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''Not to be confused with the European species Quercus robur''. ''Quercus rubra'', commonly called northern red oak or champion oak, (syn. ''Quercus borealis''), is an oak in the red oak group (''Quercus'' section ''Lobatae''). It is a native of North America, in the eastern and central United States and southeast and south-central Canada. It grows from the north end of the Great Lakes, east to Nova Scotia, south as far as Georgia, Alabama, and Louisiana, and west to Oklahoma, Kansas, Nebraska, and Minnesota.〔(Biota of North America Program 2014 county distribution map )〕 and It prefers good soil that is slightly acidic. Often simply called "red oak", northern red oak is formally so named to distinguish it from southern red oak (''Q. falcata''), also known as the Spanish oak. It is also the state tree of New Jersey and the provincial tree of Prince Edward Island. ==Description== In many forests, this deciduous tree grows straight and tall, to , exceptionally to tall, with a trunk of up to diameter. Open-grown trees do not get as tall, but can develop a stouter trunk, up to in diameter. It has stout branches growing at right angles to the stem, forming a narrow round-topped head. It grows rapidly and is tolerant of many soils and varied situations, although it prefers the glacial drift and well-drained borders of streams. It is frequently a part of the canopy in an oak-heath forest, but generally not as important as some other oaks.〔(''The Natural Communities of Virginia Classification of Ecological Community Groups'' (Version 2.3), Virginia Department of Conservation and Recreation, 2010 )〕〔Schafale, M. P. and A. S. Weakley. 1990. ''Classification of the natural communities of North Carolina: third approximation''. North Carolina Natural Heritage Program, North Carolina Division of Parks and Recreation.〕〔 Under optimal conditions, northern red oak is fast growing and a 10-year-old tree can be tall.〔(Arbor Day Foundation, Northern Red Oak )〕 Trees may live up to 500 years according to the USDA,〔(United States Department of Agriculture Plant Guide )〕 and a living example of 326 years was noted in 2001 by Orwig et al.〔(Lamont-Doherty Earth Observatory and Columbia University, Eastern US oldlist )〕〔 Northern red oak is easy to recognize by its bark, which feature bark ridges that appear to have shiny stripes down the center. A few other oaks have bark with this kind of appearance in the upper tree, but the northern red oak is the only tree with the striping all the way down the trunk.〔 * Bark:Dark reddish grey brown, with broad, thin, rounded ridges, scaly. On young trees and large stems, smooth and light gray. Rich in tannic acid. Branchlets slender, at first bright green, shining, then dark red, finally dark brown. Bark is brownish gray, becoming dark brown on old trees. * Wood: Pale reddish brown, sapwood darker, heavy, hard, strong, coarse-grained. Cracks in drying, but when carefully treated could be successfully used for furniture. Also used in construction and for interior finish of houses. Sp. gr., 0.6621; weight of cu. ft., 41.25 lbs. * Winter buds: Dark chestnut brown (reddish brown), ovate, acute, generally 6 mm long〔 * Leaves: Alternate, seven to nine-lobed, oblong-ovate to oblong, five to ten inches long, four to six inches broad; seven to eleven lobes tapering gradually from broad bases, acute, and usually repandly dentate and terminating with long bristle-pointed teeth; the second pair of lobes from apex are largest; midrib and primary veins conspicuous. Lobes are less deeply cut than most other oaks of the red oak group (except for black oak which can be similar). Leaves emerge from the bud convolute, pink, covered with soft silky down above, coated with thick white tomentum below. When full grown are dark green and smooth, sometimes shining above, yellow green, smooth or hairy on the axils of the veins below. In autumn they turn a rich red, sometimes brown. Often the petiole and midvein are a rich red color in midsummer and early autumn, though this is not true of all red oaks. The acorns mature in about 18 months after pollination; solitary or in pairs, sessile or stalked; nut oblong-ovoid with broad flat base, full, with acute apex, one half to one and one-fourth of an inch long, first green, maturing nut-brown; cup, saucer-shaped and shallow, wide, usually covering only the base, sometimes one-fourth of the nut, thick, shallow, reddish brown, somewhat downy within, covered with thin imbricated reddish brown scales. Its kernel is white and very bitter.〔 Despite this bitterness, they are eaten by deer, squirrels and birds.〔 Red oak acorns, unlike the white oak group, display epigeal dormancy and will not germinate without a minimum of three months' exposure to sub- temperatures. They also take two years of growing on the tree before development is completed.〔(Flora of North America: ''Quercus rubra'' )〕 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「Quercus rubra」の詳細全文を読む スポンサード リンク
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