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The orange (specifically, the sweet orange) is the fruit of the citrus species ''Citrus'' × ''sinensis'' in the family Rutaceae.〔(【引用サイトリンク】title=Citrus ×sinensis (L.) Osbeck (pro sp.) (maxima × reticulata) sweet orange )〕 The fruit of the ''Citrus × sinensis'' is considered a sweet orange, whereas the fruit of the ''Citrus × aurantium'' is considered a bitter orange. The sweet orange reproduces asexually (apomixis through nucellar embryony); varieties of sweet orange arise through mutations.〔 The orange is a hybrid, between pomelo (''Citrus maxima'') and mandarin (''Citrus reticulata''). It has genes that are ~25% pomelo and ~75% mandarin; however, it is not a simple backcrossed BC1 hybrid, but hybridized over multiple generations. The chloroplast genes, and therefore the maternal line, seem to be pomelo.〔 The sweet orange has had its full genome sequenced.〔 Earlier estimates of the percentage of pomelo genes varying from ~50% to 6% have been reported.〔 Sweet oranges were mentioned in Chinese literature in 314 BC.〔 , orange trees were found to be the most cultivated fruit tree in the world.〔Morton, J., (''Fruits of Warm Climates'' ) (1987) Miami, FL, pp. 134–142.〕 Orange trees are widely grown in tropical and subtropical climates for their sweet fruit. The fruit of the orange tree can be eaten fresh, or processed for its juice or fragrant peel.〔(Citrus sinensis information from NPGS/GRIN )〕 , sweet oranges accounted for approximately 70% of citrus production.〔(''Organisms'' ). Citrus Genome Database〕 In 2013, 71.4 million metric tons of oranges were grown worldwide, production being highest in Brazil and the U.S. states of Florida and California. == Botanical information and terminology == (詳細はcitrus trees belong to the single genus ''Citrus'' and remain almost entirely interfertile. This means that there is only one superspecies that includes grapefruits, lemons, limes, oranges, and various other types and hybrids.〔(Superspecies )〕 As the interfertility of oranges and other citrus has produced numerous hybrids and cultivars, and bud mutations have also been selected, their taxonomy is fairly controversial, confusing or inconsistent.〔 The fruit of any citrus tree is considered a hesperidium, a kind of modified berry; it is covered by a rind originated by a rugged thickening of the ovary wall.〔Bailey, H. and Bailey, E. (1976). ''Hortus Third''. Cornell University MacMillan. N.Y. p. 275.〕〔(Seed and Fruits )〕 Different names have been given to the many varieties of the genus. ''Orange'' applies primarily to the sweet orange – ''Citrus sinensis'' (L.) Osbeck. The orange tree is an evergreen, flowering tree, with an average height of , although some very old specimens can reach .〔 Its oval leaves, alternately arranged, are long and have crenulate margins.〔(Citrus sinensis – Encyclopedia of Life )〕 Although the sweet orange presents different sizes and shapes varying from spherical to oblong, it generally has ten segments (''carpels'') inside, and contains up to six seeds (or ''pips'')〔(pip – Definition with thesaurus, examples, audio and more )〕 and a porous white tissue – called pith or, more properly, mesocarp or albedo—lines its rind.〔(pith – Definition with thesaurus, examples, audio and more )〕 When unripe, the fruit is green. The grainy irregular rind of the ripe fruit can range from bright orange to yellow-orange, but frequently retains green patches or, under warm climate conditions, remains entirely green. Like all other citrus fruits, the sweet orange is non-climacteric. The ''Citrus sinensis'' is subdivided into four classes with distinct characteristics: common oranges, blood or pigmented oranges, navel oranges, and acidless oranges.〔''Home Fruit Production – Oranges'', Julian W. Sauls, Ph.D., Professor & Extension Horticulturist, Texas Cooperative Extension (December, 1998), (aggie-horticulture.tamu.edu )〕 Other citrus groups also known as oranges are: * Bitter orange (''Citrus aurantium''), also known as Seville orange, sour orange (especially when used as rootstock for a sweet orange tree), bigarade orange and marmalade orange. Like the sweet orange, it is a pomelo x mandarin hybrid.〔"Plant Profile for Citrus ×aurantium L. (pro sp.), http://plants.usda.gov/java/profile?symbol=CIAU8〕 * Bergamot orange (''Citrus bergamia Risso''), grown mainly in Italy for its peel, producing a primary essence for perfumes, also used to flavor Earl Grey tea. It is a hybrid, probably bitter orange x limetta.〔(RFLP Analysis of the Origin of ''Citrus Bergamia'', ''Citrus Jambhiri'', and ''Citrus Limonia'' )〕 * Trifoliate orange (''Poncirus trifoliata''), sometimes included in the genus (classified as ''Citrus trifoliata''). It often serves as a rootstock for sweet orange trees and other ''Citrus'' cultivars.〔(【引用サイトリンク】title=Plant of the Week. Hardy Orange or Trifoliate Orange. Latin: Poncirus trifoliat )〕 * Mandarin orange (''Citrus reticulata'') is an original species of citrus, and is a progenitor of the common orange. An enormous number of cultivars have, like the sweet orange, a mix of pomelo and mandarin ancestry. Some cultivars are mandarin-pomelo hybrids, bred from the same parents as the sweet orange (e.g. the tangor and ponkan tangerine). Other cultivars are sweet orange x mandarin hybrids (e.g. clementines). Mandarin traits generally include being smaller and oblate, easier to peel, and less acidic.〔(Tangerines (mandarin oranges) nutrition facts and health benefits )〕 Pomelo traits include a thick white albedo (rind pith, mesocarp) that is more closely attached to the segments. Orange trees generally are grafted. The bottom of the tree, including the roots and trunk, is called rootstock, while the fruit-bearing top has two different names: budwood (when referring to the process of grafting) and scion (when mentioning the variety of orange).〔(Scion – Definition and More from the Free Merriam-Webster Dictionary )〕 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「orange fruit」の詳細全文を読む スポンサード リンク
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