Maple trees belong to the genus Acer, which includes approximately 130 to 160 different species of trees and shrubs worldwide. The majority of maple species are native to East Asia, but they also have a strong presence across North America and Europe. Maples are valued for their use as a source for lumber and for the production of maple syrup. Many species are also highly prized in horticulture for their dramatic autumn foliage, making them a common sight in gardens and urban landscapes.
Structural Features Used for Identification
Maple trees share defining characteristics that place them within the Acer genus. One reliable feature is the arrangement of their leaves and branches, which are positioned directly opposite each other on the stem. This opposite branching pattern is uncommon among deciduous trees and serves as a quick identifier, even when leaves are absent in winter.
The leaves are typically palmate, shaped like a hand with lobes radiating from a central point. The number and depth of these lobes, along with the shape of the notches (sinuses), vary significantly and are used for species differentiation.
Another distinguishing feature is the samara, the distinctive winged fruit often called a “helicopter.” Each samara contains a single seed and is designed with a wing that aids in wind dispersal as it spins while falling. The angle at which the two wings of a paired samara meet is a consistent trait used for identification. Finally, the texture of the bark changes as the tree ages, transitioning from smooth on younger stems to fissured, ridged, or sometimes shaggy on mature trunks.
Major North American Forest Maples
The most commercially and ecologically significant maples in North America are the Sugar, Red, and Silver maples, which form a large part of the eastern forest canopy.
Sugar Maple (Acer saccharum)
The Sugar Maple is the primary source for commercially produced maple syrup, due to the high sugar concentration in its sap. Its leaves are typically five-lobed with smooth edges and rounded, U-shaped sinuses. Mature Sugar Maples develop tight, ridged, and often furrowed bark. This species is celebrated for its brilliant fall colors, which span a range from deep orange to crimson.
Red Maple (Acer rubrum)
The Red Maple is one of the most adaptable maples, capable of growing in a wide range of conditions, including wetter soils where other maples may struggle. Its leaves typically have three to five lobes with serrated edges and distinct, shallow, V-shaped sinuses. The Red Maple is often the first tree in the forest to show color, with its buds, flowers, leaf stems, and fall foliage all turning red. The bark on mature Red Maples becomes rougher with long furrows and ridges.
Silver Maple (Acer saccharinum)
The Silver Maple is characterized by its fast growth rate and its common habitat along riverbanks and floodplains. Its leaves are deeply five-lobed, cut more than halfway to the central vein, and have sharply pointed tips. The underside of the leaf is a striking silvery-white, noticeable when the leaves flutter in the wind. This species often has shaggy, flaky gray bark on older trunks and typically displays a less vibrant, pale yellow fall color. Silver Maples have a tendency toward weak wood and brittle branches, making them a less desirable choice for some urban plantings.
Specialized Ornamental and Landscape Maples
Beyond the large forest species, many maples are cultivated specifically for their ornamental value in smaller landscapes and gardens.
Japanese Maples (Acer palmatum)
Japanese Maples (Acer palmatum and related species) are prized for their small size and delicate foliage. These trees rarely exceed 25 feet and are known for their intricate, deeply dissected or lacy leaf forms. Some cultivars feature red, purple, or variegated summer foliage. They have smooth bark and often display a graceful, rounded, or weeping growth habit.
Norway Maple (Acer platanoides)
The Norway Maple is a species native to Europe that was widely planted in North American cities due to its tolerance for pollution and its dense, wide-spreading canopy. A distinguishing feature is the milky white sap that oozes out when a leaf petiole is broken from the stem. This shade tree has since become invasive in some regions, outcompeting native species.
Paperbark Maple (Acer griseum)
The Paperbark Maple is a smaller species native to central China. It is grown primarily for its striking, cinnamon-brown bark. This bark continuously peels and curls into thin, papery layers that remain on the trunk, creating visual interest, particularly during the winter months. Its leaves turn an orange-red in the fall.