ILLUSTRATIONS OF INDIAN BOTANY.
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LXXXVII.— ASTERACE.E.
Composites — Synantherece.
This is "by far the largest and also about the most natural of the whole series of natural orders of dicotyledonous plants. The elaboration and publication of the vast mass of material placed at the disposal of the late Professor DeCandolle, for the eluci- dation of this family, occupied that most eminent and indefatigable Botanist nearly eight years. The result of these labours has, as might be expected from his talents and as- siduity, put the world in possession of the most masterly account of this gigantic order that has ever appeared. His monograph is said to include 8500 species, and though the last part was published so late as 1838, there has already been great additions made and more are daily being added, so that I presume 10,000 species may already be set down as the number known to belong to it. Many of these species are doubtless de- scribed twice over and some, perhaps, even oftener than that, under different names, but I dare say it will as often be found that two or three species are included under one, owing to several persons describing, in different places, distinct species under the same name, an event of frequent occurrence, but not easily detected except by a comparison of authentic specimens which are not always attainable.
It is an interesting fact in natural history that out of the immense mass of species congregated under a common denomination, and presenting among themselves almost every form of vegetation, yet so constant are the distinctive family characters by which they are bound together, that almost any one species being thoroughly known and these char- acters clearly understood, there is no difficulty in afterwards recognizing any other of the whole group as belonging to this family. These characters may be summed up in ftw words : — Flowers, or florets, as they are usually called, in heads, surrounded by an involucrum and seated on a common receptacle : an obsolate, chaffy, or pappus, calyx : monopetalous superior corolla : united anthers, forming a tube round the style : and a 1-celled ovary with a single erect ovule.
Numerous other peculiarities belong to the vfamily as will be seen from a perusal of the following very extended descriptive, or natural, character which I introduce in full from DeCandoUVs Prodromus, after the ordinary "character of the order," but the above com- prehends the more obvious essential peculiarities of the order. Those, however, require to be taken together to constitute a true Compositous plant, for each taken separately is found in other families, but never the whole.
Character of the Order. Flowers (florets) unisexual or hermaphrodite, collected in dense heads upon a common receptacle, surrounded by an involucre. Bracts either present or absent ; when present stationed at the base of the florets, and ealled paleae of the receptacle. Calyx superior, closely adhering to the ovary, and undistinguishable from it ; its limb either wanting or membranous, divided into bristles, paleae, hairs, or feathers, and called pappus. Corolla monopetalous, superior, usually deciduous, either ligu- late, or funnel-shaped; in the latter case 4- or 5-toothed, with a valvate aestivation. Sta- mens equal in number with the teeth of the corolla and alternate with them; the anthers cohering into a cylinder. Ovary inferior, 1-celled, with a single erect ovule; style simple;' stigmas 2, either distinct or united. Fruit a small, indehiscent, dry pericarp, crowned with the limb of the calyx. Seed solitary, erect ; embryo with a taper inferior radicle ; al- bumen none. — Lindley.
Natural Character. Calyx tubular adhering to the ovary; tube sometimes only equalling the ovary (fruit erostrate), sometimes prolonged beyond (fruit rostrate), the limb or pappus sometimes wanting, or reduced to a mere margin; sometimes, but rarely foliaceous, sometimes scarcose; entire, dentate, lobed, or more frequently passing into chaffy gcales or bristles, which are either simple, branched, denticulate or feathery; one, two
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