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''Acer saccharum'' Marsh. (sugar maple or rock maple) is a species of maple native to the hardwood forests of eastern Canada, from Nova Scotia west through Quebec and southern Ontario to southeastern Manitoba around Lake of the Woods, and the eastern United States, from Minnesota to Georgia and Texas.〔Germplasm Resources Information Network: (''Acer saccharum'' )〕 Sugar maple is best known for its bright fall foliage and for being the primary source of maple syrup. ==Description== ''Acer saccharum'' is a deciduous tree normally reaching heights of tall,〔Northern Ontario Plant Database: (''Acer saccharum'' )〕〔Oklahoma Biological Survey: (''Acer saccharum'' )〕 and exceptionally up to . A 10-year-old tree is typically about tall. When healthy, the Sugar Maple can live for over 400 years. The leaves are deciduous, up to long and equally wide,〔 with five palmate lobes. 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 through orange to fluorescent red-orange, although they look best in the northern part of its range. 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 red maples 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 flowers are in panicles of five to 10 together, yellow-green and without petals; flowering occurs in early spring after 30–55 growing degree days. The sugar maple will generally begin flowering when it is between 10 to 15 years old. The fruit is a double samara with two 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 90 days of temperatures below -18 °C 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 western American bigtooth maple (''Acer grandidentatum'') is also treated as a variety or subspecies of sugar maple by some botanists. The sugar maple is also often confused with the Norway maple, though 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. Although many people think a red sugar maple leaf is featured on the flag of Canada, the official maple leaf does not belong to any particular maple species; although it perhaps most closely resembles a sugar maple leaf of all the maple species in Canada, the leaf on the flag was specially designed to be as identifiable as possible on a flag waving in the wind without regard to whether it resembled a particular species' foliage.〔http://www.canadianheritage.gc.ca/progs/cpsc-ccsp/sc-cs/df1_e.cfm〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Acer saccharum」の詳細全文を読む スポンサード リンク
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