To identify the leaves of Indiana trees, consult a tree database from a local nature preserve, government park service or university extension program. Look for identifying characteristics, such as the leaf's shape, size, color, the pattern from the veins, the stalk and the arrangement of the leaves on the branch.
Deciduous leaf shapes generally vary between simple, lobed and compound leaves. Simple leaves generally have a single, oblong shape and smooth edges. Lobed leaves have textured indentations along their edges. Compound leaves, such as those found on hickory or sumac trees, surround the primary leaf with smaller leaves on the same stalk. For conifer trees, look at the color of the neddles, thickness, length and bunching pattern.
In addition to leaves, look at a tree's bark, flowers, fruit and its location, such as whether it grows in a forested or prairie area or receives full or partial sun. Check leaves against the most common species found in Indiana, including sycamore, red and white oak, sumac, red and white pine, elm and maple.
Indiana universities offering online tree databases for leaf identification include Purdue, Depauw, Indiana State University and Butler. Schools from surrounding states, such as the University of Wisconsin at Stevens Point, Iowa State University and Ohio State University also offer databases.