Part 19

Cruciate (Like a Cross), Cuckoo-flower.]

Within the corolla are placed the "stamens" (male reproductive organs) these consist generally of two parts, the head and stalk, the former called the "anther" and the latter the "filament," which last is sometimes absent, and the anther is said to be "sessile;" on the surface of the anther is the "pollen" or fertilising dust.

Within the centre of the flower is the "pistil" (female reproductive organ), this consists of one or several cells called "ovaries," from the pistil a tube rises, having an expanded end called the "stigma," it is by the application of the pollen dust to this stigma that the ovaries are fertilised, and the various insects, especially bees, who seek for honey, shake off by their movements the pollen from the anthers and cause it to be applied to the stigma, thus unconsciously performing a necessary office for the plant while they rob it of that only which is not required.

The stamens are sometimes separate, sometimes bound up into one or more bundles, and are placed in various situations, names are given to describe such arrangements as follows:--

Stamens in one bundle, Monadelphous. Stamens in two bundles, Diadelphous. Stamens in more than two bundles, Polyadelphous. Filaments placed directly below the pistil, Hypogynous. Placed upon the sides of the calyx, Perigynous. On the sides of the corolla, Epipetalous. On the top of the ovary, Epigynous.

When the ovaries are fertilised the flower dies and they begin to enlarge and ripen to form the fruit, which is the pistil enlarged, and contains the ovules ripened into seeds.

The fruits of different plants are known by various names according to the state of development of the various parts composing them. If the ripe fruit split open so as to let out the seeds (as in the common pea) it is called "dehiscent," if it do not so split (as in the apple) it is said to be "indehiscent;" the outer part of fruit is called the "pericarp," and this may be soft and fleshy as in the apple or cherry, or hard as in the filbert. The following are the names of the principal varieties of fruit:--

Gland (Acorn).

Legume (Pea).

Stobule (Hop).

Drupe (Plum).

Berry (Currant).

Capsule (Poppy).

Siliqua (Shepherd's Purse, Wallflower).

Eterio (Strawberry).

Nut (Hazel-nut).

Caryopsis (Wheat).]

The seed is the ovule ripened, it contains the germ of the future plant, called the "embryo," the outer part of the seed is called the "testa," and the space between this and the embryo is generally filled with starchy matter called the "albumen." The embryo consists of the plumule or stem, the "radicle" or root, and the cotyledons or leaves of the future plant; when the seed has but one cotyledon it is called "monocotyledonous" and when it has two "dicotyledonous."

Flowers are arranged in various ways upon the plants which produce them, and receive names accordingly; the whole arrangement of flowers is called the "inflorescence."

The following are the principal forms of inflorescence:--

The UMBEL, in which all the flower-stalks (pedicels) radiate from one point, as in the carrot (daucus carota). Umbels are sometimes compound, that is, the flowers are placed in umbels at the end of stalks themselves radiating from a point and so forming an umbel, as in the Hemlock (Conium maculatum).

The SPIKE, is that kind of infloresence in which all the flowers are seated without stalks upon a general peduncle or axis, as in the Plantain (Plantago media), in which the spike is entire, or as the Lavender (Lavandula Vera), in which the spike is interrupted, that is, the inflorescence is not continuous.

CATKIN, or AMENTUM, is the same as a spike, but in which the flowers are imperfectly developed, as in the Hazel (Corylus), Willow (Salix), White Poplar (Populus Alba), &c.

The RACEME has the inflorescence placed along a common axis or centre, the same as a spike, but with the flowers placed upon stalks instead of being sessile, as in Water-cress (Nasturtium officinale) and Red Currant (Ribes rubrum).]

The CORYMB is a form of inflorescence pretty much the same as raceme, but the flowers of which proceed upwards till they are all on a level, as in Candy-tuft (Iberis).

The PANICLE, the same as the raceme, but having the flower stalks themselves divided into branches, as in Creeping Soft Grass (Holcus mollis). This and the spike are the most usual form of inflorescence found among grasses, in many of which the panicle, however, is often contracted almost to a spike.

The CYME, this resembles the panicle shortened in such a manner as to become flattened or almost corymbose, as in the Elder Tree (Sambucus nigra), in which there are five principal stalks of inflorescence.

CAPITULUM, in which the flowers arise from a broad round head or receptacle as in the composite flowers, such as Chamomile (Anthemis nobilis); in such flowers the star-like ray of florets are called the florets of the ray, and those composing the centre the florets of the disc.