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''Acer rubrum'' (Red Maple, also known as Swamp, Water or Soft Maple), is one of the most common and widespread deciduous trees of eastern and central North America. The U.S. Forest service recognizes it as the most common species of tree in America. The red maple ranges from southeastern Manitoba around the Lake of the Woods on the border with Ontario and Minnesota, east to Newfoundland, south to Florida, and southwest to eastern Texas. Many of its features, especially its leaves, are quite variable in form. At maturity it often attains a height of around . It is aptly named as its flowers, petioles, twigs and seeds are all red to varying degrees. Among these features, however, it is best known for its brilliant deep scarlet foliage in autumn. Over most of its range, red maple is adaptable to a very wide range of site conditions, perhaps more so than any other tree in eastern North America. It can be found growing in swamps, on poor dry soils, and most anywhere in between. It grows well from sea level to about . Due to its attractive fall foliage and pleasing form, it is often used as a shade tree for landscapes. It is used commercially on a small scale for maple syrup production as well as for its medium to high quality lumber. It is also the State Tree of Rhode Island. The red maple can be considered weedy or invasive.〔(【引用サイトリンク】url=http://plants.usda.gov/core/profile?symbol=ACRU )〕 It is taking over forests in the eastern US, replacing traditional mainstays like oaks, as well as hickories and pines.〔(【引用サイトリンク】url=http://www.nytimes.com/1999/04/27/science/eastern-forests-change-color-as-red-maples-proliferate.html )〕 ==Description== Though ''A. rubrum'' is usually easy to identify, it is highly changeable in morphological characteristics. It is a medium to large sized tree, reaching heights of and exceptionally over . The leaves are usually long on a full grown tree. The trunk diameter can range from , depending on the growing conditions. Its spread is about . A 10-year-old sapling will stand about tall. In forests, the bark will remain free of branches until some distance up the tree. Individuals grown in the open are shorter and thicker with a more rounded crown. Generally speaking, however, the crown is irregularly ovoid with ascending whip-like curved shoots. The bark is a pale grey and smooth when the individual is young. As the tree grows the bark becomes darker and cracks into slightly raised long plates.〔 The largest known living red maple is located near Armada, Michigan, at a height of and a bole circumference, at breast height, of .〔 The leaves of the red maple offer the easiest way to distinguish it from its relatives. As with nearly all North American maple trees, they are deciduous and arranged oppositely on the twig. They are typically long and wide with 3-5 palmate lobes with a serrated margin. The sinuses are typically narrow, but the leaves can exhibit considerable variation.〔 When 5 lobes are present, the three at the terminal end are larger than the other two near the base. In contrast, the leaves of the related silver maple, ''A. saccharinum'', are much more deeply lobed, more sharply toothed and characteristically have 5 lobes. The upper side of ''A. rubrums leaf is light green and the underside is whitish and can be either glaucous or hairy. The leaf stalks are usually red and are up to long. Furthermore, the leaves can turn a brilliant red in autumn, but can also become yellow or orange on some individuals. The twigs of the red maple are reddish in color and somewhat shiny with small lenticels. Dwarf shoots are present on many branches. The buds are usually blunt and greenish to reddish in color, generally with several loose scales. The lateral buds are slightly stalked, and in addition there may be collateral buds present as well. The buds form in fall and winter and are often visible from a distance due to their reddish tint. The leaf scars on the twig are V-shaped and contain 3 bundle scars.〔 The flowers are generally unisexual, with male and female flowers appearing in separate sessile clusters, though they are sometimes also bisexual. They appear in spring from April to May (though as early as late January in the southern part of its range), usually coming before the leaves. The tree itself is considered Polygamodioecious, meaning some individuals are male, some female, and some monoecious.〔 The red maple will begin blooming when it is about 8 years old, but it significantly varies between tree to tree: some trees may begin flowering when they are 4 years old. The flowers are red with 5 small petals and a 5-lobed calyx borne in hanging clusters, usually at the twig tips. They are lineal to oblong in shape and are pubescent. The pistillate flowers have one pistil formed from two fused carpels with a glabrous superior ovary and two long styles that protrude beyond the perianth. The staminate flowers contain between 4 and 12 stamens, often with 8. The fruit is a 15 to 25 millimeter (.5 to .75 inch) long double samara with somewhat divergent wings at an angle of 50 to 60 degrees. They are borne on long slender stems and are variable in color from light brown to reddish.〔 They ripen from April through early June, before even the leaf development is altogether complete. After they reach maturity, the seeds are dispersed for a 1 to 2 week period from April through July.〔 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 rubrum」の詳細全文を読む スポンサード リンク
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