[header] How to identify trees by leaves [title] Determine the leaf type. [step] The most common leaf type is a broadleaf, which is wide and flat. But leaves also come in needle, cactus, and scale types. 
Needle leaves are long and pointed like a pin, cactus leaves are thick and usually covered in spines, and scales leaves are thin, oblong leaves that primarily belong to cypress trees. Compare your leaf to the different basic leaf types to narrow down what species your leaf might be.