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be superior (Plate V. fig. 7. & 9.), as the Apple blossom. In this instance, the ovary seems to originate below the calyx, corolla, and male system; on which account it is said to be inferior in such cases, while in the opposite state it is called superior. But, in reality, the inferior ovary is only so in consequence of the tube of the calyx contracting an adhesion with its sides; and such being the case, the exactness of the description of the constant place of the pistillum as above is unshaken. This is proved in many ways. In Saxifragaceæ, the genus Leiogyne has the ovary superior; in Saxifraga itself the calyx partially adheres to the sides of the ovary, which then becomes half inferior; while in Chrysosplenium the union between the calyx and ovary is complete, and the latter is wholly inferior. Again, in Pomaceæ, the ovaries partially cohere with the calyx in Photinia, completely in Pyrus, and by their backs only in Cotoneaster; whence the ovary is half superior in the first instance, quite inferior in the second, and what is called parietal in the third. (Botanists call any thing parietal which arises from the inner lining or wall of an organ; thus in Cotoneaster the ovaries are parietal, because they adhere to the inner lining of the calyx, and in Papaver the placentæ are parietal because they originate in the inner lining of the fruit.)
Sometimes the ovary, instead of being sessile, as is usually the case, is seated upon a long stalk; as in the Passion flower and the genus Cleome. This stalk is often called the thecaphore or gynophore (also basigynium or podogynium); but it is obviously analogous either to the petiole of a leaf, or to an internodium, and the application of a special term to it appears unnecessary. Cassini calls the elongated apex of the ovary of some Compositæ le plateau.
That part of the ovary from which the ovules arise is called the placenta (trophospermium, Richard; spermaphorum, colum, receptacle of the seeds). It generally occupies the whole or a portion of one angle of each cell (Plate V. fig. 1. e, 2. c, &c.), and will be spoken of more particularly hereafter. It is sometimes elongated in the form of a little cord, as in the Hazel nut, and many Brassicaceæ: it is then called the umbilical cord (funiculus umbilicalis, podospermium).
The swelling of the ovary after fertilisation is termed grossification.
The style (tuba of old authors) is that elongation of the ovary which supports the stigma (Plate V. fig. 7. f). It is frequently absent, and then the stigma is sessile: it is not more essential to a pistil than the stalk to a leaf, or the claw to a petal, or the filament to a stamen. Anatomically considered, it consists of a column of one or more bundles of vascular tissue, surrounded by cellular tissue; the former communicating on the one hand with the stigma, and on the other with the vascular tissue of the ovary. It is usually taper, often filiform, sometimes very thick, and occasionally angular: rarely thin, flat, and coloured, as in Iris and in Canna. In some plants it is continuous with the ovary, the one passing insensibly into the other, as in Digitalis; in others it is articulated with the ovary, and falls off, by a clean scar, immediately after fertilisation has been accomplished, as in the Scirpus. Its usual point of origin is from the apex of the ovary; nevertheless, cases occur in which it proceeds from the side, as in Alchemilla, or even from the base, as in Labiatæ and Boraginaceæ. In these cases, however, it is to be understood that the geometrical and organic apices are different, the latter being determined by the origin of the style. For this reason, when the style is said to proceed from the side or base of the ovary, it would be more correct to say that the ovary is obliquely inflated or dilated, or that it is gibbous at the base of the style.
The surface of the style is commonly smooth; but in Compositæ, Campanulaceæ, and others, it is often densely covered with hairs, called collectors, which seem intended as brushes to clear the pollen out of the cells of the anthers. In Lobelia these hairs are collected in a whorl below the stigma; in Goodeniaceae they are united into a cup, in which the stigma is enclosed, and which is called the indusium (Plate V. fig. 13. b). Many styles which appear to be perfectly simple, as for instance those of the Primrose, the Lamium, the Lily, or the Borage, are in reality composed of several grown together; as is indicated by the lobes of their stigma, or by the number of cells or divisions of their ovary. In Malva an example
may be seen of a partial union only of the styles, which are distinct upwards, but united below. In speaking of styles in this latter state, botanists are accustomed to describe them as divided in different ways, which is manifestly an inaccurate mode of expression.
