The chloroplast genome , and therefore the maternal line, is that of pomelo. There are many related hybrids including of mandarins and sweet orange.
The sweet orange has had its full genome sequenced. The orange originated in a region encompassing Southern China , Northeast India , and Myanmar ; the earliest mention of the sweet orange was in Chinese literature in BC. Orange trees are widely grown in tropical and subtropical areas for their sweet fruit. The fruit of the orange tree can be eaten fresh or processed for its juice or fragrant peel.
Oranges, variously understood, have featured in human culture since ancient times. By the 17th century, an orangery had become an item of prestige in Europe, as seen at the Versailles Orangerie. The orange tree is a relatively small evergreen , flowering tree, with an average height of 9 to 10 m 30 to 33 ft , although some very old specimens can reach 15 m 49 ft.
Inside and attached to the rind is a porous white tissue, the white, bitter mesocarp or albedo pith. 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 , not ripening off the tree.
The Citrus sinensis group is subdivided into four classes with distinct characteristics: common oranges, blood or pigmented oranges, navel oranges, and acidless oranges.
