Poison ivy (Toxicodendron radicans).
Paul Nelson
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Poison Ivy
Toxicodendron radicans
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.
poison_ivy.jpg
Poison Ivy
Virginia_Creeper_Poison_Ivy_7-28-16.JPG
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
Poison Ivy, New Growth
Poison ivy's leaves take on different textures and hues as the season progresses.
forest-grazing6-poisonivy.jpg
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.)
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.
Similar Species
Fragrant Sumac
Rhus aromatica
Box Elder
Acer negundo
Virginia Creeper
Parthenocissus quinquefolia
Trumpet Creeper (Trumpet Vine)
Campsis radicans
About Trees, Shrubs and Woody Vines in Missouri
There are no sharp dividing lines between trees, shrubs, and woody vines, or even between woody and nonwoody plants. “Wood” is a type of tissue made of cellulose and lignin that many plants develop as they mature — whether they are “woody” or not. Trees are woody plants over 13 feet tall with a single trunk. Shrubs are less than 13 feet tall, with multiple stems. Vines require support or else sprawl over the ground.
