I have a lot of poison ivy.  Fortunately I'm not allergic to it.  Maybe all those times fishing for trout barefoot when I was a kid helped desensitize me to it?  It grows pretty big, reaching a foot tall, but I have never seen it climb anything, trees or otherwise.  It sticks to the ground, at least every plant I have ever seen does, but it's vine-like root system travels a long way just under the leaf litter.  It gets clumps of tiny blossoms in the Spring, and white pea-sized berries in the Fall.  Also in the Fall, the leaves turn red and/or yellow.
Poison Ivy likes shade, growing all around under the trees, but I've never seen it climb:
		
		
	
	
		
	
Flowers in the Spring:
		
	
Berries in the Fall. The red leaf on the right side of the photo is poison ivy, the other leaves are not:
		
	
One vine that does climb trees is wild grapes:
		
	
I hate grapevines. They are such a tangled mess and sometimes make for dangerous wood cutting. They get big enough that I am able to cut a few pieces of firewood out of them, but not big enough to split them:
		
	
Another vine that climbs trees is this thing. It's leaves turn bright red in the Fall. I don't remember what it's called, but it's not poison ivy:
		
	
And then there's this thing that climbs trees. I don't know what it is, but it's not poison ivy either:
		
	
	
		
			
		
		
	
				
			Poison Ivy likes shade, growing all around under the trees, but I've never seen it climb:
Flowers in the Spring:
Berries in the Fall. The red leaf on the right side of the photo is poison ivy, the other leaves are not:
One vine that does climb trees is wild grapes:
I hate grapevines. They are such a tangled mess and sometimes make for dangerous wood cutting. They get big enough that I am able to cut a few pieces of firewood out of them, but not big enough to split them:
Another vine that climbs trees is this thing. It's leaves turn bright red in the Fall. I don't remember what it's called, but it's not poison ivy:
And then there's this thing that climbs trees. I don't know what it is, but it's not poison ivy either:
	
	
hh: