XXXI.—AURANTIACEÆ.
This very beautiful, and on account of its fragrant flowers and delicious fruit, much admired order, of which the orange with its numerous varieties of lemons, limes, citrons, pumplemoses &c form the type, is generally well known in India (to which country indeed it almost exclusively belongs) even to the most casual observers of plants. But though so generally known in its more perfect forms, it is not always easy to recognize those more remote from the type of the family.
The order generally is composed of handsome flowering ever-green trees and shrubs, occasionally armed with strong spines, abounding in glands filled with volatile oil, usually very conspicuous in the leaves when held between the eye and the light, and exhaling a fragrant odour. Their leaves are alternate, simple, or compound. In the former as in the latter instance the petiols are jointed, indicating a tendency to become compound. So constantly is this the case, that simple leaves with such petiols are sometimes described as "pinnate reduced to the terminal leaflet." The petiols are often dilated or winged. The flowers are bisexual, for the most part white variously arranged in solitary and axillary flowers, or in racemes, panicles, corymbs, &c.
The calyx is short, more or less urceolate, or campanulate at the base, 3-5 lobed, withering. Petals equalling the number of the lobes of the calyx and alternate with them, inserted outside of the torus, broad at the base, distinct, or sometimes cohering, deciduous, imbricated in aestivation. Stamens equal or double the number of the petals, or more rarely, are very numerous and indefinite, inserted in a single series into the torus : filaments compressed, either altogether free or united into a tube, or variously polyadelphous, subulate, and free at the point. Anthers 2-celled, attached by the base, or the middle of the back, dehising longitudinally, introrse. Ovary free, 2-3-5 or many celled, with one or several ovules in each. Style cylindrical, or rarely wanting. Stigma large, somewhat lobed, or flat and spread over the apex of the ovary. "Fruit (an orange) consisting of several (or 1 by abortion) membranacious carpels, with or without an internal pulp, and surrounded by a thickish indehiscent rind, abounding in vesicles full of volatile oil. Seeds attached to the inner angle of the carpels, solitary, or numerous, usually pendulous : raphe and chalaza usually very conspicuous : Albumen none. Embryo straight, radicle next the hilum, partly concealed within the cotyledons. Cotyledons large, thick and amygdaline."
Affinities. The plants of this order are most readily known by the number of oily receptacles, which are dispersed all over them; the leaves, sepals, petals, and fruit equally partaking of them; by their deciduous petals, and compound leaves, and frequently winged petiols. By these peculiarities they are nearly related to Amyrideœ and Zanthoxylaceœ, from neither of which is it always easy to distinguish them, except by the fruit. Several species referred by Roxburgh to his genus Amyris, actually belong to this order. From the former they are distinguished by the numerous, not solitary, cells of the ovary, and by their baccate, not drupacious, or saniaroid, or legume-like fruit : from the latter their bi, not usually unisexual flowers, and their indehiscent pulpy fruit, not 2-valved dehiscent capsules seated on a gynophore, with a solitary shining black seed.
Geographical Distribution. Tropical Asia and her islands seem to be the native country of the order, a few only having been found indigenous elsewhere, of these two or three are from Madagascar, an island in which many other associates of the Indian Flora are found. DeCandolle in his Prodromus, excluding Aglaea, enumerates 43 species for the whole order : G. Don, who published some years later, raises the number to 60, but many of these doubtful : Blume found 21 in Java: Wallich's list has 37 : and 24 are described in our Prodromus as natives of the Indian Peninsula : one or two have been since added to the Peninsular list and I have several species from Ceylon, and some from Mergui. One species only, is found to withstand exposure to frost and snow, the Limonia lauriola, Wallich (PI. As. rar,) which is found on the tops of cold and lofty mountains, where it is for some months of the year buried under the snow.
Properties and Uses. The properties of the orange in all its protean forms of lemon,
