ORANGE. The plant that produces the familiar fruit of commerce is closely allied to the citron, lemon and lime; all the cultivated forms of the genus Citrus (family Rutaceae) are nearly related. The numerous kinds of orange chiefly differing in the external shape, size and flavour of the fruit may all probably be traced to two well-marked species—the sweet or China orange, Citrus sinensis, and the sour Seville orange or bigarade, Citrus Aurantium.
The SOU, SEVILLE or BIGARADE ORANGE, C. Aurantium, C. Aurantium, is a rather small tree, rarely exceeding 3o ft. in height. The green shoots bear sharp axillary spines, and alternate ever green oblong leaves, pointed at the extremity, and with the mar gins entire or very slightly serrated ; they are of a bright glossy green tint, the stalks distinctly winged and, as in the other species, articulated with the leaf. The fragrant white flowers appear in the spring months, and the fruit, usually round or spheroidal, does not perfectly ripen until the following spring, so that flowers and both green and mature fruit are often found on the plant at the same time. The bitter aromatic rind of the bigarade is rough, and dotted closely over with concave oil-cells; the pulp is acid and more or less bitter in flavour.
The Sweet or common China Orange (C. sinensis) including the Malta or Portugal orange, has the petioles less distinctly winged, and the leaves more ovate in shape, but chiefly differs in the fruit, the pulp of which is agreeably acidulous and sweet, the rind com paratively smooth, and the oil-cells convex. The ordinary round shape of the sweet orange fruit is varied greatly in certain vari eties, in some being greatly elongated, in others much flattened; while several kinds have a conical protuberance at the apex, others are deeply ribbed or furrowed, and a few are distinctly "horned" or lobed, by the partial separation of the carpels. The two species of orange reproduce themselves true to species by seed ; and, where hybridizing is prevented, the seedlings of the sweet and bitter or ange retain respectively the more distinctive features of the parent plant.
History.—Though now the most widely cultivated of Citrus fruits and grown in most of the warmer parts of the world, and apparently in many completely naturalized, the diffusion of the orange has taken place in comparatively recent historical periods. To ancient Mediterranean agriculture it was unknown; and, though the later Greeks and Romans were familiar with the citron as an exotic fruit, their "Median apple" appears to have been the only form of the citrine genus with which they were ac quainted. The careful researches of Gallesio have proved that India was the country from which the orange spread to western Asia and eventually to Europe. Oranges are at present found ap parently wild in the jungles along the lower mountain slopes of Sylhet, Kumaon, Sikkim and other parts of northern India, and, according to Royle, even in the Nilgiri hills; the plants are gener ally thorny, and present the other characters of the bitter variety, but occasionally wild oranges occur with sweet fruit ; it is, how ever, doubtful whether either sub-species is really indigenous to Hindustan, and De Candolle is probably correct in regarding south China and the Indo-Chinese peninsula as the original home of the orange. Cultivated from a remote period in south-eastern Asia, it was carried to south-western Asia by the Arabs, probably before the 9th century, towards the close of which the bitter or ange seems to have been well known to that people ; though, ac cording to Mas'ildi, it was not cultivated in Arabia itself until the beginning of the loth century, when it was first planted in 'Oman, and afterwards carried to Mesopotamia and Syria. It spread ulti mately, through the agency of the same race, to Africa and Spain, and perhaps to Sicily, following everywhere the tide of Moham medan conquest and civilization. In the 12th century the sour orange or bigarade was abundantly cultivated in all the Levant countries, and the returning soldiers of the Cross brought it from Palestine to Italy and Provence.