Poison ivy: The scourge of summer

Authored By Jenni Frankenberg Veal

Once again, summer beckons with its palette of green, luring those with an affinity for the woods into her warm embrace. However, Mother Nature likes to keep things interesting, and the similarity between poison ivy and Virginia creeper is one example of her complexity.

Anyone with a desire to dabble in the woods should learn to differentiate between Virginia creeper and poison ivy. These tricksters grow alongside one another in woods, fields and along roadsides and riverbeds, and both have dark green leaves that turn red in the fall. Virginia creeper holds respectable status as a native groundcover, while poison ivy is known as the “scourge of summer.” 

“People get Virginia creeper and poison ivy mixed up because they look so similar-the leaves look alike, and they grow in the same environments,” Christine Bock, lead horticulturist at the Tennessee Aquarium, said. “We have Virginia creeper planted in the aquarium, and I have had to convince some visitors that we have not planted poison ivy in our exhibits.”

Poison ivy’s problematic status stems from its production of urushiol, an oil found within the sap of the plant that causes contact dermatitis in most people who touch it. The oil is present in all parts of the plant: the leaves, stems, flowers and berries-and even the dense, hairy aerial roots that climb trees contain urushiol. (One tip for remembering what poison ivy looks like: Hairy rope, don’t be a dope!)

Exposure to 50 micrograms of urushiol (less than one grain of table salt) will develop a rash in 80 to 90 percent of adults. Exposure leads to skin blistering within one to 12 hours, and rashes last about two weeks.

Virginia creeper does not contain urushiol. However, the plant does have a dark side: Its berries are highly toxic to humans, and some people are allergic to the oxalate crystals found in the plant and may develop a rash.

A quick leaf count is the easiest way to differentiate between Virginia creeper and poison ivy. Virginia creeper has five leaves in a group, as opposed to poison ivy’s three. So before stepping into a patch of green, remember this: Leaves of three, let it be; leaves of five, let it thrive.

Poison ivy does have some redeeming qualities. Its cluster of white, waxy fruits are of particular benefit to wildlife. (Keep this in mind while hiking, as well: Berries white, take flight!)

“People want to understand the purpose of poison ivy, and I explain that its berries are a nutrient-rich source of food for birds and wildlife,” Bock said.

At least 60 species of birds are reported to eat poison ivy berries, including eastern bluebirds, gray catbirds, dark-eyed juncos, Carolina chickadees, northern flickers, eastern phoebes, white-throated sparrows, brown thrashers, the tufted titmouse, white-eyed vireos, cedar waxwings, Carolina wrens and woodpeckers. Deer also browse the fruits and foliage, cottontail rabbits feed on the twigs and bark, and its flowers are frequented by bees.

Virginia creeper’s indigo berries are also an important food source for migrating birds in the fall. Thirty species of wildlife eat the berries, including many fruit-loving birds. Virginia creeper is also the larval host plant for several species of moth, including the Virginia creeper sphinx.

Understanding what’s what in the woods can make the difference between summertime misery or fun-and modifying or destroying critical wildlife habitat.

Most property owners with pets and children choose to remove poison ivy from their grounds in order to prevent outbreaks.

“It’s generally a good idea to remove poison ivy from the ground if you have kids and animals,” Bock said. “If you dog runs through poison ivy, the oil can be transferred to you.”

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Jenni Frankenberg Veal is a freelance writer and naturalist living on Walden’s Ridge in Southeast Tennessee. She enjoys writing about the natural world and exploration opportunities found within the southeastern United States, one of the most biologically and recreationally rich regions on Earth. Visit her blog at www.YourOutdoorFamily.com.