Oh there are tree nerds. Just as there are Dr. Who nerds and Battlestar Galactica nerds and Commodore 64 nerds, there are tree nerds. And now they have an app. It's called Leafsnap. Leafsnap debuted in April but will have a much larger database ramping up over the summer. You're out in nature, see a tree, take a picture of the leaf and hit send. That picture is cross referenced against a database at the Smithsonian, which then returns information to you about what tree it is as well as more information than you would ever need about the tree. It's like Shazam but for trees.