While checking out the wild raspberries and blackberries that are growing in abundance around our area (Upper Peninsula of Michigan) I noticed what I'm really hoping is NOT poison ivy. From a distance it looks very similar to the rubus species, but then I realized it was growing on a vine. However, after some research I saw that Rubus ursinus can grow on a vine, so I'm wondering if other species of rubus grow on vines and how to tell the difference between these and poison ivy.

The vines I saw were long and trailing, light green and hairy, however the base of the plant was a woody stem with prickers on it (not root-hairs used to attach to trees). The leaves were trifoliate and opposite, not alternating. I did not see any young, reddish leaves. A few of the leaves did have the mitten appearance, though not all of them. {{gwi:1354444}} is a picture of the leaves.

So I guess three questions really: is this poison ivy? Which species of rubus grow on vines? And how can you tell the difference between them and poison ivy? Thanks