You have probably heard the saying “Leaves of three (Leaflets three)-Let it be” when describing poison ivy, but do you really know anything about this poisonous plant? Many people do not recognize this plant even though it is found throughout most of the United States, and can cause severe skin inflammation, hives, and water blisters.
Poison ivy is not an ivy, but a member of the cashew family. The plant may grow as: 1) a woody vine attached to trees or objects for support, 2) a trailing shrub mostly on the ground, or 3) an erect woody shrub entirely without support. Poison ivy may grow in deep woods or dry exposed soil, and can climb posts or trees to considerable heights. Sometimes the plant grows in among other harmless plants. Poison ivy almost always consists of three leaflets. One three-part leaf leads off from each node on the twig, the center leaf having the longest stalk. Leaves never occur in pairs along the stem. Flowers and fruits grow in clusters, and the berry-like fruits usually have a white, waxy appearance. The fruit is especially noticeable after the leaves have fallen. Poison ivy is often confused with Virginia creeper, which has five leaves radiating from one point of attachment.
Very few people are immune to the plant’s poisonous sticky oil, known as urushiol. Urushiol is found in all parts of the plant, and the danger of poisoning is greatest in spring and summer. Poisoning usually is caused by contact with some part of the bruised or cut plant, as actual contact with the poison is necessary to produce dermatitis. A very small amount of the oil can produce severe inflammation of the skin. The poison is easily transferred from one object to another (garden tools, shoes, automobile door handles/steering wheels, etc.). Clothing can become contaminated and is often a source of prolonged infection. Dogs and cats (they are not affected by poison ivy) frequently come in contact with the plants and pass the poison onto people. Smoke from burning poison ivy is extremely toxic and can cause severe cases of poisoning. Even dead plants can remain infective. The time between contamination and first symptoms varies greatly with individuals and conditions and previous exposure. The first symptoms of itching or burning sensation may develop in a few hours or a few days. The itching and subsequent inflammation usually develops into water blisters under the skin. Severe infections may cause more serious symptoms, sometimes requiring hospitalization.
Certain measures can be taken to eliminate or limit exposure to the oil. Some protection can be obtained by using protective creams or lotions. Gloves also provide protection as long as you do not contaminate yourself taking them off. Urushiol can penetrate the skin in minutes. If contact with poison ivy, or a contaminated article or item does occur, wash the contaminated parts of the body immediately with soap and water. Soap is required to help remove the toxic oil from the skin. Lather and rinse the infected areas repeatedly. Time is important, and the sooner the oil is removed from the skin, the less likely a reaction will occur or if a reaction does occur the less likely it will be severe. Always contact your health care provider if you know you have been exposed to poison ivy and develop symptoms of itching, inflammation, hives, or watery blisters.
Photo: Jennifer Anderson @ USDA-NRCS PLANTS DATABASE