To identify a tree using an ornamental tree index, choose a subcategory within each section that most clearly describes the selected tree. Within a tree identification guide, each classification narrows down the possibilities. For instance, some indexes begin by asking the location of the tree: eastern and central states or the western United States.
After that choice, the user selects what hangs from the tree: leaves or needles. Leaf subcategories are simple, compound -- with multiple blades on one stem -- or fan-shaped. Simple leaves are then divided up into those that are directly opposite each other on a twig and those that are staggered.
The next category for opposite leaves is shape. The index user must decide if leaves are shaped more like hands, hearts or smooth blades. Flowering dogwood trees have leaves with smooth edges.
Other identification indexes ask users to focus on one specific aspect of trees, such as leaves, fruit or names. For instance, fruit identification begins with selecting an image that best matches, such as a pine cone, acorn, winged seeds or pods. Each category is broken down again, and the user makes another choice. Fruit pods might be long, triangular or square. According to one index, a tree with a long fruit pod is a Northern Catalpa.