Leafsnap is a free app for the Iphone (Ipad App coming soon) which was developed by researchers from Columbia University, the University of Maryland and Smithsonian Institute.
It is the first in a series of electronic field guides which uses visual recognition software to help identify tree species from photographs of their leaves. Using your camera, you can take a picture of the leaf and then identify it if it is in the database. The app includes high resolution photos to help you determine the species of tree you are looking at.
The app currently includes the trees of New York and Washington, D.C, but soon will include all the trees of the continental US.
LeafSnap can help turn anyone into a scientist and would be an amazing tool when taking students out into the field. With just your Iphone, you will be able to snap photos of leaves and not only identify them, but get detailed information.