Page:Illustrations of Indian Botany, Vol. 1.djvu/20

viii whether the seed is mono: or dicotyledonous. Having by this summary process decided to which division of the system a plant belongs we proceed with our investigation. Let us suppose the plant is dicotyledonous and that we still follow DeCandolle as our guide.

He divides Dicotyledonous or Exogenous plants into 4 sub-classes the characters of which are taken from the fructification. These four are respectively named Thalaniiflorce, Caliciflorae Corolliflorae and Monochlamydeae ,

I. Thalamiflorae are distinguished by having several distinct petals and stamens inserted on the Thalamus or receptacle of the flower, and not cohering with the calyx.— (flowers hypogynous.)

The petals and stamens do however occasionally cohere as for example in Malvaceae so as in some degree to resemble those of the third class Corolliflorae, from which however in all such cases their numerous nearly distinct, carpels distinguish them.

II. Calyci florae have also several petals, either distinct or united to each other, but inserted along with the stamens on the calyx, usually through the medium of a disk lining its tube or concave portion. — (flowers pyrigynous or epigynous).

III. Corolliflorae have the petals united into one bearing the stamens and inserted on the thalamus, or receptacle (hypogynous).

IV. Monochlamydeae have either no corolla or the petals if present are united to the calyx forming together a single, not double, perigonium or verticel of flower leaves round the pistil.

Before going further it may be proper to observe, that this is a mere artificial classification intended simply to facilitate the arrangement of the orders in a linear series, and to aid in enabling us to determine to what part of that series we ought to turn to find the order of any plant under investigation. While it pretty well fulfills these objects, it must be acknowledged, that, like all such artificial combinations it is liable on the one hand to produce unnatural associations, and on the other to separate orders most nearly allied, besides presenting examples of Monochlamydeous and dichlamedyous genera in the same order. These objections, however, apply to the arrangement, only, of the orders, not to the orders themselves, which may, though individually perfectly natural, be most unnaturally placed in relation to each other, a defect, to which all systems yet proposed is more or less liable, and we may almost, assume, ever will be, when we take into consideration that families of plants like provinces of a kingdom, touch each other, not by one point only but on all sides and that we might as well expect to arrange the latter in a correct, linear series as the equally irregularly formed and closely surrounded provinces, that is the natural orders, of the vegetable kingdom. All therefore that can be looked for is well constructed and correctly defined orders or provinces, the boundaries of which should be as clearly marked out as the nature of the subjects will permit. The after arrangement of these, in such a manner as to facilitate reference, or to follow out the simile of kingdoms and provinces, to teach under what latitude and longitude we must look first for the province (the natural order) and then for the town (the genus) to which the subject of our enquiry (the species) belongs. Various plans have been tried for the attainment of this desideratum, but no one seems yet to have obtained such general favour as the one the ground work of which I have sketched, even though liable to such striking defects as those I have indicated. But to proceed.

I. .—This sub-class includes all the plants originably referred by Jussieu to his 13th class (Polypefalae hypogena) those namely with hypogynous or inferior flowers, and several petals or which has more recently received the name of Hypopetalae: that is petals inferior to the pistil or ovary. This is a large class, presenting many anomalies, but upon the whole, generally of sufficiently easy application in practice.

II. .—This sub-class is more difficult, and often not easily distinguished from either the preceding or the succeeding one. It is divided into six sections.