Smithsonian Trees of North America has just been published. This 800 page tome is an incredibly thorough guide to just about every tree you are likely to come across as you walk about in the United States and Canada. The guide’s author, Smithsonian botanist W. John Kress, is also the cofounder of the Leafsnap app, a free mobile app that helps identify tree species from photographs of their leaves. Click here to read more about this guide from the website Smithsonian Magazine.