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Outdoor advice from our resident expert

Drawing by Chandu Tennety

Hey Doc: I hear that poison ivy is everywhere! All I see is green stuff on the trail. What does it look like, and how do I know I have it? How do I get rid of it?- Itchy Scmitchy

Dear Itchy,

Poison ivy (Latin name Toxicodendron radicans, but known to many as PI) is a common sight on roadsides, along tree trunks, trails, forest roads and in my own back yard! It is a woody vine that can grow in thickets or climb up a tree. It flourishes anywhere there’s enough sunlight to give this creep(er) a place to grow. I’d be remiss if I didn’t repeat the mnemonic “leaves of three, leave it be” – because each leaf is made of three leaflets. The real giveaway is that those leaflets have irregular leaf margins – look for a notch along the edge.

Here’s the sticky business. What causes the rash is the oil-loaded fine hairs on the surface of the plant. This oil, called urushiol, can be spread around from the roots and stems of the vine too, so you can get PI rash in the winter (when the leaves are gone). So be careful when you lean on that weird hairy vine growing up that tree!

You’ll know you have it if you start itching and getting little pustules and a rash, commonly on your arms, wrists, legs, ankles – those places the green stuff touches as you hike. You can buy over-the-counter products for removing this oil from your skin and it will help you heal more quickly (check out Nature’s own remedy is the juice from the stem and leaves of the plant touch-me-not, also known as jewelweed. You’ll often find this growing near PI. Crush the jewelweed and rub it on the PI-affected area right away and you likely will never develop a rash.

Make sure you avoid petting your dogs or wash them if they have been running in an area with loads of PI. (If I could only train my dogs to ID and avoid this plant.) The only thing that spreads PI is the oil, not the goo leaking out of your skin after you’ve scratched it for the 50th time.

According to wikipedia, 15 to 30 percent of the population is immune to the plant. Perhaps these are the bold ones. An old crusty prof I know tells me “it’s the fear of the plant that produces your body’s reaction.” (Read this with a grizzled Dennis-Hopper-in-Apocalypse-Now accent.) He recommends eating a leaf the size of a squirrel’s ear at the start of every summer “to show it who’s boss.” Sounds like a recipe for a blistered tongue to me. I’ll continue to rely on some basic botany skills and it gets me by just fine.


Kim Brown is out, enjoying herself. But submit an outdoor advice question and maybe she'll check her satellite phone and get back to you.