I've two trees growing behind my fence in Oklahoma. I've never seen them before and cannot for the life of me identify them. They are about 40 feet tall and very skinny. The trunk is maybe 7-9 inches in diameter. There are about three or so small limbs branching out from the body of the tree. Most of the leaves branch out at the top. It kind of looks like a mop. Any help would be appreciated. It is driving me nuts trying to identify it. Thanks.