Poison Ivy: Friend or Foe

By Kaleb Neece
Missouri Departmentof Conservation

Have you ever taken a stroll through the woods, chased an elusive turkey, or done some yardwork only to find you have developed a rash? You may have encountered the infamous poison ivy.
Poison ivy (Toxicodendron radicans) is widespread throughout Missouri. It takes the form of a woody shrub or vine with hairy-looking aerial roots. Poison ivy can grow up to 60 feet long. The leaves typically have a glossy surface with 3 leaflets of variable 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. From the leaves to the roots the entire plant contain oil called Urushiol. This oil is what causes skin irritation and a rash. The Urushiol oil is active all year round including in the winter
So, what do you do if you come into contact with poison ivy? The best prevention is of course to avoid the plant whenever possible. A useful rhyme for remembering what poison ivy looks like is “leaves of 3, let them be”. If you do encounter poison ivy, it is best to change clothing immediately and to wash the exposed skin with soap and water. If you can wash all the oil off exposed skin within five minutes of contact, no reaction will occur. Even water from a running stream is an effective cleanser. The oil from poison ivy can remain active on clothing and footwear for up to a year, so be careful not to expose yourself to the oil again. The oil can also be transmitted on pet fur.
To get rid of the poison ivy plant the best option is to spray it with glyphosate (Roundup, Kleenup and others) according to label directions. It is not a good idea to burn poison ivy. When burned the Urushiol oils will vaporize and get carried in the smoke. The smoke can then be inhaled and cause you to have an internal reaction to the oils.
While poison ivy is a nuisance to humans, it can provide considerable value to wildlife. The white, waxy berries are a popular food for songbirds during fall migration and in winter when other foods are scarce. Robins, catbirds, and grosbeaks especially like the berries. Many birds feed on insects hiding in the tangled vines. Small mammals and deer browse on the poison ivy foliage, twigs, and berries.
Now you know how to handle poison ivy. It is time to get out and enjoy all of Missouri’s wild wonders.