Habitat:
Poison ivy can be found on a wide variety of sites from moist and shady to open and dry. Across this wide range of habitats it most frequently occurs in shady forests.

Size/Form:
It grows as a high-climbing woody vine or a small shrub that grows along the ground. Poison ivy vines climb up trees by aerial roots and grow up to 150' in length. Branches from the vine may deceptively look like branches of the tree. Poison ivy shrubs grow from 1½' to 6½' high.

Stem:
New stems are gray-brown and hairy but they gradually turn hairless with age. Older stems can be 2" to 4" wide.

Leaves:
The leaves are compound, alternate, and deciduous. They have three leaflets that are usually 2" to 8" long and 1" to 5" wide, and ovate to elliptic in outline. The thin leaflets have entire to serrate to shallowly lobed margins and the lower leaf surface is light green and slightly hairy. The leaves usually have a longer, symmetric, terminal leaflet often with one lobe on each side of the leaflet. The two, asymmetric leaflets on opposite sides of the terminal one have a single lobe so they look like mittens with a thumb.

Fruit:
The fruit is a dry, round drupe about ¼" wide, tan or whitish, and grooved. The seeds have an oily covering and are primarily dispersed by animals. Since the covering is buoyant, the fruit is also dispersed by waterways.