Chapter VI: Flowers

Instead of looking at flowers as bright and beautiful objects made to be a source of continual delight in our daily lives, though such they truly are, we will rather now, for purposes of study, consider them as the means by which the plant carries out the purpose of its creation, namely, to perfect its seed and thus perpetuate its species.

In the life-history of shrubs, trees, and plants we find this is their one aim, and that everything else is subservient to it.

The stamens and pistil being of essential importance in forming the seed, we find them placed for safety in the centre of the flower; folded round them are the petals or coloured parts of the flower, and outside these again are the green sepals, or leaves of the calyx.

These two sets of enfolding leaves are called “floral envelopes,” because they fold over and protect the central organs, the stamens and the pistil.

We will select a buttercup as a type, and taking it to pieces we will try to learn the names and uses of its various parts.

The outside is a greenish-yellow cup which is called the calyx.

The divisions of this little green cup are called sepals, and their office is to protect the five bright yellow leaves within, which are called petals when we speak of them singly, but, taken all together, form the corolla.

In the buttercups the petals are all separate, but if we look at a primrose we shall see that the corolla is in one piece, united in a tube; so also is the calyx.

The botanical term for a corolla thus formed is _gamopetalous_, a long word but easily understood when we know that _gamos_ means united; a flower with petals in one instead of many divisions is more easily referred to by this word than if we had each time to express it by a sentence.

Gathering a newly-opened flower, we can see at a glance that the sepals are placed quite below the central green organs of the flower, and that they are in no way influenced by the petals; we also see that the petals are entirely separate from the other parts of the flower, and we learn, as the result of our examination, that the parts of the buttercup are _free_. To express this botanically we prefix the word “poly” to the words sepals and petals, and so we get _polysepalous_, meaning that the sepals are quite free and distinct, and _polypetalous_ referring to the same condition of the petals.

Now, having removed the petals and sepals, we can proceed to study the other parts of the flower.

First we find a great number of little yellowish stalks tipped with tiny pouches; these are the stamens, and in the little pouches (anthers) the yellow powder termed pollen is developed. We will carefully take away these stamens, and note in so doing that they are all distinct and all sprung below the green central part. Like the sepals and petals, we find the stamens are free and uninfluenced by the other parts. If we again compare this with a primrose-flower we shall find a difference; the stamens of the primrose spring from the petals and are therefore called _epipetalous_ (_epi_ upon, a petal). Again in the sweet-pea or scarlet runner we find the stalks of the stamens are all joined together. We now have left upon the flower-stalk the little central green parts previously mentioned; there are quite a number of them; each one is distinct from its neighbour and is free. These bodies are known as carpels, they are large at one end and taper to a curved point at the other, the broad end being attached to the stem. Collectively these carpels constitute the _pistil_, and because the carpels are apart and free it is said to be _apocarpous_.

The flower of the little woodsorrel (_Oxalis acetosella_) will help us to understand better the arrangement of the carpels. If we take away the sepals, petals and stamens, we shall have only the carpels left, and these are five in number. They are in the same position as those of the buttercup, but they are not separate, they are joined by their inner surfaces. We can plainly see that this is the case, since each carpel is distinctly outlined and there are five little tapering ends (stigmas). The pistil in this case is said to be _syncarpous_.

Names are given to express some quality, and they often draw our attention to interesting facts about the plant’s mode of growth or the place where it is found; for instance, the pretty blue nemophila is so called from _nemos_, a grove, and _philo_, I love, because it delights in shady places.

Geranium is derived from _geranos_, a crane, because the fruit of some of the species resemble the beak of that bird.

Some plants are named after famous botanists, as _Linnæa_ after Linnæus.

Others derive their names from their mode of growth, as stone-crop, which is called sedum, from _sedo_, I sit, the plant having scarcely any stalk, and sitting, as it were, on walls and rocks.

These instances will show that it is well worth while to study names and learn their meanings, as they often throw so much light upon the history of a plant.

In the flowers of bulbous plants we find that the calyx and petal leaves are frequently alike in colour and texture; in that case the three sepals and three petals, of which they usually consist, are spoken of as a perianth.

