condition, and no intervals of stem whatever are formed between them. The vegetative stage of youth is passed away for ever, and the plant has now entered upon the reproductive period of its life, or the
Period of Puberty.—This epoch in plant life clearly corresponds to the same interesting and critical period in human life, when man attains his greatest strength, and woman is most gentle, graceful, beautiful. “All flesh is as grass, and all the goodliness thereof is as the flower of the field.” Isaiah xl. 6.
In the flower the leaves are crowded together in order that they may communicate in a peculiar manner with each other, and in consequence of the gradual expiration of the vegetative force in that direction. Hence the change of structure or departure from the ordinary type of leaf increases as we pass from the outside to the inside of the flower; for the vegetative forces are gradually enfeebled in the flower, and reduced to zero in the centre, where the metamorphosis of the leaf is at a maximum, or the leaf attains its highest stage of organic perfection.
We select for analysis one of the more highly organised flowers, where all the parts usually described are present. We must however say that these parts, though well defined in some flowers, are more or less blended together in others. Nature laughs at all such distinctions, and we seek in vain to confine her within the fetters of an artificial nomenclature. The following distinction of parts, is, however, very convenient for beginners. The flower, then, consists of four sets of progressively metamorphosed leaves. The two outer sets which are generally the most showy, are simply the envelopes which surround the true botanical flower. They are called the calyx and corolla. Let us consider each.
The Calyx.—This, when well-defined, constitutes the outermost cluster of the floral leaves. Although greatly diminished in size, the leaves of the calyx not unfrequently retain their green colour. Individually they are called sepals (lat. sepalum, a leaf), collectively the calyx (gr. κάλυξ, a cup), because they form a cup-like involucre around the next set of leaves, which are called collectively
The Corolla (lat. corolla, a garland), and individually petals (πέταλον, a leaf). These are the most showy leaves in the cluster, constituting the part which is popularly considered as the flower. Thus the red petals of the rose, the yellow petals of the butter-cup, the white petals of the lily, constitute the corolla of those plants.
The Stamens.—These are situated immediately within the corolla. In the stamen the stalk of the leaf is converted into a filament, and the delicate portion or blade into a club-like body called an anther. This anther consists of two lobes or cells, which correspond to either side of the lamina leaf-blade, and lying between them you will notice a prolongation of the filament called the connectivum or connective, which answers to the middle of the leaf. The inside of the anther is filled with fertilising matter called pollen. The stamens are called collectively the Andrœcium (ἀνὴρ, a man, οἶκος, habitation).
The Pistil.—This consists of a leaf folded on its midrib, the two sides of the lamina or blade of which are united at their margins to form the ovary. The summit of this folded leaf denuded of its epidermis corresponds to the stigma of the pistil. The interjacent portion between the ovary and stigma is called the style. The pistils are always situated in the centre of the flower; when both stamens and pistils are present in the same flower the former always surround the latter. The ovary of the pistil is so named, because it contains the ovules, which after fertilisation are transformed into seed.
The process of fertilisation.—This takes place when all the floral leaves have arrived at maturity, and is as follows :—
When the flower is fully expanded, at first the anthers of the stamens are unruptured, moist, and closed; but, as the stamens approach maturity, the anthers become dry, open their cells, and discharge their pollen on the stigmatic surface of the pistils, which about this time exudes a clammy fluid which serves to retain the pollen-grains. These grains absorb the exuded fluid, swell out, and finally emit delicate tubes, which penetrate the loose cellular tissue of the style, and convey the fertilising fluid contents of the pollen-grains to the ovules in the ovary of the pistil. The ovules having received the impregnating matter, the embryos or miniature-plants begin to form in them, and the ovules are then gradually transformed into seed. With the discharge of the pollen, the act of fertilisation is accomplished. The vital forces from this period begin to be enfeebled, and all the phenomena mark another well-marked change in plant life, a gradual subsiding of all energetic life movements, which culminates in death and disorganisation. Our plant therefore clearly enters upon
The Period of Old Age.—In all the previous stages of its existence it was a beautiful subject for contemplation, but it is particularly interesting as a study when it approaches the close of its allotted period of life. What! when its leaves are withering and falling from its stem, when its flowers are losing their brilliant hues and inimitable colouring, and when