Leaves of three: woes and wonders of poison oak and ivy!
It’s summertime and hopefully you Jammers are getting outside to play, swim, hike, get muddy and explore! If you’re in the US, chances are you’ve likely encountered either poison oak (Toxicodendrondiversilobum) in the western US or poison ivy (Toxicodendronradicans) in the eastern US. Upon contact, these plants can cause a nasty itchy, blistery rash–I speak from experience sadly–so it’s best to steer clear of them. An easy way to recognize them is by looking at photos and remembering this little rhyme:
Leaves of three? Let it be!!
What I find particularly interesting is that many animals consider them to be delicious food! Goats, white-tailed deer, raccoons, muskrat, eastern cottontail rabbits, wild turkeys, American robins, mockingbirds, Carolina wren, European starlings and lots of insects can all gobble up poison ivy with no itching at all! So why do they wreak havoc on 85% of us poor humans??
We can point the finger to urushiol oil (pronounced you-roo-shee-ol) which runs in the vascular system of these plants. When urushiol oil gets out of the plant and rubs onto our skin, it triggers our immune system (including our white blood cells) to launch an attack on our own cells. And we start to itch and blister. The response can take weeks to calm down and for the skin to heal. In some cases strong medicine like steroids are needed and, if not treated, the itching can lead to scarring.
So why do these plants make nasty urushiol in the first place? Just to be a menace to us? Nah! Turns out urushiol is the plants’ protection against its most voracious predators — the insects. After being grazed on by insects, the plant uses its gooey oil to seal up its wounds.
So next time you start itching after getting poison oak or ivy, take heart. Those plants have been enduring epic battles all their own.