Over 100 species of maple, genus Acer, exist throughout the world. About 14 of those are native to the United States. Sugar, red and silver maples are valued for their beauty but also for their sap, which can be rendered into maple syrup. At a 2 percent average sugar content, sugar maples have the highest concentration of sugar for producing syrup. Nearly twice as much sap from other species is required to produce the same amount of maple syrup. Maples are similar in appearance, but a few characteristics set sugar maples apart.
Examine the leaves on the tree, or those that have fallen below the tree. Sugar maple leaves are 3 to 5 inches long, are broad at the base and have five lobes. Notches between the lobes are rounded and the leaves have a slight wavy tooth pattern on the edges. The tops of sugar maple leaves are dark green, and the undersides are a paler shade of green. By contrast, both red and silver maple leaves are a paler green on top with whitish to silvery-white undersides. Silver maple leaves have three to five lobes with long points and noticeably toothy edges. Red maples have three broad lobes.
Look up at the branches to see if the tree has fruit, called samara. This fruit has a large seed with one or two wings to help the seed float to the ground. Sugar, red and silver maples all have two-winged samara, but the silver maple's fruit matures in fall while the others do so in spring.
Determine if the maple tree has flowers in spring. Sugar maple flowers are nearly invisible, while red maples bear prominent red clusters and silver maples show greenish-yellow flowers.
Touch and study the bark. Young maple trees of each variety have light gray to brownish bark, smooth in appearance. Mature trees begin to differ, with sugar maples developing irregular plates of bark that often split away vertically. Silver maples develop a deeply furrowed bark that pulls loose in flakes. Red maples have a tighter bark, smooth and gray on stems, rough and brown on trunks of mature trees.
Estimate the size of the tree. Sugar maples grow taller than their cousins, often to heights of 60 to 100 feet with trunks that can exceed 3 feet in diameter. Silver and red maples are 40 to 60 feet tall. Red maple trunks are typically 1 to 2 feet in diameter, while silver maples have trunks closer to the size of sugar maples -- 3 to 4 feet in diameter.
Observe the tree in autumn when fall colors are bright. Sugar maples display bright yellows, oranges and crimson hues. Red maples show a fiery red color. Silver maples turn yellow, sometimes orange or red, but the leaves brown before they fall from the tree.