What kind of tree is that? Well, if you have Leafsnap, you’ll be able to answer that question. This “electronic field guide” was developed by researchers from Columbia University, the University of Maryland and the Smithsonian Institution. They have created a digital photo library which includes trees in the Northeast, New York and Washington DC (it will eventually include all of North America). Just take a picture of a leaf (place it against a white background) and by using visual recognition software, it will compare it to this digital photo library and provide you with suggestions for the most likely tree species. Available for iPhone or iPad.