In looking at the brilliant colouring of a flower we should hardly imagine that the petals have to some extent the nature of leaves, and under certain conditions may be changed to the green colour and form of ordinary leaves.

In very wet seasons we may sometimes find rose-buds with the sepals of the calyx developed into perfect green leaves. The floral envelopes therefore possess the nature of true leaves.

The brilliant scarlet so-called flowers of the poinsettia are really coloured bracts, the true flower being the small inconspicuous blossom in the centre.

In the chapter on leaves we saw that bracts are those small imperfectly-shaped leaves in the axils of which flowers are placed. They are usually green, but may be also brilliantly tinted as in the mauve-coloured Bougainvillia, the bright violet spikes of the _Salvia Hormineum_, and also pure white as in the spathe of the arum.

By special cultivation flowers can be made double, for excess of nourishment will cause the plant to multiply its petals. Instead of the five pink petals of the wild rose we find one of our garden roses bearing as many as eighty or a hundred petals.

Double flowers but rarely produce seeds, because the stamens and pistil have been turned into petals, and as there is no need to attract insects for fertilising purposes, there is no secretion of honey, and therefore we scarcely ever see honey-bees in double flowers; they are wise enough to know that their visits to them would be in vain.

In composite flowers such as asters and sunflowers the change, when they are double, occurs in several ways.

The centre may become filled with florets similar to those in the outside ring, or the florets in the middle may become larger or of a different colour.

These various changes may be readily observed in the cultivated chrysanthemums, in which every form and variety of flowering can be traced.

When the pollen has reached the pistil the flower begins to fade, because its end has been attained; nature, however, has such variety in even the smallest of her operations that the passing away of a flower is accomplished in different ways. In the primrose the corolla withers and drops to the ground. The flower of the spiderwort, one of our common garden plants, becomes pulpy as it fades, in this way resembling the pineapple plant, the flower of which eventually becomes the luscious succulent fruit.

The poppy is proverbial for its fleeting petals, which scarcely last more than a few hours, a passing wind soon scattering them far and wide.

“Pleasures are like poppies spread,
You seize the flower, its bloom is shed!
Or like the snow-fall in the river,
A moment white—then melts for ever.” (+Burns.+)

Some flowers, as the hydrangea, have persistent petals, which simply lose their brilliant tints and become tough and brown.

The calyx of the physalis or winter cherry continues to grow after the flowers are fertilised until the round balloon-like bag is formed in which the fruit is enclosed.

We will now examine the parts of a flower separately, beginning with the calyx.

In the buttercup the calyx consists of one whorl or ring of five sepals.

In the strawberry there are two whorls of sepals, and in the cotton plant there are three whorls forming its green calyx.

There are also variations in the mode of flower expansion.

As a poppy-bud opens it detaches its calyx from the stem, and the sepals fall off (the calyx is therefore called caducous, a term which means ready to drop off).

Many flowers retain the calyx until the petals wither and it falls off with them. It is then called a deciduous calyx.

Others again have a permanent calyx, so that when, as in the primrose, the corolla withers and drops off, the sepals close over the seed-vessel and protect it until the seeds are matured; this would be called botanically a persistent calyx.

The best way to learn the names of the different parts of a flower is to pull it carefully to pieces and arrange the separate organs on a thin card. They can be tacked on to the card with a stitch or two of fine thread, and when the lesson is over, if the card is placed between sheets of blotting-paper under a weight, the flower dissections will dry and be useful for reference later on.

Each separate part of the flower should have its name neatly written beneath it, so that when a good many different flowers have been thus dissected they may be compared and the variations in form and position duly noted.

A wallflower will be a good subject for our dissection.

At the back of the petals we first take off the calyx, which consists of four divisions called sepals. We then pull off the four yellow petals, and as they are placed in the form of a cross it shows that this plant is a crucifer, or cross-bearer, one of a very large natural order, _Cruciferæ_,[16] none of which are poisonous and very many are useful food-plants, such as cabbage, turnip, watercress, and cauliflower. Now there remain six stamens—four long and two shorter ones; these last rise outside of and alternate with two nectaries or honey-glands.

[16] All cross-shaped flowers do not, however, belong to this order.