The stigma is the upper extremity of the style, without epidermis; in consequence of which it has, almost uniformly, either a humid or papillose surface. In the first case it is so in consequence of the fluids of the style being allowed to flow up through the intercellular passages of the tissue, there being no cuticle to repress and conceal them; in the latter case the papillæ are really the rounded sides of vesicles of cellular tissue. When perfectly simple, it is usually notched on one side, the notch corresponding with the side from which the placenta arises: see the stigma of Rosa, Prunus, Pyrus, and others. If it belongs to a single carpel, it is either undivided, or its divisions, if any, are placed side by side, as in Euphorbiaceæ, Crocus, &c.; but if it is formed by the union of the stigmas of several carpels, its lobes are either opposite each other, as in Mimulus, or placed in a whorl, as in Geranium. Such being the case, it is a general law that an apparently simple ovary, to which more than two opposite stigmas belong, is really of a compound nature; but, when the stigma of a simple carpel is two-lobed, the arms are often placed exactly opposite each other, as in Compositæ, Graminaceæ, &c., and then the apparent number of the stigmas is not the real number.
Nothing is, properly speaking, stigma, except the secreting surface of the style; it very often, however, happens, that the term is carelessly applied to other portions of the style. For example, in the genus Iris, the three petaloid lobed styles in the centre are called stigmata; while the stigma is in reality confined to a narrow humid space at the back of each style in Labiatæ, Bentham has shown that what is called a two-lobed stigma has a two-lobed style, the points only of the lobes of which are stigmatic: and in Lathyrus, and many other papilionaceous plants, Linnæan botanists call the hairy back of the style the stigma; while, in fact, the latter is confined to the mere point of the style.
Nevertheless, there are certain stigmas in which no denuded or secreting surface can be detected. Of this nature is that of Tupistra, in which the apparent stigma is a fungous mass with a surface of the same nature as that of the style; in such a stigma the mode of fertilisation forms an interesting problem, which botanists have yet to solve.
The centre of a stigma consists of tissue of a peculiar character, which communicates directly with the placenta, and which is called the conducting tissue. It is more lax than that which surrounds it, and serves for the conveyance of the fertilising matter of the pollen into the ovules. Schleiden well observes that, as a style is a portion of a leaf rolled up, or formed by a union of the edges of many leaves (as will be presently shown), the centre of the style must answer to the epidermis of the upper side of such leaf, and therefore this epidermis, modified, constitutes the conducting tissue. If the convolution or approximation of the carpels is very complete, the tissue will be a mere thread; but if it be imperfect, as in Orchidaceæ, &c., the tissue will form the lining of a funnelshaped passage from the stigma to the cavity of the ovary.
Such is a general view of the more remarkable peculiarities of the female system. This part, however, bears so important an office in the functions of vegetation, is so valuable as a means of scientific arrangement, and is liable to such a great variety of modifications, that it will be necessary now to regard it in another and more philosophical point of view. For we have yet to consider the structure of the compound pistil, and to learn to understand the exact nature of its cells, and dissepiments, and placenta, and the precise relation that these parts bear to each other; and also to prove that the necessary consequence of the laws under which pistils are constructed is, that they can be subject to only a particular course of modification, within which every form must absolutely, and without exception, fall. This enquiry would, perhaps, be less important, if none but structure of a very regular and uniform kind were to exist; but, considering the numberless anomalies that the pistil exhibits, it becomes at once one of the most difficult and most essential parts of a student's investigation.
In the days of Linnæus and Gartner, and even in those of the celebrated L. C. Richard, nothing whatever was known of this matter, and consequently the writings of those carpologists are a tissue of ingenious misconceptions. Nor did the subject become at all intelligible, notwithstanding the writings of Wolff, until the admirable treatise upon Vegetable Metamorphosis, which had been published by Goethe in 1790, but which had long been neglected, was again brought into notice, and illustrated by the skilful demonstrations of De Candolle, Turpin, Du Petit Thouars, and others.
According to these writers, the pistil is either the modification of a single leaf (fig. 122.), or of one or more whorls of such leaves (fig. 121.), which are technically called carpels. Each carpel has its own ovary, style, and stigma, and is formed by a folded leaf, the upper surface of which is turned inwards, the lower outwards, and the two margins of which develope one or a greater number of buds, which are in a rudimentary state, and are called the ovules.
A clear idea of the manner in which this occurs may be obtained from the carpel of a double cherry, in which the pistil loses its normal carpellary character, and reverts to the structure of the leaf. In this plant the pistil is a little contracted leaf, the sides of which are pressed face to face, the