against a poisonous plant. These plants here are common throughout North America and can be potently irritating year-round. Some basic awareness of what the plants look like goes a long way to steering clear.

The Big Three

Poison Oak, Poison Ivy, and Poison Sumac all produce an oily substance, Urushiol, that causes redness, irritation, and even blistering upon contact. Inhaling the smoke of burning Poison Ivy can cause lung irritation that is extremely dangerous.

Poison Oak

 “Leaves of three, Let it be.” Found in most of North America, Poison Oak appears as a vine or shrub with lobed or toothed oak-like leaves that grow in groups of three from a single stem. Leaves can be green and turn bright red in autumn. Touching the leaves of this poisonous plant will cause an itchy reaction and rash.

Poison Ivy

Found in all US States, Poison Ivy is especially common in woody areas, growing as ground cover, shrub, or vine. Poison Ivy is not a true ivy, and it’s bright, light green ivy-looking leaves grow in clusters of three leaves from a single source area with the center leaf sticking out a bit farther than the rest. The plant has a sturdy hairy stem. Touching the leaves causes redness, itching, and blistering of the skin. 

Poison Sumac

Found in the Eastern US and Canada, Poison Sumac grows in swamps, wetlands, and bogs. Growing from a shrub to small tree, the glossy green to red leaves cause redness, itching, and irritation when touched. The leaves turn bright red in autumn.

Also on the list: Stinging Nettle

Found throughout the US and Canada, Stinging Nettle is grows in areas of moisture: streams, forests, ditches, and woodlands. The delicate plant grows from the ground with lacy-edged leaves and has delicate flower-like tendrils at top. Contact with the plant causes itching, blisters, and burning as the nettles’ hairs sting you with their poison.