The leaves, calyx, and petals of the Orange, if held up to the light, appear covered with little dots. These dots are cells, covered with a transparent membrane, and filled with a kind of oil, which is exceedingly fragrant. The rind of the fruit is covered with similar cells, filled with a pungent oily liquid. The leaves are smooth and shining; and they are articulated; that is, they can be separated from the petiole or footstalk without lacerating them. In most of the species, the petioles are winged; that is, they are dilated into little leaves on each side (see d in fig. [122]). The different species vary chiefly in the number of stamens, the thickness of the rind, the shape of the fruit, and in the wings of the petioles. In the Citron these wings are wanting entirely, and instead of them there are spines in the axils of the leaves; there are generally forty stamens, and the rind of the fruit is very thick. In the sweet Lime, the petioles are slightly winged, and there are about thirty stamens; the fruit is small and round, with a slight protuberance at one end like that of the Lemon, and the pulp is sweet. In the Lemon the petioles are somewhat winged, the flowers have about thirty stamens; the fruit is oblong, with an acid pulp, and a thin rind. The Sweet Orange has winged petioles, about twenty stamens, and a fruit with a thin rind and sweet pulp; and the Seville Orange differs principally in having a thicker rind and bitter pulp. The China, St. Michael, and Malta Oranges, with many others, are all varieties of the Sweet Orange (Citrus Aurantium); and there are many other species, which I have not thought it necessary to describe.—All the species above-mentioned are natives of Asia, and most of them of China, but they have been so long cultivated in Europe and America, as to have become almost naturalised.
ORDER XXXVIII.—HYPERICINEÆ.—THE HYPERICUM TRIBE.
The genus Hypericum, or St. John’s Wort, agrees with the orange in having its leaves full of transparent cells; but these cells are filled with a yellow, resinous juice, resembling gamboge in its medicinal properties, and having a very disagreeable smell. There are five petals in the corolla; and the calyx consists of five sepals, which are unequal in size and shape, and joined together for only a short distance. Like the orange the filaments grow together at the base, in separate clusters or bundles; but in the Hypericum these clusters are so perfectly distinct, that the stamens may be readily separated into three or five bundles (according to the species), by slightly pulling them. The capsule is dry, and of a membrane-like texture, and it consists of three or five carpels, containing many seeds, and each having a separate style, and a pointed stigma. The flowers are very showy, from their large golden yellow petals and numerous stamens. The genus Androsæmum, the Tutsan, or Park-leaves, has been separated from Hypericum on account of its fruit being one-celled and one-seeded, with a fleshy covering, which yields a red juice when pressed. H. calycinum, with large yellow flowers and five tufts of stamens, is the handsomest species; but H. perforatum is the true St. John’s Wort, which the country people used formerly to gather on midsummer eve, as a preservative against witchcraft.
ORDER XXXIX.—GUTTIFERÆ.—THE MANGOSTEEN TRIBE.
The only genus in this order that contains plants interesting to the English reader is Garcinia; and the most remarkable species are G. Mangostana, the Mangosteen, said to be the most delicious fruit in the world, and G. Cambogia, the tree producing the gamboge, which is a kind of gum that oozes out from the stem. Both are natives of the East Indies.
ORDER XL.—MARCGRAAVIACEÆ.