Page:Illustrations of Indian Botany, Vol. 2.djvu/183

 ILLUSTRATIONS OF INDIAN BOTANY-

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scales, forming either one or several series, free or united by the margins, dry, scariose, coriaceous, fleshy, prickly, or leafy: often furnished with an appendix. These series are either equal or unequal, imbricated or caliculate, or variously elongated.

A glomerulus is a capitulum with one or few flowers, furnished with a proper involu- crum, variously aggregated, enclosed in a general involucrum, seated on a general receptacle, the central ones flowering first, the exterior ones later or flowering out of the usual order.

The Receptacle is either paleaceous, having a chaffy scale, similar to those of the involucrum, at the exterior side of each flower — these are articulated at the base, and sometimes, in a state of monstrosity, expand into true leaves ; or semipaleaceous, the ex- terior circles of flowers only having them ; or they are epaleaceous or naked. In some capitula the receptacle is said to be Jimbriliferous, that is, each flower is embraced at the base by an irregular scaly margin; or abveolate, appearing as if honeycombed, not pro- duced into bristles, but often denticulate; or, lastly, they are areolate, where a pentagonal areola surrounds the base of each flower.

Vegetation. The plants of this family are usually herbaceous perennials, or shrubs; rarely trees; distributed all over the world, and constituting nearly one-tenth part of the vegetable kingdom. Leaves alternate or opposite, most various in their forms and divisions, but always simple, not compound. The stems (when simple), or the branches terminated by a capitulum or glomerules: the branches usually corymbose, the centre ones flowering first. The leaves under the capitula, differ from the others, and called floral or bractial, sometimes gradually passing into scales, or abruptly changed into much larger scales. Corolla some- times yellow sometimes blue in the same capitulum ; Homochromous, if all are of one colour, or Heterochromous if of different colours. When heterochromous the ray is always blue, the disk yellow, or the disk also becomes blue when, by monstrosity, the disk florets become ligulate. The proper Juices are various, sometimes milky. Taste usually bitter, astringent, or aromatic. D. C. Prod.

Affinities. Under this head I know not what to say. Viewed as a whole, the limits of the order are so strictly defined that it may justly be said to stand alone in the midst of the vegetable kingdom, like a large island in the midst of the ocean, with a few smaller ones in the neighbourhood, but still quite distinct from all. Affinities, more or less close, it certainly has, but none, so far as I am aware, with which it can be confounded, the only genus referred to it, which does not at first sight proclaim itself a member of the family, being Xanthium, and it differs so widely in general appearance and even in some points of structure, that I cannot help wondering at its being per- mitted to retain its place.

Many plants have capitate inflorescence, and some have their florets bound by an involucrum, seated on a receptacle, and with even a pappus calyx, as, for example, Dip- sacece, but they want the venation of the corolla, the valvate aestivation, the usually cohering anthers, and erect ovules of Compositae. Some, as Lobeliaceoe, have cohering anthers, but differ in almost every thing else. Many have valvate aestivation, but none have it combined with the peculiar venation and united anthers of this family. Solitary erect ovules are also met with, but uncombined with any other of the essential characters of the order. Thus we see that more remote affinities abound, but really near relations still require to be sought for.

In explanation of the very important doctrine embodied in DeCandolle's term Corolla Neuramphipetala, I shall here introduce an extract from Mr. Brown's admirable paper on Composite, published in the 12th Vol. of the Linnaean Transactions, which details the facts on which it rests.

"The whole of Compositae agree in two remarkable points of structure of their corolla; which, taken together at least, materially assist in determining the limits of the class. The first of these is its valvular aestivation ; this, however, it has in common with several other families. The second I believe to be peculiar to the class, and hither- to unnoticed. It consists in the disposition of its fasciculi of vessels or nerves; these,,