Hickory

An arborist who came to evaluate some trees on our property identified this particular plant as a hickory sapling.

I had to check; no, they're not thorns. The barbs seem to be the beginnings of new branches.

Are those thorns?

Good point. I added another photo, but as I said, it's a young plant, so I'm not sure if there's anything to be gained by looking at the bark. But the second photo does show how the leaves tend to grow. It's kind of impressive, how quickly it's grown; I'd say it's about nine or ten feet tall, and it only sprouted this spring, I believe.

It is very difficult to identify a plant from a single leaf, especially when the shape is one shared by many species. Take a picture of the entire plant or take note of the characteristics and list them.