Tree identification

What's the easiest way to identify a tree? A dichotomous key of course. A dichotomous key is a tool that allows anyone to determine the identity of items in the natural world such as wildflowers, mammals, reptiles, rocks, fish, and trees. Dichotomous means "dividing into two parts" so the dichotomous keys below will always give only two choices for each step until you have identified the tree.

Dichotomous tree keys

Tree and plant identification guides

Forest Trees of Wisconsin: How to Know Them [PDF] - A paper copy of the guide is also available for order on Education Connection [PDF].
Wisconsin Urban Tree Key – A guide to the most common urban trees in Wisconsin.
What Tree is That? [exit DNR] – A tree identification guide developed by the Arbor Day Foundation.

Smartphone apps

Leafsnap [exit DNR] is an electronic field guide developed by researchers from Columbia University, University of Maryland, and the Smithsonian Institution. This free mobile app uses visual recognition software to help identify tree species from photographs of their leaves.