giant weed growing with tree?

We have a tree in our back yard in central Ohio that has either a weed or another tree variety growing alongside it. I assume it is a weed, but want to make sure I know what it is before I try to remove it. The "trunk" is thin and grows out of the ground less than a half inch from the other tree's trunk. It does not grow straight up, it has slender branches, and is currently close to 6 feet high. The leaves are about 6 inches long. Any ideas?

 

That looks like a white oak tree leaf to me.

 

Thank you for your responses. How strange for it to grow alongside another tree like that. Neither tree is doing all that well. The ash it's next to was ignored and then trimmed improperly. Should we see acorns from the oak? I don't think we ever have.

 

When it gets mature, it will make acorns. The ash tree will probably die soon anyway, from EAB.

 

Most oaks take 50 years before making acorns. Some species make take only 20.