09/14/2026
How to Identify Poison Ivy (Toxicodendron radicans)
In the Canyon, poison ivy is scattered throughout the area, so it is important to know how to identify it to avoid potentially developing a rash from contact with exposed skin.
Harmless plants that are often confused with poison ivy include Virginia creeper (Parthenocissus quinquefolia) and boxelder (Acer negundo).
Poison ivy is best identified by its clusters of three leaflets. Notice how the three leaflets grow together from a single point. The two side leaflets typically have little to no stalk, while the center leaflet has a noticeably longer stalk. This is one of the most reliable characteristics to look for.
The shape of poison ivy leaves can vary greatly, even on the same plant. However, there are a few common features to look for:
* The side leaflets may have one or more “thumbs” or lobes along their outer edges, while the center leaflet may have lobes on both sides.
* Some leaves may have no lobes at all.
* Leaf edges may be toothed or completely smooth.
* In the fall, poison ivy leaves can range in color from yellow to bright red.
Poison ivy can also grow in several different forms. It may appear as a low-growing ground vine, a climbing vine, a free-standing shrub, or occasionally even a small tree. However, the climbing vine form is the most common.
Remember: the entire plant can cause a reaction, not just the leaves. Poison ivy commonly grows in partly sunny areas, including forest edges, along walls and buildings, and near waterways.
"Leaves of three, let it be" and "Longer middle stem, beware of them"
Illustration by Dan McGregor