The stems of the stamens are called filaments, from _filum_, a thread; and the upper part, containing yellow powder, is called the anther, the proper name for the powder itself being pollen.

In the centre of the flower is the pistil, the lower part of which is the ovary, the part of a flower which contains the ovules, and is so named from _ovum_, an egg.

The stem part of the pistil is called the style and the top of it is the stigma.

Such simple words as I have given must be learned, else we cannot understand botanical descriptions, and if this page is studied whilst we have the flowers in our hands it will not be difficult to identify each separate organ; when these are once arranged on a card with the name of each part written beneath it, we shall have attained some very useful information ready for future study.

In the buttercup flower all the five petals are the same size and shape; therefore, like hundreds of other evenly-formed blossoms, it would be described as “regular”; but if we take a sweet-pea, balsam, or monkshood-flower and examine its separate petals, we shall find they vary very much in form, and they are known as “irregular” flowers.

The sweet-pea is a type of a large order of plants producing what are called butterfly-shaped flowers, and _papilio_ being Latin for a butterfly, they are therefore called papilionaceous flowers. If we learn clearly about the various parts of such a flower we shall henceforth be able to recognise it at a glance.

In the sweet-pea we find a broad petal at the back of the flower which is called the standard, beneath it are the two side petals called wings, and within them is the keel, so named because it is shaped like the bottom of a ship. Within the keel lie the stamens and pistil—the most important parts of the flower, and to protect them from injury the standard is so formed as to catch the wind like a sail and turn the blossom round so that this broad petal shelters the keel from rain.

In our next ramble out of doors it will be well to try and gather all the specimens we can find of this order of plants. If it be in summer or autumn we shall soon collect a handful of these butterfly-shaped flowers.

On a common we shall find broom, furze, restharrow, vetches, tares, trefoil, clover, saintfoin, and other plants. In the garden and greenhouse we shall see many more species belonging to this class.

Having shown the difference between a regular and irregular flower, we will now proceed to notice how irregularity is caused.

If we pull off one of the buttercup petals and look at the base of it, we shall see a small pouch which contains honey; it is called a nectary or honey gland, and the position of this gland has much to do with the shape of the flower.

As each petal of the buttercup has a nectary at its base it follows that, all the petals being the same size and shape, the flower is perfectly regular—like a small golden cup. Now in other flowers we shall find the nectary very large and confined to one petal or sepal only, and this results in the flower having an irregular shape. Gather a violet, examine and compare the petals; four of them will be found to be nearly alike, but the lower petal is much larger because it has grown into a tube (called a spur) to secrete honey, and I need hardly say that the honey is intended to attract the bees so that the flower may be enabled to produce fertile seed. The enlargement of the lower petal gives the flower an irregular shape, and the same thing happens in the monkshood and many other flowers, where both the petals and sepals are thrown out of shape to form nectaries. In the orchid family this influence may be traced to a wonderful degree. The contrivances for insuring the fertilisation of their flowers are so many and various that books of the greatest interest have been written on that subject alone.

In the flowers we have hitherto noticed, both stamens and pistils are found, the petals are coloured, honey-glands exist, and some specimens also possess a powerful scent.

Such flowers are obviously very attractive to insects, and on that account they are called by modern botanists, entomophilous, which long word means that they are beloved by insects.

In sharp contrast to these gay and conspicuous flowers we may observe the very simple catkins of the birch, _Betula alba_. If we examine a twig of this tree in spring, we shall find two very distinct kinds of flowers (or catkins, as tree-blossoms ought properly to be called), one a stiff green spike standing upright, and the other longer and of yellowish colour, always to be found hanging down.

The former consists of a number of scales arranged on a central stem, and in the axil of each scale is the little pistil, with its pointed and divided stigmas. This catkin, later on, becomes the fruit of the tree, and sheds out with every passing breeze its little winged fruits, which are carried far and wide and often sow themselves in rocky crevices, and appear able to grow and flourish with only a modicum of soil.

_Natural Size._ _Magnified._

BIRCH FRUIT.]

The pendulous catkin is very soft and loose, and on the inner surface of its scales we find the stamens, which in due time will shed from their anthers the fertilising pollen. Here then we see flowers which are not so attractive to insects, flowers in which the stamens and pistils are separated and developed in different catkins, and such flowers are termed monœcious, from _monos_, single, and _oikos_, a house.

