Is this poison ivy? Sometimes it’s tough to tell. Take the quiz.

Which plant in this group of green leaves is poison ivy?

The website has a fun quiz to help you figure it out. Turns out there are two types of poison ivy and they both grow around the Chesapeake Bay. Generally, Western poison ivy — a ground vine only — grows mainly in the northern Bay. Eastern poison ivy — a ground AND climbing vine — grows around most of the Chesapeake Bay.

poison ivy map
Orange is the Western poison ivy growing area. Green is where Eastern poison ivy grows. They overlap on the top of the Chesapeake Bay. (Courtesy

Then, you have to deal with all the quirky ways poison ivy grows. There’s a lot of variation in how the leaves look. Here’s what says:

  • Poison ivy NEVER HAS thorns of any kind.
  • Poison ivy ALWAYS HAS leaves (or leaflets) of three, NEVER more.
  • Poison ivy NEVER has fine, saw-tooth leaf edges, or scalloped edges.
  • Poison ivy SOMETIMES has notches, so notches really don’t help us.
  • Poison ivy SOMETIMES is shiny, so shiny really doesn’t help us.
Odd poison ivy
This one is a ‘poser’. It has round leaves, but says it is, indeed, the real stuff.

“Leaves of three, let them be,” according to the Poison Ivy Information Center,  The center estimates about 90% of the population is allergic to it, and people who claim to be ‘not’ allergic can develop sensitivity at any time. “It’s a matter of time and exposure.”

The allergic itch is caused by the plant’s urushiol oil, and it’s potent stuff.

  • Only 1 nanogram (billionth of a gram) needed to cause rash
  • Average is 100 nanograms for most people
  • 1/4 ounce of urushiol is all that is needed to cause a rash in every person on earth
  • 500 people could itch from the amount covering the head of a pin
  • Specimens of urushiol several centuries old have found to cause dermatitis in sensitive people.
  • 1 to 5 years is normal for urushiol oil to stay active on any surface including dead plants
  • Derived from urushi, Japanese name for lacquer

Both websites have excellent tips on how to avoid an outbreak if you think you’ve been exposed and how to deal with it once a rash breaks out.


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