To identify a tree's species, look for its leaf, fruit, cone or needle in a tree species guide, such as the one at Arborday.org. When leaves are shed during the winter, examine other parts of the tree, such as twigs and branch patterns.
Trees with leaves, also called hardwoods, have either simple or compound leaves. A simple leaf has one blade attached to a stalk and is either lobed or unlobed. A lobed leaf has projections around its edge, while an unlobed leaf does not. Compound leaves are composed of secondary leaves, or leaflets, that are attached to a small stalk. Hardwood trees are deciduous, which means they shed their leaves in winter. Some of the most common North American hardwood trees are the green ash, yellow birch and boxelder maple.
North American trees that have needles instead of leaves, also called evergreens, belong to either the fir, cypress, spruce, pine or larch family. Trees with clusters of needles are either pines or larches, while trees with single needles are either spruce, fir, cypress or hemlocks.
Trees with scale-like leaves belong to the cedar or juniper families. Evergreens usually retain their needles or scaly leaves during the winter with some exceptions, such as baldcypress and tamaracks. Some evergreens that retain their needles are Douglas firs and Port Orford cedars.