Poison Ivy

Toxicodendron radicans
Anacardiaceae (sumacs)

A poisonous vine that climbs to 60 feet high, trailing or climbing by aerial roots. Sometimes it appears as a low, upright shrub.

Leaves 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.

A trailing or climbing vine that can reach 60 feet high, often growing on trees or other objects.
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.
Distribution in Missouri: 
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 turn attractive red.
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.
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