Poison ivy (Toxicodendron radicans
) is a common plant that can be either a vine or a shrub. A chemical, urushiol, in the plant’s sap may cause irritation, a rash and/or swelling in people. All parts of the plant contain urushiol and damaging them may cause the sap to come in contact with people’s skin, but the sap may also be transferred to people indirectly through pet fur or other means. If poison ivy plants are burned, this chemical can be transferred through the air, too. Breathing urushiol is dangerous. Learning to identify poison ivy is key to avoiding contact with it.
What Does It Look Like?
The appearance of poison ivy is somewhat variable. Both vine and shrub forms occur. The leaves are compound and arranged alternately (not across from each other) on the stem. There are three leaflets per leaf with the central leaflet on a longer stalk than the other two leaflets. The leaves may appear to be shiny or oily. The leaf edges may or may not have a few teeth, but they are never saw-toothed or divided into many scallops. Leaves turn red, yellow or orange in the fall. New leaves may also be red or shades of red.
How Big is It?
The vine form can be about 60 feet long. The shrub form may be two to four feet tall. The plant can also be very short.
Where Does It Live?
Poison ivy grows in fields, woods, along streams and lakes and in disturbed areas throughout Illinois.
How Does It Reproduce?
This species blooms from May through July. Flowers are green-white to white. The flowers develop in clusters at the base of the leaves. Pollinated flowers produce white, spherical fruit. The fruit is about one-fourth inch wide. Poison ivy can also spread without producing fruits through vegetative (asexual) reproduction.
What Does It Eat?
This plant doesn’t really “eat” anything! It makes its own food from carbon dioxide and water in the presence of sunlight and chlorophyll in the leaves. The resulting glucose, a simple sugar, is used by the tree for its energy needs.
Does Anything Eat It?
White-tailed deer (Odocoileus virginianus) eat the plants. Birds and other animals eat the fruits and disperse the seeds in their wastes.
What Else Should I Know About It?
• Urushiol helps the plant retain water.
• There are four key traits to identifying poison ivy: compound leaves with three leaflets; each leaf has its own connection to the main stem; alternate leaf arrangement along the stem; no thorns.
• “Leaves of three, let it be” is a common saying to help you remember what poison ivy’s leaves are like. There are other plants with three leaflets, though, so also look for hairy vines (aerial roots along the vine appear hairlike) and white, spherical fruits.
• Poison ivy climbs by sending out many short, aerial roots, or rootlets, that attach it to the tree or other structure it is growing on.