The "National Audubon Field Guide to Trees" states that there are nearly 125 species of maple trees and shrubs growing across the planet. Of these, 13 species are native to North America, with others introduced as ornamentals. The maples share certain traits, such as having their seeds develop in a specific way and possessing leaves that grow opposite each other in pairs along the branches. Identifying maples involves taking the time and effort to carefully study the different parts of the tree, looking for what sets each species apart from the others.
Evaluate the size difference from one maple species to the next. Some maples will grow only as tall as shrubs or a small tree, like the mountain maple of the Northeast, while others attain heights as tall as 100 feet, such as the bigleaf maple of the Pacific Coast.
Count the number of lobes on a maple leaf. All maple species in the United States, with the exception of a tree called boxelder, have simple lobed leaves, but the number of lobes vary between species. Some have three to five lobes, like the sugar maple, while others have only three lobes, which is the case with black maple. Others have many lobes, like the seven to nine on a vine maple leaf.
Measure the width and the length of maple leaves. Size matters greatly when looking to identify maple trees via their leaves. Some species have much larger leaves than others do. The Florida maple's 3-inch wide leaves are much smaller next to those of the red maple, which has leaves as wide and long as 6 inches. Bigleaf maple leaves make other maple leaves appear tiny; they have foot-wide leaves.
Look at the colors of the maple leaves in summer and in fall. Certain species have leaves that typically are different shades of green before turning to a specific color or colors. The Vine maple, for example, has green leaves tinted with red that go to all scarlet in autumn. The Silver maple's leaves are dark green above and silvery on the lower surface, and turn to a combination of green, brown and yellow when the weather turns colder.
Examine the shape of the maple tree and considering where it is growing. A case in point is the sugar maple, a tree that, when growing by itself in an open area, will normally have a short trunk and a canopy of many spreading branches. However, sugar maples growing in a crowded forest develop differently, possessing long, tall trunks with most of the branches near the upper half of the tree.
Observe other features of a maple that can clue you in to its identity. Scan the bark of the tree, looking for color and texture. The Black maple's bark is furrowed and has a dark gray to black hue. The Red maple has red buds in winter, red stems on its leaves, and its foliage usually turns brilliant red in fall. The seeds of all maples come in joined pairs, looking like a set of wings. Those of boxelder, though, differ from other maples, having more of a V-shape to them as they hang from the tree before falling to the ground.