Differences Between Poison Oak & Poison Ivy

The plants that cause poison ivy and poison oak both contain an oil known as urushiol, which can cause an allergic reaction when it comes in contact with skin. You can get this reaction from direct, indirect, or airborne contact with the oil, so it is important to learn how to identify and avoid poison ivy and poison oak. The main difference between these plants is in their appearance.

Growth

• Poison ivy grows as a low shrub or as a vine (often using a tree for support). Poison oak is a shrub.

Flowers

• Poison ivy and oak plants grow flowers in the spring, and the plants themselves can turn a reddish color in the fall. Poison ivy also sometimes grow a berry-like fruit in the fall.

Leaves of Three

• Both poison ivy and poison oak have clusters of three leaves on each stem, and the middle leaf is longer than the other two. The poison ivy leaves have three main points each, while the poison oak leaves have slightly more serrated edges.

Developing a Rash

• Although usually takes more than one exposure to urushiol for a person to experience and allegic reaction, sensitivity to the oil usually decreases with age.

History

• According to the Poison Ivy, Oak, and Sumac Information Center website, Captain John Smith coined the term "poison ivy" in 1609, while David Douglas discovered poison oak (the Douglas Fir is also named for him).