Poison Oak, Toxicodendron diversilobum, is one plant every hiker needs to know. The shiny oils on the leaf surface can cause severe allergic reactions on the skin, a blistering rash that can take anywhere from 12 hours to 10 days after exposure to show up. Even a brush with dead leafless branches of this plant can provoke severe irritation for years after it has completed its earthly lifespan!
It grows from Baja California to British Columbia west of the Cascade Range of mountains as well as Nevada, according to the USDA Plants Database. But before we discover how to identify it, lets take a moment to consider its more appealing qualities.
What’s GOOD about Poison Oak?
Deer eat the leaves, many birds eat the fruit and towhees make nests out of it, and small mammals take shelter in this plant. The human ethnobotanical records are fascinating too and show that indigenous people have historically embraced Poison Oak in surprising ways. As I wrote in my book Dandelion Hunter, “Before there was a plant for that, there was an app for that.” Check this out:
– Mendocino people burned it over the skin as a cure for ringworm and warts! This technique is called “moxa” in herbalism. But inhaling the smoke of this plant would be very dangerous, indeed.
– Tolowa people ate flower buds in the spring to obtain immunity from the plant poisons! California survival expert Christopher Nyerges says he does the same thing and that it works for him!
– Multiple tribes made a black pigment from the burned ashes of the plant and used it for tattoos and dye!
– There’s even record of it being used topically as antidote for rattlesnake bites! (Now this is one I would not volunteer to test out!)
How to Identify Poison Oak
Poison Oak, Toxicodendron diversilobum, is quite crafty at disguise: It can change form, growing as a vine (sometimes winding its way up a tree trunk), shrub, or herbaceous plant — even mimicking a similar looking harmless plant it is growing near! And the leaf color can range from green to vibrant red.
1) Poison oak leaves have wavy, scalloped edges and are usually glossy and shiny.
2)”Leaves of 3, let it be.” Poison oak is trifoliate. It has three leaflets. One pair of leaflets is attached to the main stem directly, while the terminal leaflet (the one on the end) has a longer stem separating it from the bunch. You can see this demonstrated in the photos below.
Also, there’s a related species here in the Willamette Valley that is known as Western Poison Ivy,Toxicodendron rydbergii. It is a hybrid of poison oak mixed with western poison ivy. It looks extremely similar except the leaf edges are toothed and the shape is more oval, less wavy.
Identification can be tricky. Harmless berry vines such as blackberry also have 3-part leaves — but those are large, angular and have serrated edges. In the Pacific Northwest, the lobed, oak-like leaves of Poison Oak can be easily confused with the harmless and similar looking bushes Snowberry, Symphoricarpos albus, as well as Oceanspray, Holodiscus discolor, or the young leaves of a sprouting Oregon White Oak tree, Quercus garryana.
Lookalikes – These Are NOT Poison Oak:
If you do get exposed, what can you do?
The U.S. Center for Disease Control (CDC) says there’s a chance you may be able to remove the irritating urushiol oil by washing with dish soap and warm water, or by swabbing your skin with isopropyl rubbing alcohol. There’s also a product on the market called Tecnu that is advertised to do the same.
If it’s too late to wash it off and you find yourself with serious dermatitis, unfortunately most people say that conventional over-the-counter remedies of calamine lotion and oral antihistamine tablets do not help. Taking a hot shower can bring some temporary relief. Some people also say the rash began to heal and stop itching after they rubbed baking soda paste (mixed with water) on their rash and then showered it off, followed by applying a vinegar wash that stung initially.
What about herbal remedies?
The famous and well-loved southwestern folk herbalist Kiva Rose, co-founder/editor of the wonderful herbal journal Plant Healer, suggests as a remedy for urushiol-induced dermatitis to “apply diluted vinegar or tinctures of Mugwort (make sure you don’t have an Aster allergy first of course), Plantain, Yarrow and Rose leaf/petal. Oatmeal, Mallow and Rose petal baths can be helpful too.”
Other possible remedies include crushed jewelweed stems on the skin or a cooling aloe vera poultice.
How can you get rid of it if it grows in your yard?
Please don’t use chemical pesticides. Instead, pour boiling water on it, and/or squirt vinegar on it, and then dig up the roots, wear gloves and pull them and discard the plant (and then get rid of those gloves) — or better yet, hire a goat to eat it!
Wilderness First Aid
If you are one of those people who, like me, is looking forward to spending as much as time as possible this summer hiking and camping, but sometimes feel a little nervous about it because you don’t have wilderness first aid training and wouldn’t know what to do in an emergency, then you’re in luck, because the weekend of May 13-15 the world-renowned expert on this subject, Sam Coffman, is flying in to Portland from Texas to teach a three-day camping immersion on the subject that will get you certified in Wilderness First Aid plus 8 hours of herbal first aid training. It’s a lot of fun to sleep under the stars, have bonfires and go swimming in the Little Klickitat River. You’ll go home with confidence, plus two textbooks to keep as reference tools, one of which was written by Sam himself. The location for this experience is very beautiful and private, with a hot tub and catered home-cooked meals. You have until May 2 to sign up. Join me!
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