While both poison ivy and poison oak contain the same rash-inducing oily sap called urushiol and share some similarities, there are key differences in their appearance and growth habits that can help you tell them apart.
Here's how to distinguish between them:
Leaf Characteristics:
* Poison Ivy:
* Typically has three leaflets per leaf.
* Leaflet edges are often more pointed or jagged.
* Can have a "mitten-like" shape with a larger tooth or lobe near the bottom of some leaflets.
* Leaves can be shiny, especially when young.
* May have a reddish spot where the two bottom leaflets join.
* Poison Oak:
* Also has three leaflets per leaf.
* Leaflet edges tend to be more rounded or lobed, resembling oak leaves.
* The undersides of the leaves are often fuzzy and lighter in color than the top.
* Leaves may not be as shiny as poison ivy.
Growth Habit:
* Poison Ivy:
* Most commonly grows as a vine that can trail along the ground or climb trees, houses, or other vertical surfaces.
* Larger vines can appear "hairy" due to tiny roots extending from them.
* Can also grow as a shrub.
* Poison Oak:
* More often grows as a shrub, with leaves crowded near the tips of upright stems that can reach up to 3 feet tall.
* Can also grow as a vine, particularly in the Western U.S.
Location:
* Poison Ivy: Found in a wide variety of habitats across the lower 48 states, common in wooded areas, forest edges, and urban green spaces.
* Poison Oak: Typically found in drier areas like pine and scrub oak forests, and is more common in the western and eastern U.S.
Other Identifiers:
* Both plants produce clusters of small white to tan fruit. Poison oak fruit (called "drupes") is tan.
* The leaves of both plants change color with the seasons. Poison ivy leaves turn reddish in spring, green in summer, and yellow, orange, or red in fall. Poison oak leaves are green in spring and summer, becoming more yellow with brown undertones, or even vibrant red, in autumn.
The old adage "leaves of three, let it be" is a good general rule for both poison ivy and poison oak. It's also important to remember that all parts of these plants contain urushiol, the oil that causes the rash, and this oil can remain potent on surfaces for long periods.