My previous poison ivy post generated a surprising number of responses, some with stories regarding their own painful encounters with this plant. My naturalist friend Tim Corcoran wrote a detailed analysis of my photographs and determined with 90% certainty that they were poison ivy. Of course, I would expect nothing less from him.
His response is very educational and is quoted below:
Ahh, everyone's favorite, Poison Ivy! From a naturalist's perspective, poison ivy is such an amazing plant, especially because it is such a trickster. It takes MANY different forms, from season to season, plant to plant, and even on the same plant!. It is somewhat difficult to make a conclusive determination based on these pictures alone. Ideally, I could see this in person.
Here is what I see from your pictures:
1) Compound leaves with 3 leaflets. This means that one leaf is comprised of three leaflets. One way this is apparent is that the leaflets have little to no stems, and that the base of the leaflet stems is no thicker than the rest of the leaflet stem. This is important because a compound leaf will separate from the plant in one point only, at the base of the actual leaf stem which I can see from your first picture is wider than the rest of the stem. So it has compound leaves with 3 leaflets. This is a point towards it being poison ivy.2) Leaflets have a single tooth (first & third picture) and slight lobes/teeth (also first & third picture). Another point towards poison ivy.3) Leaflets are red - point towards poison ivy.4) Dense flower clusters at leaf base - another point towards poison ivy.5) Berries are whitish/greenish, with subtle radial depressed lines going around the whole berry (like a pumpkin) - another point towards poison ivy.6) New growth and berries coming off of a woody stem with alternating leaf scars - another point towards poison ivy.Additionally, I don't see anything indicating that it is not poison ivy. All that said, I'd say with about 90% certainty that this is poison ivy. I'd need to see it in person to say with 100% certainty. I love how excited everyone always gets about poison ivy. The plant has so many gifts. be sure to read our perspective on "Poison Ivy as Medicine" at the end of our article here:
Dissatisfied with a 90% rating, I decided to go back for a better look, and I was quite surprised to see that the plants were much more abundant than I previously noticed. The plants were literally growing from between the rocks in a basalt rock slide. In fact, it was actually quite difficult to take a step without stepping on one.
This specimen shows a variety of leaf styles on one plant. No wonder so many people are confused by poison ivy. I'm not quite the expert like Tim, but I'm going to call this at higher than 90%.