Those of you who have experienced the itchy burning blisters that result from contact with poison ivy know why it is called the “scourge of summer”.
Poison ivy (Toxicodendron radicans) is a member of the sumac family, which also includes cashews, pistachios, mangos and smoke trees. It is a genetic mystery why some poison ivy plants begin to vine as seedlings and some never do. Poison ivy vines can grow into the tops of trees where their leaves can be mistaken for the leaves of the tree. They can be identified by the fuzzy-looking root hairs that help the vines cling to the tree trunk. Wild grape and Virginia creeper vines also climb trees but are smooth in appearance.
Poison ivy is a native Indiana plant that colonizes disturbed areas like fence rows, ditches, gardens, old fields and the perimeters of woods. Poison ivy leaves turn bright red in the fall at the same time that clusters of small white berries are ripening. Two little sayings can help people identify poison ivy before coming into contact with it: “Leaves of three, leave it be” and “Berries of white, best take flight.”
The culprit in all poison ivy allergies is the oil urushiol, which is found in the leaves, stems, roots, and berries of the plant. Upon contact, urushiol can bind to the proteins in skin cell membranes, which the immune system can attack. If you think you have come into contact with poison ivy, immediately take a cool shower with plenty of soap (hot water causes the pores to open, increasing the likelihood that urushiol can penetrate the skin). Blisters erupt from within 1 to 12 hours of exposure and the rash can last 10 days or more. The treatment is usually a corticosteroid compound.
How many of these true/false questions can you answer?
• You can get poison ivy by touching the rash of someone who has it.
False. Only the urushiol in the plant itself can cause an allergic reaction. Poison ivy doesn’t “spread.” Different levels of urushiol and degrees of skin contact with the plant account for the uneven appearance of a rash.
• If you have never had an allergic reaction to poison ivy, you are probably immune to it.
False again! Repeated exposure to poison ivy actually sensitizes the immune system and over time, reactions become more severe. Up to 85-90 percent of the population is eventually allergic.
• Poison ivy is an important food source for many kinds of wildlife.
True, especially for birds. Over 60 different bird species (including woodpeckers, cardinals, vireos, waxwings, warblers) love to feed on its white berries in the fall, while deer and rabbits feed at ground level.
If poison ivy has invaded your yard, you may need to apply Roundup. Don’t weed-whip poison ivy because the sap can splatter, and pulling it up by the roots is risky. On your next walk, try practicing your poison ivy ID skills!
Sheryl Myers taught biology and environmental science for 34 years. She has worked as a naturalist for Anderson City Parks as well as Mounds State Park. Sheryl is a founding director of Heart of the River Coalition and founding board member of the Red-tail Land Conservancy.