There are a great many plants that we avoid for obvious reasons. When choosing what I want to plant in my own yard, I shy away from trees with messy seed pods and shrubs that send up excessive suckers. But there are other undesirable plants that have a tendency to find us, despite how we avoid them.
Poison ivy, poison oak, poison sumac and thorny smilax are all plants that we purposefully avoid, for good reason. Properly identifying these species can keep us out of a lot of trouble, as toxins present in these plants can reek havoc on our bodies.
So while strolling through the woods this past fall, I began to ponder the value and purpose of these plants we tend to hate. If all native plants have an ecological purpose, then what is theirs? Surely the forest has uses for these plants that we have grown to hate.
Before exploring the native ecological value of these plants, it’s pertinent to explore where each grows and the differences between them. Poison Ivy and thorny smilax are both very common in the North Carolina Piedmont. Poison oak is more prevalent toward the North Carolina coast. Poison sumac is most commonly found in swamps and boggy areas. So for the purpose of this exploration, we’ll just focus of poison ivy and common types of smilax.
Poison ivy is native to the Eastern United States, and was at one time thought to be an intriguing plant with both landscape and medicinal value. In the late 1700s, Quaker farmers and wild plant enthusiasts John Bartram and son William were collecting seeds and plants and shipping them overseas to Europe. In addition to oaks, poplars, and pines, the Bartrams were also sending poison ivy.
Although known for its toxic properties, gardeners in Europe saw poison ivy as both an attractive landscape vine and an opportunity for medicinal study. It is said that Josephine Bonaparte grew poison ivy and poison sumac in her gardens near Paris in the early 1800s.
Medical publications during this time period speak of poison ivy’s medicinal qualities. One study suggested that ingesting a tea of boiled poison ivy leaves could heal external skin problems. Most studies of poison ivy’s medicinal qualities have focused on skin maladies, such as blisters and rashes.
So wthough there may be some healing properties hiding within the leaves, stems and berries of poison ivy, I would not recommend investigating that yourself. Nor would I suggest you purposefully plant some in your yard. But if you’ve got some hanging out on your property, it’s not necessarily a bad thing.
Birds, insects and wildlife all benefit from the presence of poison ivy. Plant ecologist and native plant enthusiast Lisa Gould offered a few examples of how poison ivy and other undesirables nurture the ecosystem.
“Poison ivy and poison sumac are pollinated by bees, flies, and some beetles, which also eat the pollen and nectar,” Gould said. “The fruits are high in oil and some vitamins, and are eaten by many birds and small mammals. More than 60 species of birds are known to eat poison ivy fruit, and apparently birds are the major dispersers of the seeds, which pass through the digestive tract unharmed.”
Another plant you’ve surely seen but may not identify with as easily is smilax. Gould pointed out that there are 14 species of smilax in North Carolina, some with thorns and some without. Smilax has become an undesirable plant for many because of the jagged and prolific thorns that cover the vining stems.
While not poisonous to the touch, smilax a mean and tenacious plant, so it often gets a bad rap. Gould explained that smilax rotundifolia and smilax glauca are commonly found in our area. Smilax walteri is more common on the coastal plain.
Adorned with a slew of common names, I most often refer to the thorny vine as saw brier. Gould said that smilax walteri has many nicknames, which all illuminate its thorny nature.
“There are lots of colorful names for smilax, especially the thorny ones,” Gould said. “Greenbrier, catbrier, bullbrier, horsebrier, tramp’s-trouble, hellfetter and blaspheme vine among them. Tangles of these vines make good cover for birds and small mammals, and the young shoots, leaves, and tendrils are browsed on by deer.”
“People have had various medicinal uses for the rootstocks, and the fruits can be used to make a blue dye. The fruits are low in fat, so birds and small mammals don’t tend to eat them until later in the season — but they can be an important late winter early spring food sources.”
We all know the importance of native plants, and their roll in local and global ecosystems. So the next time you spot some poison ivy, thorny smilax or undesirable native plant on your patch of earth, pause and consider its role. If it’s not posing a problem, then let it be. There’s a purpose for even the most hated plants.