Botany Lesson 1 - The Parts of a Plant

Plants are chiefly made up of three parts, namely of root, stem and leaves. These are called the plant’s organs, that is, its instruments. And as these parts all that any plant needs for its growth, or vegetation, they called the organs of vegetation.

Plants also produce flowers, from which comes the fruit, and from this, the seed. These take no part in nourishing the plant. Their use is to enable it to give rise to new individuals, which increase the numbers of that kind of plant, to take the place of the parent in due time, and to keep up the stock; that is, to reproduce and perpetuate the species. So the flower with its parts, the fruit, and the seed, are called the plant's organs of reproduction. 

The root is the part which grows downwards into the ground, and takes in nourishment for the plant from the soil. It commonly branches again and again as it grows: its smaller branches or fibres are named rootlets. Real roots never bear leaves, nor anything besides root-branches or rootlets.

The stem is the part which grows upwards, and bears the leaves and blossoms. At certain fixed places the stem bears a leaf or a pair of leaves.

Leaves are generally flat and thin, green bodies, turning one face upwards towards the sky, and the other downwards towards the ground. They make the foliage.

We see that a plant has a body or trunk (in scientific language, an axis), consisting of two parts, - an upper and a lower. The lower is the root: this fixes the plant to the soil. The upper is the stem: this rises out of the ground, and bears the leaves, which are hung out on the stem in the light and air.

The root takes in a part of the plant’s food from the soil: this the stem carries to the leaves. The leaves take in another part of the plant’s food from the air. And in them what the roots absorb from the ground and what they themselves absorb from the air, are exposed to the sunshine and digested; that is, changed into something proper to nourish the plant.

For there is no nourishment in earth, air, and water as they are; but vegetables have the power of making these into nourishment. And out of this nourishment it prepares, the plant makes more growth. That is, it extends the roots farther into the soil, and sends out more branches from them, increasing its foothold and its surface for absorbing; while, above, it lengthens the stem and adds leaf after leaf, or shoots forth branches on which still more leaves are spread out in the light and air.

So the whole herb, or shrub, or tree, is built up. A tiny herb just sprouted from the seed and the largest tree of the forest alike consist of root, stem, and leaves, and nothing else. Only the tree has larger and more branching stems and roots, and leaves by thousands.

After having attended in this way to its nourishment and growth for a certain time, the plant sets about reproducing itself by seed. And for this purpose, it blossoms. Many plants begin to blossom within a few weeks after springing from the seed. All our annuals, of which the garden morning glory is one, blossom in the course of the summer. Biennials such as carrot, parsnip, mullein and the common thistle, do not flower before the second summer; and shrubs and trees, and some herbs, do not begin until they are several years old.

The object of the flower is to form the fruit. The essential part of the fruit is the seed. And the essential part of the seed is the germ or embryo it contains. The germ or embryo is a little plantlet in the seed, ready to grow into a new plant when the seed is sown. Let us notice these organs one after another, beginning with the flower.

Flowers are the most interesting to the botanist; who not only admires them for their beauty, the exquisite arrangement and forms of their parts, and the wonderful variety they exhibit, but also see in the blossoms much of the nature or character of the plant, and finds in them the best marks for distinguishing the sorts of plants and the family they belong to. So let the student learn at once what the parts of a flower are.

A flower, with all the parts present, consists of calyx, corolla, stamens and pistils. One from the morning glory will serve for an example. Here is one taken off and shown, the corolla separated from the calyx.

The calyx and the corolla are the floral envelopes, or the leaves of the flower. They cover the bud and protect the stamens and pistils, which are the essential organs of the flower, because both of these are necessary to forming the seed. 

The calyx – the Latin name for “flower cup”, is the cup or outer covering of the blossom. It is apt to be green and leaf-like. The corolla is the inner cup, or inner set of leaves, of the flower. It is very seldom green, as the calyx commonly is, but is coloured, i.e. of some other colour than green, and of a delicate texture. So it is the most showy part of the blossom. 

You saw the corolla of the morning glory whole. Here is the same, split down and spread open to show the stamens. 
The stamens in this flower grow fast to the bottom of the corolla. There are five stamens in the morning glory. Each stamen consists of two parts, namely, a filament and an anther. 

The filament is the stalk; the anther is a little case, or hollow body, borne on the top of the filament. It is filled with a powdery matter, called pollen. The next picture shows a separate stamen on a larger scale: the filament and the anther, out of which pollen is falling from a slit or long opening down each side.