You may know the saying "leaves of three let it be" or some other passed down description of poison plants, but poison ivy, oak and sumac can be hard to identify. All three plants contain the same allergen causing the same reaction to your skin so your doctor may call out any of the plants when identifying your rash.  Learning what the plants look like and where they grow can help identify if it is poison ivy, oak or sumac.

Poison ivy with berries

Where does poison ivy grow?

The most widespread of the three, poison ivy is found throughout most of North America, including all of the United States with the exception of California, Alaska, and Hawaii. Poison ivy can grow in many forms including a groundcover, shrub or a climbing vine. Poison ivy prefers "disturbed ground" so you can find it growing along the edge of your backyard, along paths, up trees and fences, and mixed in with your landscaping.

The best way to identify poison ivy is by its almond shaped leaflets of three - each stem ends with three leaves. The color of the leaves can change from green to red with the seasons, and it can contain berries of a grayish-white color (but not always).

Poison ivy map

Where does poison oak grow?

Red and green poison oak

Poison oak is not as widespread as poison ivy, but to make things more interesting there are two species found in the United States, Eastern Poison Oak and Western Poison Oak. Don't let the terms confuse you though, the plants look the same. Poison oak has three leaflets like poison ivy, but they are scalloped and shaped like the leaves from an oak tree.

Like poison ivy, poison oak likes "disturbed ground" but is also commonly found in oak woodlands and Douglas fir forests. Poison oak can grow as a shrub in the sunlight or a climbing vine in areas that are shaded with colors ranging from bronze, bright green, yellow-green or red as the seasons change. Poison oak may also contain greenish-white or tan berries.



Pacific poison oak map

Atlantic poison oak map


Poison sumac red stemsWhere does poison sumac grow?

Unless you live in the swamp, it is very unlikely you will ever cross poison sumac in your yard. Found in the Eastern United States, poison sumac grows as a wooded shrub that may look like a small tree (grows up to 20 ft.) located in very wet areas like swamps and peat bogs.

The number of leaflets found on poison sumac are always an odd number, typically ranging from 5-13 leaflets per stem, with a single leaf at the end of the stem. Poison sumac stems are red in the spring and become brown as the seasons change. Poison sumac also produces clusters of small berries that are not perfectly round (more oval in shape) and white or grey in color.

Poison sumac map

What is causing my rash in Hawaii?

Although poison ivy, oak and sumac do not exist in Hawaii, the skin of the mango tree produces the same rash causing allergen, urushiol. Just like with poison ivy, oak or sumac, you want to remove this rash-causing oil from your skin if you have been in contact with it.