Poison Ivy

Toxicodendron radicans

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Illustration of poison ivy leaves, flowers, fruits.
Poison ivy (Toxicodendron radicans).
Paul Nelson
Poisonous
Skin irritating
Family

Anacardiaceae (sumacs)

Description

Poison ivy is a toxic vine that climbs to 60 feet high, trailing or climbing by aerial roots. Sometimes it appears as a low, upright shrub.

Leaves are alternate, compound, with 3 leaflets (“leaves of 3, let it be”) that are variable in size and shape; the end (center) leaflet has a stalk ½–1¾ inches long, which is longer than the stalks on the other 2 leaflets; side leaflets have unequal sides.

Stems are light brown, hairy, with raised pores, climbing by aerial rootlets. Stems trail until they find support; lacking support, they assume an erect, shrublike posture with single stems.

Flowers May–June, with clusters 1–4 inches long on new growth of stems. Flowers are small, greenish white, and fragrant.

Fruit ripens August–November, berries in grapelike clusters, persistent, about ¼ inch across, creamy white, waxy, globe-shaped, usually smooth.

Key Identifiers
  • Woody vine that can have a shrubby habit or can climb up trees, utility poles, fences, etc.
  • “Leaves of 3, let it be”: Leaves compound, with 3 leaflets.
  • The end (center) leaflet has a stalk, ½–1¾ inches long, which is longer than the stalks on the other 2 leaflets.
  • The 2 side leaflets have unequal sides.
  • Leaves have a reddish tinge in spring; turn motley green in summer; turn red, orange, or yellow in fall.
  • Berries waxy (not fuzzy), white.
Size

A trailing or climbing vine that can reach 60 feet high, often growing on trees or other objects.

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Image of poison ivy
Poison Ivy

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Photo of Virginia creeper and poison ivy climbing on a tree trunk.
Virginia Creeper and Poison Ivy
Virginia creeper climbs on the left, and poison ivy climbs on the right in this picture.

Poison_Ivy_7-28-16.JPG

Photo of poison ivy, new growth, climbing on a tree trunk.
Poison Ivy, New Growth
Poison ivy's leaves take on different textures and hues as the season progresses.

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Bright green poison ivy growing on a tree
Bright green poison ivy growing on a tree
Habitat and conservation

Occurs in floodplain and upland forests, alluvial soil along streams, thickets, along fence rows, roadsides, and railroads. Birds often distribute the seeds via their droppings. To control poison ivy, spraying with glyphosate such as Roundup is recommended over burning. (Burning poison ivy causes its oil to vaporize and become airborne, which can cause severe rashes; people breathing the smoke may have to be hospitalized.)

image of Poison Ivy distribution map
Distribution in Missouri

Statewide.

Status

Common.

Human connections

Poison ivy’s toxin is an oil that on many people causes an itchy rash with clear blisters. If you touch poison ivy, change clothing and immediately wash the affected area with soap and cold water. The oil can remain on fabric until it is washed off.

In fall, this plant’s leaves often turn attractive red. As leaves fall from trees, the bright red, poison-ivy-clad branches can be rather pretty . . . from a distance!

Ecosystem connections

The white, waxy berries are a popular food for songbirds during fall migration and in winter when other foods are scarce. Many birds like the berries as well as the insects hiding in the tangled vines. Small mammals and deer browse on poison ivy foliage, twigs, and berries.