Did you know that humans are pretty much the only animals who get severe skin reactions from Poison Ivy? Many other animals not only tolerate the plant, but are fed and nourished by it. Poison Ivy (Rhus toxicodendron or Toxicodendron radicans) is a native North American plant that serves an important role in various ecosystems. Among modern humans, though, it often garners a sense of loathing and dread, since the plant seems to harm us rather than benefit us. I admit I’m pretty tired of seeing it everywhere in the Wissahickon and Fairmount. But ultimately, the goal of this article is to allow knowledge, understanding, and humility to transform the hatred, anger, and fear into a kind of deep respect. That respect will, of course, include eco-friendly ideas for coping with it on your property, how to avoid the rash, and what to do if you have been exposed.
History, Botany, and ID
It behooves us to understand some botanical history and the roles of Poison Ivy (PI) in the ecosystem. PI is part of the Anacardiaceae family, commonly known as the cashew family. Other members of this plant family include mangoes, pistachios, and the urushi tree (Toxicodendron vernicifluum), which provides sap used in creating Japanese lacquerware. This sap contains the urushiol oily resin, the very same substance found in Poison Ivy. It is the urushiol that causes that horrible rash on human skin. More on this invisible spreader below.
PI is a robust and resilient plant with many variations—it can take a shrubby, vining, or ground cover form and the leaves can also vary in their appearance. “Leaves of three, let it be,” is a pretty good reminder, but you should specifically look for the middle leaf on a slightly longer stem, jagged edges (though some may not be very jagged at all or look more like a mitten), and possibly a reddish stem. The vining type is very common in the eastern U.S.—look out for hairy stems/aerial roots climbing up trees and fences, which are just as poisonous as the leaves.
One last weird piece of history: William Bartram (whose last name you may recognize from Philly’s Bartram’s Garden), listed Poison Ivy seeds in his late 1700’s catalogue of “American” plants he would sell to plant-collectors in Europe. Apparently, some people did, in fact, find ornamental value in this dangerous plant.
Food and Function
Many animals consume various parts of PI, including the leaves, stems and berries. Animals who enjoy this food source include rabbits, goats, bears, deer, raccoons, muskrats, robins, crows, bluebirds, quail, woodpeckers, wild turkeys, and a variety of insect pollinators.
We know that Poison Ivy often shows up in disturbed soil, and because it can cause such an uncomfortable rash for humans, an interesting theory is that PI serves as a sort of “keep out” sign. It makes us more cautious, slow, hesitant—less eager to enter a particular area of the woods where PI abounds. That place needs time to heal, perhaps. For me, that caution is also respect. It requires me to hone my observation skills and look around carefully. It means I don’t get to touch or take just anything I want from the land. If I want to walk barefoot in the woods, I must heed the “keep out” signs vigilantly.
But perhaps more fascinatingly, did you know that increasing levels of of carbon dioxide in the atmosphere generally cause growth enhancement in vines? A six-year study at Duke University showed this to be especially true for Poison Ivy—elevating levels of CO2 in the air are responsible for increasing the growth rate, biomass, and allergenic intensity of urushiol in PI.
Wow, we knew the CO2 was bad for climate change, but who knew it was also making PI grow bigger, stronger, and more allergically potent?! If you needed yet another reason to fight for green policy and culture changes individually, community-wide, nationally, and globally–there you go.
Managing PI on your Property
It can be a real bummer to discover Poison Ivy on your property, especially in areas where you or pets or children may wish to play or walk, or in areas where you’d like to be planting desirable plants or otherwise maintaining a garden. Here at Eating for the Ecosystem, we aren’t in favor of using chemical herbicides to kill the plant. If you are really set on clearing a given area of PI, the methods we usually employ are as follows:
-For smaller areas or single plants, dig out the plant by the root if you can (be sure to see precautions below, and work very carefully).
-For larger areas, you might first attempt to dig out as much as you can, while wearing protective gear. Consider a painter suit or nonporous clothing to shield your skin. Then, you can lay a sheet of black plastic over the designated area to continue to inhibit growth of any vegetation in that area. Over time, without sun or water, the plants should die. You should still exercise caution when digging or planting in that area later, in case any roots were left behind.
Thinking again about the scientific findings on PI growth, continuing to find ways to reduce CO2 emissions and improve carbon sequestering in soil can help halt the rapid spread and proliferation of PI.
Precautions and Post-Exposure Remedies
- Observe and actively look for PI nearby; identify where it tends to grow.
- Do not touch any part of the plant with bare skin.
- Do not burn PI— the smoke can irritate the lungs.
- If the plant must be touched, use thick non-porous gloves and either wash them well when you are done or discard them if disposable.
- Be careful to avoid letting your clothing, backpack, cellphone, tools, etc. touch the plant—the oil can get on these objects and be subsequently transferred to your skin. The urushiol can stay on surfaces for up to five years if not washed off properly! If you know any objects or clothes brushed a part of the plant, wash thoroughly. Use rubbing alcohol to wipe down tools and phones, etc.
- Be careful on rainy days; water dripping off of a poison ivy leaf can contain urushiol in it.
- Be careful if intending to touch or harvest a plant dwelling nearby a PI plant.
- If you know your skin has touched any part of the plant, wash immediately (within the first 10 minutes) with Tecnu or similar product. You can also wipe skin with rubbing alcohol. If that is not available, it can also be effective to wash in a cold creek— use sand or silt granules to rub the skin as you wash, this will more effectively dislodge the oil.
- Jewelweed is a plant that often grows near PI and is the most effective remedy. The sooner you use it the better (you can just mash it up and rub it on the area you think was exposed).
what to do if you get a rash
- Jewelweed is also effective if you already have a rash. I’ve had success turning it into a green paste (blended with other goodies like plantain and witch hazel) and applying it every night to the affected area. I then wrap the area in gauze so that the paste doesn’t get anywhere else, and also so that I do not scratch the blisters.
- Even if you don’t have jewelweed and opt not to make your own natural remedy, store-bought remedies like drying Calamine can be helpful.
- In all cases, I have found wrapping the rash with gauze to be the most effective way to stop me from scratching the blisters. Less scratching also makes it less consistently itchy.
- Try homeopathic pills to reduce the severity of the symptoms (I use Hyland’s brand), which contain tiny amounts of Rhus toxicodendron. This is not the same as the folks who will tell you to make yourself immune by eating parts of the plant. People do that, and it works for some people, but it also has led to bad situations for others. I don’t recommend this method as of now, but then, I haven’t tried it myself.
- Once again, make sure you have washed everything well, including your entire body and any clothing and objects that may have contacted the plant directly or your skin after you had touched the plant.
- For those with severe allergies or with very large areas of rash, seeking medical attention may be your best bet. If you have access to a doctor you trust, seeking their help and advice is recommended.