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''Celtis occidentalis'', commonly known as the Common hackberry, is a large deciduous tree native to North America. It is also known as the nettletree, sugarberry, beaverwood, northern hackberry, and American hackberry.〔("Celtis occidentalis L. Hackberry ) USDA Forest Service Silvics Manual〕 It is a moderately long-lived〔 hardwood〔 with a light-colored wood, yellowish gray to light brown with yellow streaks.〔("Hackberry" ) Clary Wood Products Gallery〕 The common hackberry is easily distinguished from elms and ''some'' other hackberries by its cork-like bark with wart-like protuberances. The remarkable bark pattern is even more pronounced in younger trees, with the irregularly-spaced ridges resembling long geologic palisades of sedimentary () rock formations when viewed edge-wise (). Coins as large as USA quarters can easily be laid flat against the valleys, which may be as deep as an adult human finger. The leaves are distinctly asymmetrical and coarse-textured. It produces small berries that turn orange-red to dark purple in the autumn, often staying on the trees for several months. The common hackberry is easily confused with the sugarberry (''Celtis laevigata'') and is most easily distinguished by range and habitat. The common hackberry also has wider leaves that are coarser above than the sugarberry. ==Description== Usually the common hackberry forms a medium-sized tree, thirty to fifty feet in height,〔 with a slender trunk; however, it can rise to the height of one hundred and thirty feet, in the best conditions in the southern Mississippi valley area. In the middle states of its range it seldom attains a height of more than sixty feet, and has a handsome round-topped head and pendulous branches. It prefers rich moist soil, but will grow on gravelly or rocky hillsides. The roots are fibrous and it grows rapidly. In the western part of its range with less rainfall and poorer soils it normally averages about thirty feet in height, but at least one specimen was found at ninety five feet.〔 The maximum age attained by hackberry is probably between 150 and 200 years in ideal conditions.〔 The bark is light brown or silvery gray, broken on the surface into thick appressed scales and sometimes roughened with excrescenses; pattern is very distinctive. The branchlets are slender, light green at first, finally red brown, at length become dark brown tinged with red. The winter buds are axillary, ovate, acute, somewhat flattened, one-fourth of an inch long, light brown. Scales enlarge with the growing shoot, the innermost becoming stipules. No terminal bud is formed. The leaves are alternately arranged on stems, ovate to ovate-lanceolate, more or less falcate, two and a half to four inches (102 mm) long, one to two inches wide, very oblique at the base, serrate, except at the base which is mostly entire, acute. Three-nerved, midrib and primary veins prominent. They come out of the bud conduplicate with slightly involute margins, pale yellow green, downy; when full grown are thin, bright green, rough above, paler green beneath. In autumn they turn to a light yellow. Petioles slender, slightly grooved, hairy. Stipules varying in form, caducous. The flowers appear in May, soon after the leaves. Polygamo-monœ cious, greenish. Of three kinds—staminate, pistillate, perfect; born on slender drooping pedicels. The calyx is light yellow green, five-lobed, divided nearly to the base; lobes linear, acute, more or less cut at the apex, often tipped with hairs, imbricate in bud. * Corolla: Wanting. There are five stamens, which are hypogynous; the filaments are white, smooth, slightly flattened and gradually narrowed from base to apex; in the bud incurved, bringing the anthers face to face, as flower opens they abruptly straighten; anthers extrorse, oblong, two-celled; cells opening longitudinally. * Pistil: ovary superior, one-celled; style two-lobed; ovules solitary. * Fruit: Fleshy drupe, oblong, one-half to three-fourths of an inch long, tipped with remnants of style, dark purple. Borne on a slender stem; ripens in September and October. Remains on branches during winter.〔 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「Celtis occidentalis」の詳細全文を読む スポンサード リンク
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