A Native Plant You Don’t Want in Your Garden

By Kathy Conner Cornell VCE Southside Master Gardener If you’ve been reading these articles for a while, you know that I am a big fan of native plants. But there is one that causes me no end of suffering. That would be poison ivy, Toxicodendron radicans. As I sit covered in poison ivy rash, let me explain how I got in this predicament.
Poison ivy has a beautiful fall color but it is still potent at this stage. Enjoy the color from afar. Photo by Steve Dewey, Utah State University There was a large patch of irises that I passed by coming into town. I knew they needed dividing or they would either bloom sparsely or not at all next spring. I got the owner’s permission to dig them up and use the opportunity for learning moment since bearded iris are unique in the way to divide them and the way to plant them. I am the queen of pointing. I managed to rope my husband and another Master Gardener into digging the patch up. The patch was loaded with poison ivy. They did all the work and I pointed but I broke out with the rash over my legs and arms. Remember the Coasters song that said “You’re going to need an ocean of calamine lotion”? I have had a long history with poison ivy rash and for me alcohol is the treatment that dries the rash up best. I rub it on the outside and put a cold one on the inside (don’t tell Dr. Scearce). My stepdaughter told me that vinegar will lessen the itch. My husband and I took a little trip to the Bavarian Inn and here I am relaxing by the infinity pool smelling like a Thrashers French Fry (the best fries in OC, MD that you sprinkle liberally with salt and vinegar). But it did help. Poison ivy will grow pretty much anywhere. It is unique in that the leaf shape can change from plant to plant. The compound green leaves are alternate consisting of three leaflets. The leaflets can be smooth or toothed, rounded or pointed and glossy or dull. Leaflets are either smooth or hairy beneath. The leaves turn bright red-yellow in fall. The flowers are an insignificant greenish-white but the pollinators love them. Waxy, creamy-white to yellowish-white berries ripen in late summer and persist into winter. The birds feed on them and help spread the plant. What is scary is that you needn’t touch the plant to get the rash. You can get it from your dog who just ran through a patch or even a garden rake or worse yet, if it is burned. It is native throughout the United States except California and much of southern Canada in a large variety of locations, it will grow pretty much anywhere. It can be a bushy, erect or trailing shrub or a woody climbing vine. All parts of the plant contain a toxic plant oil called urushiol which cause skin irritations in most human beings. A hundred year old specimen in an herbarium can still cause a rash. Birds, reptiles, deer, and amphibians can eat the plant and its berries and also use the plant as shelter with no side effects. According to the study by Duke University Free-Air CO2 Enrichment, “high-CO2 plants produce a more allergenic form of urushiol. Our results indicate that Toxicodendron taxa will become more abundant and more “toxic” in the future, potentially affecting global forest dynamics and human health”. Scary thought right there. CO2 levels were 315 ppm in the 1950’s and the most recent NASA reading at the Mauna Loa Observatory in Hawaii was 414.47 ppm, primarily caused by fossil fuels. Does poison ivy have any assets? Yes, a few. Some birds feed on the fruits. A variety of insects feed on the flowers of poison ivy too – from beetles to flies, bees, wasps, ants, and butterflies. Due to its wildlife benefits, it can be left alone in areas with low human activity. In the Native America Ethnobotany tome, the Cherokee made a decoction of the leaves to induce vomiting. The Kiowa tribe rubbed broken leaves over skin eruptions or boils. The Navajo used it to poison arrows – that use I get. Back in 2012, I took a medical plant walk with Vicki, the Educational Director at the Staunton River Battlefield State Park. She said most of her discussion was from the Resources of the Southern Fields and Forests by Francis Peyre Porcher. She said poison ivy was used to treat paralysis and it oozes a black oil that was used for ink. According to the New England Wildflower Society, “Field experiments have shown that poison ivy is tolerant of being inundated by wastewater and could be potentially be used to treat sewage”. As I ponder how the British gave us the love of lush green lawns, it gives me a laugh to think that we sent them seeds to use poison ivy as an ornamental, mostly because of the fall color. The VCE Halifax Extension Office is now open. Masks and social distancing are required. If the door is locked, please knock. If you have gardening questions, you can continue to reach an Extension Master Gardener or Extension staff member by sending an email to wmccaleb@vt.edu or calling the Halifax Extension Master Gardener Help Desk at (434) 830-3383. Be sure to give us your first and last name, telephone number and the nature of the call. The Help Desk phone is routinely checked. Someone will get back to you, although it may be from a different telephone number. Our Covid transmission rate is in the red, so consider getting vaccinated and remember, leaves of three, let them be.