Maple Tree Identification
The commercial production of maple products in North America occurs primarily in the northeastern United States and southeastern Canada. This is the geographic area of greatest abundance of sugar maple (Acer saccharum) and black maple (Acer nigrum), the two most preferred and most commonly tapped maple species.
There are thirteen native maple species in North America. While most of these species are probably tapped to some extent, at least by hobbyists, sugar and black maple, along with red maple (Acer rubrum), provide most of the commercial sap. A fourth maple species, silver maple (Acer saccharinum), is sometimes tapped, particularly in roadside operations, and is often confused with red maple.
Table contains a descriptive comparison and Figures through illustrate characteristic leaves, bark, twigs, and fruits of sugar, black, red and silver maple. These four species share several characteristics in common. All have leaves of similar shape: a single leaf blade with the characteristic maple shape, lobes radiating out like fingers from the palm of a hand (palmately lobed) with notches (called sinuses) between the lobes. Like all maples, the leaves, buds and twigs of all four are attached in pairs opposite each other along the branches. Also, all four produce a fruit called a samara (or double samara), which is a pair of connected, winged seeds.
Species Suitable for Maple Product Production
Sugar and Black Maple
Sugar and black maple are very similar species and unquestionably the most preferred species for producing maple products, primarily because of their high sugar content. Sugar maple occurs naturally throughout most of the northeastern United States and southeastern Canada. Black maple, on the other hand, occupies a much smaller natural range. Distinguishing between them may be more of an academic exercise than one useful in sugarbush management because they are essentially identical in quality as sugartrees, and they often hybridize producing trees with a range of characteristics, making it difficult to clearly distinguish between them.
Identifying a tree as a sugar or black maple is easily done from the leaves by observing lobed leaves, the paired opposite attachment of the leaves along the stem and the lack of teeth along the leaf margin; from the bark of older trees by observing the long plates that remain attached on one side; from the twigs by observing the opposite arrangement of buds and the relatively long, pointed, brownish terminal bud; and from the seed by observing its horseshoe shape and size. Distinguishing between sugar and black maple is best done by comparing the leaf structure (particularly the number of lobes, droopiness and presence or absence of stipules along base of petiole) and by the degree of bumpiness of the twigs.
Sugar and black maples are found on a variety of soils and site conditions, but neither tolerates excessively wet or dry sites, and both grow best on moist, deep, well-drained soils. Black maple is more likely to be found along moist river bottoms. Both species can be found growing in pure stands, with each other, or with a wide variety of other hardwood species including American beech, American basswood, yellow birch, black cherry, northern red oak, yellow poplar and black walnut. Both species have been planted extensively as roadside trees which are often tapped as part of a sugaring operation. Plantations of sugar maple have also been established with the intent of developing efficient, productive sugarbushes. Both species are relatively long lived, capable of living well beyond 200 years, with trunk diameters greater than 30 inches and heights greater than 100 feet.
Sugar and black maple both grow in the shade of other trees (they are shade tolerant), and trees of many different ages (sizes) are often found in a forest. Both species are also found in stands composed of trees that are essentially all the same age (size). Healthy sugar and black maple trees growing in overstocked uneven-aged or even-aged stands can be expected to achieve tapable size in 40 to 60 years, depending on overall site quality. Thinning or release cutting dramatically reduces this age-to-tapable-size.