How Do You Know If That Plant Is Poison Oak?

Are These Poison Oak Leaves or Not?

Poison oak growing on street corner in Pacific Grove, California
Poison oak growing on street corner in Pacific Grove, California. Wendy Bumgardner ©

Is that plant poison oak or not? Poison oak is a great imitator. Its leaves take on the shape of those of other plants nearby. After a couple of bouts of poison oak, you will have an incentive to become an expert at spotting it along the trail, road, and in your own backyard.

Is It Poison Oak? Leaves of Three, Let it Be

The one thing that doesn't vary for poison oak is the pattern of three leaflets branching from a single, independent stem. Two leaves are attached directly to the stalk opposite each other. The third leaf juts out from them at a right angle, so the 3-leaf pattern forms a triangle. There are no additional leaves on the same stalk.

The leaves may be serrated, round, or oak-like depending on what other foliage is around the poison oak plants. They may be shiny, or not. They may have a red tinge, or not. Be wary, or you're in for a week of itchy torture.

The plant itself may be seen as single stalks close to the ground with three leaves. Or a bush. Or a vine climbing a tree. Most of ​the photos here were taken on one trail, with the plants growing in a variety of ways.

Even if you live in an area where poison oak grows everywhere, you may not know which plants are poison oak is and which are not.

This photo is an example of poison oak growing profusely, almost as a hedge. You might think it was just another shrub as you passed by it at the street corner. This poison oak has rounded leaves rather than oak-shaped leaves, so you might not immediately think it is poison oak. But if you see that it has three leaves (and only three leaves) on each stem, that is your signal that it is poison oak

Oak-Shaped Leaves on Poison Oak

Oak-Shaped Leaves on Poison Oak
Oak-Shaped Leaves on Poison Oak. Wendy Bumgardner ©

This poison oak plant shows oak-shaped leaves. You can tell it apart from oak in that they are in the characteristic leaves-of-three pattern for poison oak. Don't touch it.

Round Leaves on Poison Oak

Poison Oak with Rounded Leaves
Poison Oak with Rounded Leaves. Wendy Bumgardner ©

The round-shaped leaves on this poison oak plant imitate those of the nearby trees. But note that it has the distinctive leaves-of-three pattern. Leave it alone.

Shiny Poison Oak Leaves

Poison Oak - Leaves of Three
Poison Oak - Leaves of Three. Wendy Bumgardner ©

Poison oak may look oily and shiny. It is the toxic oil that can give you the rash when it contacts your skin. But the leaves don't have to look shiny. They can still give you a dose of oil if they have a dull appearance.

If you come into contact with the leaves, wash the area as soon as possible with cool running water and soap. It's fine to rinse in a stream if you are in the woods. The good news is that poison oak isn't contagious, except when spread by the oil remaining on your garments, gear, or skin.

Poison Oak in Bloom

Poison Oak in Bloom
Poison Oak in Bloom. Wendy Bumgardner ©

Poison oak blooms are small white flowers, which may develop into greenish or tan berries.

Red Poison Oak Leaves in Autumn

Red Poison Oak in Autumn
Red Poison Oak in Autumn. Wendy Bumgardner ©

Poison oak leaves may turn a brilliant red in autumn as the bush dies back. Do not collect these leaves for decorations!

Poison Oak Is an Imitator

Poison Oak Imitates Nearby Leaves
Poison Oak Imitates Nearby Leaves. Wendy Bumgardner ©

Here the poison oak leaves are taking on the round shape of the bush next to it.

Poison Oak and Blackberry Vines

Poison Oak with Blackberry Vine
Poison Oak with Blackberry Vine. Wendy Bumgardner ©

Blackberry vines may appear to have only three leaves but usually have five. They also develop thorns.

Poison oak will only have three leaves on a stem, and the stem will not have any thorns. If it is growing next to blackberries, the shape of the leaves will imitate blackberry.

Poison oak is on the left and blackberry is on the right. Look closely at the stem for thorns on the blackberry vines.

Not Poison Oak—Maple Leaves

Maple Leaves - Not Poison Oak
Maple Leaves - Not Poison Oak. Wendy Bumgardner ©

These are maple leaves. They are not poison oak. The large leaves have three major lobes and two minor ones.

Oak—Not Poison Oak

Oak - Not Poison Oak
Oak - Not Poison Oak. Wendy Bumgardner ©

These oak-like leaves are probably oak, and definitely not poison oak. They are in a whorl of five leaves rather than a triangle of three leaves.

Round Leaves That Are Not Poison Oak

Vine with Round Leaves
Vine with Round Leaves - Not Poison Oak. Wendy Bumgardner ©

This bush has round leaves that are not in groups of three. It's not poison oak, but any poison oak next to it will imitate the round leaves.

Poison Oak or Not?

Poison Oak or Blackberry?
Poison Oak or Blackberry?. Wendy Bumgardner ©

Blackberry or poison oak? The three-leaf pattern is like poison oak. If there are any thorns on the stem, it is more likely to be blackberry. Better safe than sorry—leave it be!

Shiny or Red Oregon Grape Is Not Poison Oak

Red Oregon Grape - Not Poison Oak
Red Oregon Grape - Not Poison Oak. Wendy Bumgardner ©

This is the state flower of Oregon, Oregon grape, Mahonia aquifolium. It's shiny, but the leaf pattern is all wrong for it to be poison oak. It has more than three leaves per stalk. Some people identify poison oak by its red color in autumn. But here, Oregon grape is imitating red poison oak.

Poison Oak Close-up

Poison Oak
Poison Oak. Ed Reschke/Creative RF/Getty Images

This classic poison oak can make you itchy just looking at it. But looking won't give you a rash, you'd have to touch it or be exposed to the smoke if it burns, which can transmit the toxic oil.

To avoid getting a poison oak rash, the first step is not coming into contact with the leaves. Wear long sleeves and long pants and wear impermeable gloves if you are going to be working around poison oak or hiking in an area with poison oak.

Wash as soon as possible with cool water and a degreasing soap (such as dishwashing soap) if you have had possible contact with poison oak. Be sure to wash under your fingernails. You may also rinse with rubbing alcohol or a specialized poison plant wash. You need to thoroughly clean your clothing and gear. You may need to wash your dog or cat if he has tromped through the poison oak. You can use pet shampoo and cool water. Be sure to wear rubber gloves.

If you manage to get a rash, learn how to treat it


NIOSH Fast Facts: Protecting Yourself From Poisonous Plants. CDC.

Outsmarting Poison Ivy and Other Poisonous Plants. FDA.

The Poison Plants: Poison Ivy, Poison Oak & Poison Sumac. Cleveland Clinic.