These leaf samples are from a very large tree in Palouse Falls State Park in eastern Washington state. There are several of these trees scattered throughout the visitors parking and camping areas there. The leaves are reminiscent of maple or sycamore, but thick and glossy. And I've never encountered leaves with furry white backs! Can you identify this species?
This must be Populus alba. Are you on a Geology field trip? Incredible area for geological history!
The shape of the leaf is very common but that white stuff is very distinctive. Thick heavy white furry stuff on the underside of the leaf and petiole is called tomentose. Add to that, the White Poplar has unusually thick heavy duty dark green leaves and you get a heavy duty tree that is able to handle the temperature changes and high winds found in the high deserts.
They are found along rivers and in the bottom of draws between ridges to ensure a steady source of water. Smart tree.
I think its Populus alba, common name White Poplar. The bark on these has markings which are quite distinctive too, though the colour varies depending on its age, see here http://treesplanet.blogspot.com/2014/01/populus-alba-white-poplar-abele.html#.W5LqY6DTUn4
