Poison Ivy

Toxicodendron radicans


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

Anacardiaceae (sumacs)


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. Leaflets take on different textures and hues as the season progresses; they turn red, orange, or yellow in fall.

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.

Similar species:

Eastern poison oak (T. pubescens) is a closely related species. It occurs in low-nutrient, sandy or rocky soils, such as in glades, openings of dry upland forests, sand prairies, sand savannas, and roadsides, but it is uncommon and limited to the southern part of the Missouri Ozarks and the northern part of the Bootheel Lowlands (extreme southern and southeastern Missouri). Poison oak does not climb and does not produce aerial roots, and its leaflets usually have 3–7 deep, relatively rounded lobes, so the leaflets resemble the leaves of white or blackjack oak. The berry-like fruits have inconspicuous hairs.

There is a plant called “poison sumac,” but although some people have used that name for Missouri species, it technically belongs to a plant that does not occur in Missouri. True poison sumac (T. vernix) has feather-compound leaves with 7–13 leaflets whose margins are entire (lack teeth or lobes); it occurs in swamps and bogs to the east and north of our state.

Three other common Missouri plants are often mistaken for poison ivy:

  • Fragrant sumac (Rhus aromatica) has 3-parted leaves, but the terminal leaflet lacks the distinct stalk found in poison ivy, and the berries are reddish and fuzzy.
  • Box elder (Acer negundo) has leaves with 3–7 leaflets, but the leaves are opposite on the stem rather than alternate as in poison ivy.
  • Virginia creeper (Parthenocissus quinquefolia) climbs like poison ivy, but it usually has 5 leaflets instead of 3, and it has blue berries. (Seedling virginia creeper plants may have only 3 leaflets, however.)
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.
  • Flower and fruit clusters are loose, drooping, and axillary (arise from leaf bases along stems, as opposed to only developing at the tops of stems).

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


Image of poison ivy
Poison Ivy
Poison ivy is commonly confused with other plants, such as box elder, fragrant sumac, and Virginia creeper. Notice that poison ivy has three divided leaves, with the center leaflet on a longer stalk. It also produces white, waxy berries along the stem in summer.


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 plant showing yellow fall color
Poison Ivy Fall Color
Poison ivy turns brilliant yellow, orange, or red in the fall and contributes to the beauty of our autumn landscapes.


Photo of poison ivy, new growth, climbing on a tree trunk.
Poison Ivy, New Growth
Poison ivy's young leaves are soft and lightly hairy when they're young. By midsummer, they start looking more leathery and shiny.


Bright green poison ivy growing on a tree
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




Poison ivy is in the same family as sumacs, and this family also has several economically important fruits and nuts, including pistachio, mango, and cashew. To some degree and in at least certain parts of the plants, all contain urushiols — the same chemicals that cause dermatitis from poison ivy. One reason why cashews are so expensive is that the process of shelling them releases a caustic resin that can cause skin to blister.

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, or sometimes orange or yellow. As leaves fall from trees, their bright red, poison-ivy-clad branches can be rather pretty . . . from a distance!

Ecosystem connections

The white, waxy berries are a popular, and important, 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.