Poison ivy, the notorious cause of itchy, blistery rashes, grows throughout the continental United States and much of Canada. The plant can be found in forests and wetlands, on beaches, and along streams, as well as in urban settings such as parks, yards, and along roads. Poison ivy prefers partial sunlight, so it often grows where the land has been disturbed, such as along the edges of trails, fields, or landscaping. Both types of poison ivy spread along the ground, and eastern poison ivy also climbs trees, shrubs, walls, fences, and other structures, clinging to its host with hairy rootlets and sometimes sending out horizontal branches. Most people know the phrase “Leaves of three, let it be,” but many plants have leaves that grow in clusters of three, so it helps to know a bit more about the physical appearance of poison ivy. Each poison ivy leaf (or, more accurately, leaflet) has a small leaf stem at its base, attaching it to a stalk or small branch that connects to the main poison ivy vine. The leaflet in the middle of the threesome usually has a longer leaf stem than the two side leaflets. Poison ivy leaflets are about twice as long as they are wide. They are typically two to five inches long but may reach six or more inches if conditions are right. Poison ivy leaves may be smooth-edged or may have lobes or teeth. The two sides of the leaf may or may not be symmetrical.
Leaves may be red or green, shiny or dull. The plants may have flower buds, flowers, or berries in dense clusters close to the vine. The cause of poison ivy reactions is urushiol, an oily resin that’s found in the leaves, stems, and roots of the poison ivy plant; most people are allergic to it. Urushiol sticks to skin, clothing, fur, gardening tools, and other surfaces when it comes into contact with them. Washing the oil off your skin immediately after contact may prevent a rash from developing. Soap and water is effective, as are commercial poison ivy washes, but the key in either case is to wash the oil off quickly, before the allergic reaction begins. Following contact or even potential contact with poison ivy, you should also wash your clothing and footwear and any gear or equipment that could have touched the poison ivy plant. It’s also important to wash pets who may have gotten urushiol on their fur so they don’t pass it on to you.