Review the Basics of tree ID - ID tools slideshow (or pdf)
Figure out your unknown by clicking on the button that best describes it. A table will list the possible matches, with links to our tree fact sheets. If a picture exactly matches your leaf, clicking on the picture will take you directly to a fact sheet for that species.
An interview - Think of this as a process of elimination, narrowing the possibilities with each selection. If you select "I don't know" for every decision, you will view all the species in the database. Only make selections that you are sure about - or you might accidently eliminate the answer!