By Robert Gaitan
An encounter with poison ivy…is memorable. The pain and discomfort will leave the image of the vine permanently etched onto your consciousness. On a trip to visit family in Maryland, I ran across the vine while helping clear debris. I had been warned about the plant and I was careful around the vine I saw. I had not given too much thought about where the vine had been, where it had dropped leaves, where the oily leaves had come into contact with my clothes, and where my sweat was spreading the oil around my neckline, down my back, and down my arms.
It was about a two-week ordeal. Remedies help in the short-term but I have learned to just bear with it. And though the first encounter taught me plenty, I have run into poison ivy again and again. Something about the east coast and its environment is ideal for this plant. The tall trees and understory remind me of east Texas where poison ivy is known to exist. It is an environment notably different to the Rio Grande Valley.
On a recent nature walk, I ran across an interesting vine. It had a very distinctive look but I was not in Maryland, I was in Cameron County. I ran it through iNaturalist to identify the plant and, sure enough, it came back as Eastern Poison Ivy (Toxicondendron radicans). A day later, someone online confirmed its identification but I still checked with one of our valley experts on native plants and he agreed with the ID.
Though the plant had been right in front of me and had been confirmed, I still could not believe it. We do not grow up in the valley being warned to stay away from poison ivy. We know to stay away from things that poke and prick us, and others that will irritate, but not poison ivy. I had heard, as an adult, the mnemonic rhyme, ‘leaves of three, let it be’ as a reminder to watch out for this vine, but not as a youngster in the valley.
I was reminded that poison ivy is in our favorite RGV native plant book, Plants of Deep South Texas by Ken King and Dr. Alfred Richardson. I may have noticed it once upon a time, but poison ivy isn’t supposed to be in the RGV.
Rereading their comments, the authors point out the RGV would certainly be outside the vine’s normal habitat and the vine had only one significant report within Cameron County. It should not be something we should worry about.
But here was the plant right in front of me.
As the authors suggest, it is likely the nursery trade, a plant purchased somewhere else, that brought the plant to the valley. Unlike east Texas, where pollinators like the ivy’s flower and birds eat the fruit and spread the seeds, it is difficult for poison ivy to get a hold in the valley through natural means. Over thousands of years, poison ivy simply had not spread outside its normal range. We have changed the RGV such that poison ivy is here.
While no, not all vines with three leaves are a problem, it is still a good idea to be aware. Leaves of three, let it be!
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