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Plant Profile: Poison Ivy, More Than A Scary Nuisance

poison ivy leaves
Photo by Karen Holmes.

When people think of poison ivy, itchy rashes are often the first thing to come to mind. However, there are some positives to this native plant!

Poison ivy contains the oil urushiol, which can irritate the skin and cause those itchy rashes. But it may surprise people to learn that it typically only affects two animal species:  humans and pigs. (Dogs and cats are not usually affected, but short-haired pets can sometimes have a reaction to poison ivy.) Other species in the Forest Preserves, including birds, insects and other animals, are not affected by the urushiol. In fact, the berries produced by poison ivy, which develop in fall, provide an important food source for many bird species during winter when other food sources are scarce.

In addition to serving as a food source for various animal species, poison ivy also provides a beautiful sight during autumn. Early in the season, the leaves transition to an array of stunning, warm colors including golden yellow and vibrant red.

How to Identify Poison Ivy

With the old adage in mind, “leaflets three, let it be,” learning how to spot this native plant is an important way to ensure comfort when exploring forested areas.

Poison ivy plants have compound leaves divided into three leaflets, while the vines of poison ivy are dark gray or black with ample hairs, by which the plant attaches itself to trees and other upright objects. The fruits are clusters of pale gray or whitish, pea-sized berries.

According to Alex Palmer, a naturalist at the Forest Preserves’ Sand Ridge Nature Center, Poison Ivy can often be confused with several other plant species found throughout the Forest Preserves.

“The leaflets and vines of the Virginia creeper look very similar to poison ivy, but Virginia creeper has five leaflets and is generally not toxic to touch, except that some people may contract a “photo-dermatitis” from contact with the fall foliage followed by exposure to sunlight. Black raspberries and blackberries, like poison ivy, often show leaflets of three, but those plants are covered with thorns, which poison ivy lacks,” explains Palmer. “Grape vines usually have hairs that are generally not as dense as poison ivy, and their fruits are dark purple when ripe. Also, grape leaves are simple whereas poison ivy has divided, or compound, leaves.”

Although these similar-looking plants will not cause a severe reaction the way poison ivy might, it’s best to avoid contact if visitors are not sure of the exact plant identification. Be aware that poison ivy is a sunny woodland edge plant and is commonly found along hiking trails. In addition to learning how to identify poison ivy, wearing long-sleeve shirts and pants to help cover skin is a great way to prevent skin irritation from possible contact.