A 2007 Canadian study with the unintentionally hair-raising title, “Incidence of Intentional Vehicle-Reptile Collisions” examined—in theinterest of local reptile species preservation—the supposition that people in the area were running over snakes crossing the road on purpose. In the study, a decoy rubber snake was placed on a road along with a faux turtle and, as a control, a styrofoam cup. Guess which one drivers ran over the most? In fact, a significant number of drivers redirected their vehicles, even crossing the center line of the road, expressly to crush the hapless “snake” with their tires.
The conclusion of the study? Some people just don’t like snakes.
What, you might ask, does this murderous iteration of human ophidiphobia (fear of snakes) have to do with Poison Oak? Well, like snakes, some of which, as we know, happen to be venomous, Poison Oak, or Toxicodendron diversilobum, doesn’t exactly pass the “warm and fuzzy” test. Both have a habit of appearing suddenly, out of nowhere, with potentially unpleasant results. Hearing, close by, the sickening sound of the rattle belonging to an invisible Western Diamondback has its botanical equivalent in that awful moment when your hand, arm, shin or face brushes up against something on the trail and you look back and see those shiny, “leaves of three” nodding in your wake. While not exactly life-threatening, such an encounter with Poison Oak is, at the very least, a classic “Oh Fuck” moment.
If, like me, you’re susceptible, Poison Oak’s resiny “poison,” called urushiol, goes to work instantly, as your skin’s contact with the leaves or stems of the plant trigger an allergic reaction. (In other words, the source of the rash is your body’s own immune system. Poison Oak is not, strictly speaking, poisonous.) This contact dermatitis can range from a minor irritation to a suppurating field of painful, fluid-filled blisters that keep appearing and popping open like little water balloons before they crust over and itch like hell. The rash can persist for weeks.
While I don’t recommend this for the faint of heart, if you’d like to see some truly gnarly cases, poison-ivy.org has a “Rash Hall of Fame.” (Fun Fact: Poison Ivy and Poison Oak, which is in the Sumac family and is not an oak, are close relatives.)
Adding insult to the injury, humans appear to be the only species for whom urushiol is an allergen. Munching on the leaves of Poison Oak (also not recommended) would likely kill you in short order, while a Mule Deer doing the same thing won’t even suffer from slight indigestion. In fact, she’ll find it a tasty and nutritious snack. Your dog, frolicking through a thicket of Poison Oak? No problem. You? Not so much.
All of which is to say, it isn’t difficult to understand why people might fear or even hate poison oak. It’s not by any means an irrational response. So why, you might ask, have I actually planted, of my own free will, this shrub that seems to harbor a grudge against humans, in my own backyard, where, three years later, it continues to thrive—without a drop of supplemental water I might add? Toxicodendron diversilobum, how do I love thee? Let me count the ways…
1. It’s Beautiful
Having entwined itself within a tangled patch of Bitter Gooseberry (Ribes amarum), my planted Poison Oak displays a vivid green against the shriveled, brown leaves and bare, thorny branches of these summer-deciduous plants. The glistening surface of the elegantly shaped trio of leaflets reflects the dappled sunlight that penetrates the Coast Live Oak canopy under which it grows. In the fall, the leaves start to turn various shades of pale yellow, orange and red before they drop, contributing some relatively rare autumn color to the Southern California fall landscape.
2. It’s Nutritious
Waxy Poison Oak berries—a creamy, off-white—ripen in the summer and are an important food source for a virtual Who’s Who of the avian world: Wrentits; Nuttall’s Woodpeckers; Spotted Towhees; the Oak Titmouse and a wide assortment of finches, to name just a few. As previously mentioned, the leaves are foraged by deer and for good reason: they’re loaded with protein and minerals.
3. It’s Missing
Now that it’s been largely extirpated from the urbanized zone of Los Angeles, other remnant native species here with whom Poison Oak co-evolved over eons (such as the highly prized Coast Live Oak (Quercus agrifolia) and Toyon (Heteromeles arbutifolia) quite literally “miss” its presence. On my property, for instance, there have always been one or two indigenous patches of Poison Oak, suggesting that it was more locally widespread before someone decided to build houses here a little over a century ago. It appears to be true that removing exotic plants from under a mature oak canopy (especially weedy, European annual grasses) is one of the most effective things you can do to support the overall health of the tree. Likewise, selectively introducing a few understory plants with whom your old oak was once “familiar” seems to have a similar effect. Individual plants’ root systems have been shown to communicate with one another through a network of subterranean soil fungi called Mycorrhizae (sometimes referred to as the “Wood Wide Web”). Plants can share and redistribute nutrients among themselves through this fungal internet and can even warn each other of insect predators in the area. I like to imagine that our native oaks “recognize” Poison Oak and react much like one might to seeing a dear old friend, one who has been missing from an important conversation for a very long time.
4. It’s transgressive
In addition to all of the above, planting Poison Oak in your own backyard will definitely establish your local native plant bona fides, separating you from the ho-hum, cultivar pack when it comes to micro habitat restoration and wildlife support within the urban zone. (Just plant it where you can admire it from a safe distance and where you—or your dog or cat—aren’t likely to brush up against it. Needless to say, Poison Oak may not be a good choice for smaller gardens or gardeners with young children.)
Finally, giving this almost universally despised plant a home in your backyard has a sociopolitical aspect, presenting an opportunity to challenge the destruction of essential biological systems that can result from the ingrained habits of anthropocentrism (the view that people are the only arbiters of what is good, important or necessary in the world).
Anthropocentrist judgements are based solely on an extremely narrow evaluation of how the thing in question can either harm or benefit human beings directly). After all, this vilified species needs all the advocates it can get.
Case in point: Several years ago, I was hiking along a canyon trail in the Angeles National Forest. From the opposite direction, I saw a pair of hikers coming toward me. One was holding a leash and walking what looked, from a distance, like a goat. As they got closer, I saw that it actually was a goat. On a leash. In the Angeles National Forest.
You can’t make this stuff up.
Anyway, we chatted briefly and, as diplomatically as I could, I expressed my concern that the seeds of exotic species might be spread in the canyon through goat droppings, an example of which were unceremoniously deposited at my feet even as we spoke. (Imported domestic livestock animals were, after all, one of the factors responsible for the swift decline—and eventual decimation—of California’s pristine, pre-European bunchgrass prairies centuries ago.) Whether or not this might have been the case, the goat’s owners seemed blithely unconcerned and cheerfully offered me their opinion that “on balance” their visiting pet goat did “more good than harm” to the environment of the canyon because “she eats Poison Oak.”
Oh, great. I’ll be sure to tell the Spotted Towhees. They’ll be thrilled.
Now if you’ll excuse me, I have to go run over a snake.
– Eric Ameria
© 2019 by LA Native Plant Source