LEAVES OF THREE: POISON IVY AND ITS SNEAKY LOOKALIKES
Wow, did I learn what poison ivy was the hard way, as so many of us do.
Years ago, I was clearing English ivy vines in the wintertime, in short sleeves, in an overgrown part of my yard while living in Atlanta. Since there were no leaves showing except the evergreen ivy, I assumed I was in the clear.
I was not in the clear.
Poison ivy was apparently all over the place and, by the end of the afternoon, it was all over me too. That night, it looked like I had been whipped with switches. I had welts up and down both arms, angry and itchy beyond belief.
At the time, my job required me to show up in pantyhose and pantsuits, looking like a professional adult with her life together. I remember wrapping my arms and legs in elastic bandages like some creature out of a low-budget zombie movie, desperately trying to hide the carnage underneath my very grown-up work clothes.
I was beyond miserable. I eventually ended up in the emergency room getting steroid shots because I was genuinely concerned I might claw my own skin off in my sleep. Needless to say, I have never knowingly touched poison ivy again. In fact, I give it such a wide berth that I now feel it is my sacred duty to shout, “POISON IVY!” anytime I see it growing beside a trail. Somebody has to warn the people. It might as well be me.
Which brings me to the actual point of this article.
“Leaves of three, let them be” is a genuinely good rule of thumb. More accurately, it’s leaflets of three, but that admittedly doesn’t roll off the tongue quite as nicely. Either way, I have no doubt the little rhyme has saved countless hikers from an itchy evening.
But here’s the plot twist nobody tells you about! Not every plant with three leaves is poison ivy, and not every plant capable of making you miserable has three leaflets. Ha! Mother Nature, as it turns out, doesn’t care one bit about making this easy for us.
What prompted this entire post was a spot on my daily walk where three different vines grow together… poison ivy, hog peanut, and virgin’s bower. They’re practically holding hands, like they’re all in on the joke.
Hog peanut (Amphicarpaea bracteata) is a harmless native vine with three leaflets and pretty little pale lavender flowers. It doesn’t look much like poison ivy at all, but if you’re looking only for “leaves of three,” it can certainly make you stop and look twice.
Virgin’s bower (Clematis virginiana), a native clematis, is trickier. Its leaves commonly have three toothed leaflets, and when you’re moving down a trail and not studying every plant like a botanist, it can bear a fairly convincing resemblance to poison ivy. It’s basically the solid winner of the poison-ivy-lookalike world. But even more mischievously, virgin’s bower isn’t poison ivy, but that doesn’t mean you necessarily want to rub it all over yourself either. Like other clematis species, its leaves and sap can cause skin irritation in some people.
So in this particular patch of forest, we have poison ivy, a harmless three-leaflet vine, and a three-leaflet poison-ivy impersonator that can also irritate your skin.
Well played, Mother Nature.
Meanwhile, poison ivy itself is a total shapeshifter. It can creep along the ground, grow more shrub-like, or climb trees as a thick, hairy-looking vine. Its leaflets vary tremendously too. They can appear glossy or dull, and their margins can be relatively smooth, toothed, or lobed. They can be small and reddish or quite large. No wonder some people have a hard time identifying it!
And one of the lessons I learned so memorably all those years ago is that poison ivy does not need leaves to ruin your week. The urushiol responsible for the rash is present in the vine and other parts of the plant, too. So that hairy vine climbing a tree in the dead of winter deserves just as much respect as those shiny green leaves in July.
Poison ivy isn’t the only culprit worth knowing either. Poison oak and poison sumac contain the same harmful oil, urushiol, despite looking quite different from poison ivy. Poison sumac, for example, doesn’t have three leaflets at all. So “leaves of three, let them be” is a useful starting point. It is definitely not the entire rulebook.
I also hear people confidently announce that they are “not allergic to poison ivy.” And look, that may genuinely be true for them right now. But sensitivity to urushiol can develop or change with exposure, so I wouldn’t recommend using your bare flesh as a diagnostic tool. My personal advice is to admire poison ivy from afar and allow it to continue its botanical existence without involving your epidermis.
There’s another sneaky thing about urushiol worth knowing, especially if you’re a hiker or a backpacker. The oil doesn’t stay politely contained to the plant itself. It can be transferred to clothing, gloves, tools, gear, and even an animal’s fur. Which is exactly the kind of fact that can turn a normal hiker into a slightly paranoid freak after one sufficiently traumatic incident. Even trekking poles can become part of the conspiracy.
When I’m backpacking and I know I’ve been walking through an area thick with poison ivy, I wipe down the lower sections of my poles off when I get to camp. I typically need my trekking poles to pitch my tent, and the last thing I want is to unknowingly transfer urushiol from a pole onto my tent, hands, and eventually onto my face while I’m setting up camp.
Experience has taught me that poison ivy deserves respect, but it doesn’t require fear. Learn your lookalikes. Learn to recognize more than just “three leaves.” Pay attention to the whole plant, including how it grows, the shape and arrangement of its leaflets, its flowers, its vines, and where you find it. And when you’re not sure? Give it a little space.
And if you ever see me on the trail suddenly yelling “POISON IVY!” at a completely random patch of vegetation, just know I’m doing it out of love. And a very healthy respect for what happens when you don’t.
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