There are a number of people who have no clue what poison ivy looks like. "Leaves of three leave it be." seems to be the rule of thumb, but even so, some people wouldn't be able to tell it from jewelweed (the plant whose juices cure poison ivy).
There used to be poison ivy growing up the front wall of a building where I worked. It was very healthy poison ivy, and when I was running mail courier, I always managed to step around it as it overhang part of the sidewalk. One day, I was delivering the mail and I saw two of the grounds workers clearing out the vines. Both in short sleeves, the one was ripping it out with his bare hands, and passing it into the arms of the other who was carting it over to a big pile to be relocated.
"You know that's poison ivy," I said, concerned.
"No, it's not."
"Yes it is. If you are allergic, go home and take a cold shower and soap yourself off. Don't use hot water, as that will open your pores and help the oils soak in. You'll probably still break out, but it wont be as bad."
They argued and I went on to deliver the mail. When I came back, they were gone, and they had left the pile of debris, and the rest of the growing poison ivy. I imagine they both were covered, neck, arms, and face. Heaven help them if they went to the bathroom without washing their hands first.
The worst case I ever had was when I crawled through it, noticed it, and later forgot to wash down in the jewelweed solution when I got back to camp. Then I sat through a sweat lodge and probably gave it to the people sitting next to me. I created the below tutorial to help you identify it in various stages, and to tell you what things you can do if you manage to touch it, or if you break out in an itchy poison ivy rash.
Treatment - Doctors
Treatment - Over the Counter Products
Treatment - Home Remedies
Urushiol Resin and Clothes
Benefits of Poison Ivy
All the pictures in this tutorial and the following quiz were taken by me (and I didn't even catch poison ivy!).
A classic picture of poison ivy. - This is early fall and the leaves are starting to turn colors, but you can see the three leaf configuration clearly as well as the general shape of the leaf. Note that this picture does not have slightly lobed leaves. Some poison ivy does have mild lobes along the leaf edge. You can also see where the stem has been broken and has a black tint to it by the brown leaf. In the background, there's some baby oak trees.
Healthy poison ivy on a tree. - This is some rather old poison ivy as you can tell from the size of the large hairy-looking vines climbing up the tree. Grandfather poison ivy.
Closer look at poison ivy on a tree. - Notice the very large hairy-looking brown vine growing up the left side of the tree. It's trying to hide, but it's a good indication that the three-leaved plant in the front is poison ivy. I would also suspect some of the smaller vines just behind the leaves are poison ivy, though I wouldn't stick my nose in it to get close enough to see the hairy roots. See the slight lobes on the leaves here.
Bright red fall foliage. - These are the typical bright red leaves the identification guides say you can not miss. It took me a while to find some that were red to photograph, as it seems that the first stage is more yellow/orange, moving to red edges, then to full red. Black patches can be seen on the larger leaf in the lower left corner. Roots on the vine in the upper left corner are also indicators that this is poison ivy.
More fall foliage. - Here's some leaves that haven't turned completely red yet. There are black patches on the leaves.
Winter berries. - It took me a while to spot the winter berries. Mainly because I was looking just a touch too early in the season. This is growing on a mostly horizontal branch shooting out from the poison ivy vine on a tree, as I have seen other sets of berries. I've not spotted any berries for the ground cover specimen of poison ivy.
More winter berries. - This one is a bit harder to make out as the camera focused behind the berries a little.
New growth in spring. - These are almost hidden against the brown hairy growth. Unfortunately, not all new leaves will have the tell-tale hairy vines right next to it, so look closely at the tiny leaves. They do have the classic three leaf configuration.
More spring growth. - This shot shows how tiny the leaves can be. See the ones in the lower left corner of the picture; they almost look like a single leaf as they are still so tightly bundled together.
Gruesome infection pictures. - What it can look like when you get poison ivy.
http://www.10thingstoknow.biz - See one of my pictures and lots of other ones (including some rash photos) in a booklet you can buy and carry with you for reference. This link leaves my site.
http://xkcd.com/443/ - XKCD poison ivy comic. This link leaves my site.
This is an easy self-check to see if you should be able to walk into the woods and notice poison ivy. It's not difficult at all, and there's no score.
Picture Question 1.
Picture Question 2.
Picture Question 3.
Picture Question 4.
Picture Question 5.
Picture Question 6.
Fact Question 1.
Fact Question 2.
Fact Question 3.
Fact Question 4.
Fact Question 5.