Acer saccharum, the sugar maple, is a species of flowering plant in the soapberry and lychee family Sapindaceae. It is native to the hardwood forests of eastern Canada and the eastern United States. Sugar maple is best known for being the primary source of maple syrup and for its brightly colored autumn foliage. It may also be called "rock maple," "sugar tree," "sweet maple," or, particularly in reference to the wood, "hard maple," "birds-eye maple," or "curly maple," the last two being specially figured lumber.
The leaf are deciduous, up to long and wide, palmate, with five lobes and borne in opposite pairs. The basal lobes are relatively small, while the upper lobes are larger and deeply notched. In contrast with the angular notching of the silver maple, however, the notches tend to be rounded at their interior. The fall color is often spectacular, ranging from bright yellow on some trees through orange to fluorescent red-orange on others. Sugar maples also have a tendency to color unevenly in fall. In some trees, all colors above can be seen at the same time. They also share a tendency with for certain parts of a mature tree to change color weeks ahead of or behind the remainder of the tree. The leaf buds are pointy and brown-colored. The recent year's growth twigs are green, and turn dark brown.
The are in of five to ten together, yellow-green and without ; flowering occurs in early spring after 30–55 growing degree days. The sugar maple will generally begin flowering when it is between 10 and 200 years old. The fruit is a pair of samaras (winged seeds). The seeds are globose, in diameter, the wing long. The seeds fall from the tree in autumn, where they must be exposed to 45 days of temperatures below to break their coating down. Germination of A. saccharum is slow, not taking place until the following spring when the soil has warmed and all frost danger is past. It is closely related to the black maple, which is sometimes included in this species, but sometimes separated as Acer nigrum. The bigtooth maple ( Acer grandidentatum) and Acer floridanum ( Acer floridanum) are also treated as a varieties or subspecies of northern sugar maple by some botanists.
The sugar maple can be confused with the Norway maple, which is not native to America but is commonly planted in cities and suburbs, and they are not closely related within the genus. The sugar maple is most easily identified by clear sap in the leaf petiole (the Norway maple has white sap), brown, sharp-tipped buds (the Norway maple has blunt, green or reddish-purple buds), and shaggy bark on older trees (the Norway maple bark has small grooves). Also, the leaf lobes of the sugar maple have a more triangular shape, in contrast to the squarish lobes of the Norway maple.
The minimum seed-bearing age of sugar maple is about 30 years. The tree is long-lived, typically 200 years and occasionally as much as 300.
Sugar maple is native to areas with cooler climates and requires a hard freeze each winter for proper dormancy. In northern parts of its range, January temperatures average about and July temperatures about ; in southern parts, January temperatures average about and July temperatures average almost . Seed germination also requires extremely low temperatures, the optimal being just slightly above freezing, and no other known tree species has this property. Germination of sugar maple seed in temperatures above is rare to nonexistent.
Acer saccharum is among the most shade tolerant of large deciduous trees, and very old trees in second-growth settings can grow large even in the understory for many years. Its shade tolerance is exceeded only by the striped maple, a smaller tree. Like other maples, its shade tolerance is manifested in its ability to germinate and persist under a closed canopy as an understory plant, and respond with rapid growth to the increased light formed by a gap in the canopy. Sugar maple can tolerate virtually any soil type short of pure sand, but does not tolerate xeric or swampy conditions.
Sugar maples are deeper-rooted than most maples and engage in hydraulic lift, drawing water from lower soil layers and exuding that water into upper, drier soil layers. This not only benefits the tree itself, but also many other plants growing around it.
The mushroom Pholiota squarrosoides is known to decay the logs of the tree.
Human influences have contributed to the decline of the sugar maple in many regions. Its role as a species of mature forests has led it to be replaced by more opportunistic species in areas where forests are cut over. The sugar maple also exhibits a greater susceptibility to pollution than other species of maple. Acid rain and soil acidification are some of the primary contributing factors to maple decline. Also, the increased use of salt over the last several decades on streets and roads for deicing purposes has decimated the sugar maple's role as a street tree.
In some parts of New England, particularly near urbanized areas, the sugar maple is being displaced by the Acer platanoides. The Norway maple is also highly shade tolerant, but is considerably more tolerant of urban conditions, resulting in the sugar maple's replacement in those areas. In addition, Norway maple produces much larger crops of seeds, allowing it to out-compete native species.
Additionally, the samaras (seeds) can be soaked, and—with their wings removed—boiled, seasoned, and roasted to make them edible.
Canadian maple, often referred to as "Canadian hardrock maple", is prized for , especially the shafts. Some production-line cues will use lower-quality maple wood with cosmetic issues, such as "sugar marks", which are most often light brown discolorations caused by sap in the wood. The best shaft wood has a very consistent grain, with no marks or discoloration. Sugar marks usually do not affect how the cue plays, but are not as high quality as those without it. The wood is also used in skateboards, gunstocks, and flooring for its strength. Canadian hardrock maple is also used in the manufacture of electric guitar necks due to its high torsional stability and the bright, crisp resonant tone it produces. If the grain is Curly maple, with flame or quilt patterns, it is usually reserved for more expensive instruments. In high-end guitars this wood is sometimes Torrefaction to cook out the lignin resins, allowing the greater stability to climate and environmental changes, and to enhance its tonal characteristics as the instrument's resonance is more evenly distributed across the cellulose structure of the wood without the lignin.
The sugar maple is the state tree of the US states of New York, Vermont, West Virginia, and Wisconsin.
It is depicted on the state quarter of Vermont, issued in 2001.
Urban planting
Cultivars
Use by Native Americans
Big trees
In popular culture
Further reading
External links
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