Topic Overview

Poison ivy, oak, and sumac are found throughout the continental United States. In general, poison ivy grows east of the Rocky Mountains, poison oak west of the Rocky Mountains, and poison sumac in the southeastern United States.

See a picture of poison ivy, oak, and sumac.

The plants may look different depending on the season and the area where they are growing. But all of these plants have small white, tan, cream, or yellow berries in the fall. Their berries can help distinguish them from harmless but similar plants.

After the leaves have fallen off, these plants can sometimes be identified by the black color on areas where the oil in the plant (urushiol) has been exposed to air.

Poison ivy

Poison ivy is found everywhere in the United States except Alaska and Hawaii. It is most common in the eastern and midwestern states. It is less common outside the United States, but still found on every continent.

Poison ivy:

• Usually has three broad, spoon-shaped leaves or leaflets, but it can have more. The phrase, "Leaves of three? Let it be." may help you remember what poison ivy looks like.
• Grows as a climbing vine or a low, spreading vine that sprawls through grass (more common in eastern states) or as a shrub (more common in northern states, Canada, and the Great Lakes region).
• Often grows along rivers, lake fronts, and ocean beaches.
• Has bright red leaves and white or cream berries in the autumn.

Poison oak

Poison oak is most common in the western United States, although it is also found in eastern states. It rarely is found in midwestern states.

Poison oak:

• Has leaves that look like oak leaves, usually three leaflets but sometimes up to seven on each leaf group.
• Grows as a vine or a shrub.

Poison sumac

Poison sumac is much less common than poison ivy or poison oak. It is found in wooded, swampy areas, such as Florida and parts of other southeastern states. It is also found in wet, wooded areas in the northern United States.

Poison sumac:

• Has 7 to 13 leaflets on each leaf stem. The leaves have smooth edges and pointed tips.
• Grows as a shrub or small tree.

Where they are not found

• None of these plants grow well above 4000 ft (1219 m), so the higher elevations in places such as the Rocky Mountains are relatively free of them.
• None of these plants grow well in deserts, except along the banks of rivers, streams, and ponds. But heavy rainfall can make a dormant plant grow again, even in a desert.
• Hawaii does not have any of these plants, although other plants that cause a skin rash are found on the islands. For example, mango trees grow in Hawaii, and the skin of mangoes contains the same allergenic oil (urushiol) as these plants.
• These plants do not grow in Alaska, and they are rarely found in the rainforests of Washington state and Oregon.