About 3 months ago I stumbled upon an unusual ash tree while hiking along a creek in Salt Lake City Utah. It looks like no other ash I've encountered before. Its leaves are semi-rounded with lobes, light green leaves, the seeds are smaller than green ash, and leafs out way late. The location was right at the edge of the riparian forest which is very dry, not next to the streambed. It was growing next to some Utah junipers, tree of heaven, honey locusts, black locusts, Gambel oak, Norway maple, narrowleaf ash, and green ash. The closest native ash is Fraxinus anomala (Single-leaf ash), and even then it's not native to northern Utah. Still amazing how these trees survive in less than 13 inches of precipitation. I'm assuming it's either a rare mutation, a hybrid, or it's an isolated native species. I did collect some seeds of the tree so now they're in stratification and hopefully they'll germinate next spring. Any help identifying is appreciated.
http://imgur.com/a/pSCQV