The most interesting feature of these tree-blossoms is their fertilisation by the wind; the slightest puff of air liberates little clouds of pollen from the loose swinging anthers; these pollen grains become entangled in the upright catkins bearing the pistils, and the future seed thus becomes fruitful. There are many trees and plants which are thus fertilised by the agency of the wind, and they are termed by botanists _anemophilous_, from the Greek words _anemos_, wind, and _philos_, beloved by.

In the common bryony of the hedges, we get another example of a green inconspicuous flower. Gather a few sprays of this in early summer, taking care to keep the specimens of each plant separate. Take up one specimen and you will find each flower has a small green calyx, a minute corolla, and five little stamens; not one pistil can we find on the spray.

The flowers on the next spray look very similar, but in them there are no stamens, the centre of each flower being occupied by a small pistil, and thus we learn that there are two distinct sexes in the bryony plant, the one bearing only staminate flowers, and the other producing those bearing only pistils. Such plants are termed diœcious, from _di_, two, and _oikos_, a house.

One of the earliest spring flowers is the arum of the hedges, known to village children as “lords and ladies.” Accustomed as we are to bright-hued flowers if in our gardens and fields, it is somewhat difficult to recognise that the pale-green sheath of the arum is a flower at all. It consists of a beautifully-folded spathe or bract, curving over at the top, and if we remove that we find a central stalk bearing a number of little naked flowers, arranged in the order shown in the plate.

First, below the club-like apex, a few hairs tending downwards, then the anthers containing pollen, and below these the pistils with protruding stigmas. The whole stalk is termed a spadix.

The outer green spathe forms a kind of prison, into which flies are enticed by the somewhat fetid odour which is exhaled by the flower. The flies easily creep in past the circle of hairs, which, as they point downwards, do not prevent their entrance, but, once in, these hairs are like a _chevaux-de-frise_, and hinder the escape of the insects. The flies in all probability carry upon their wings pollen from some other arum flower, and in their efforts to escape they brush off this pollen upon the stigmas, which thus become fertilised. When this has taken place the stigmas throw out a sweet juice upon which the insects feed; the anthers now shed out their pollen, with which the flies become covered; the hairs meanwhile have withered, and thus the flies, having done their appointed work in fertilising the flower, are free to crawl out and perform the same office for some neighbouring plant.

We have not space to do more than allude to certain plants, whose flowers never open and are self-fertilised. The common violet, for instance produces, in addition to its well-known fragrant flowers, certain inconspicuous blossoms, hidden under the leaves and close to the root, very seldom noticed by any but botanists, and known to them as cleistogamic flowers; these are fertile, and always produce seed. Other such plants are the woodsorrel and sundews.

It is interesting to observe the various ways in which flowers are protected from browsing animals, snails, and caterpillars by thorns, spines, prickles, and spiny bracts. The teasel secretes water in the bracts around its stem, which prevents ants from ascending to the flowers, and in many plants we may see quantities of small insects caught by a sticky gum exuded from the leaves and twigs.

Many delicate plants entirely alter the position of their flowers in order to protect them from rain. On a sunny day the wood-anemone holds its little snowy cup so as to receive the full sunlight, but on a damp day every blossom is closed and held downwards. We may observe this in the poppy, the blue-anemone, and nearly all composite flowers.

These are merely hints scattered over a wide field of study, which some readers may like to follow out.

Objects to collect and examine:—Buttercup flowers, seed-vessel of wild-geranium, stonecrop growing on walls, flowers of bulbous plants, flowers of poinsettia, bougainvillia, salvia hormineum, arum. Examine various chrysanthemum flowers, sunflowers, asters and woodsorrel. Difference between hydrangea and poppy flowers, winter cherry (physalis); prepare flower dissections. Examine various cruciferous flowers and pea-shaped flowers, regular and irregular flowers, birch catkins, wild arum flowers, cleistogamous flowers, protection of flowers, position of flowers.

CHAPTER VII

_POLLINATION_

“When summer shines,
The bee transports the fertilising meal
From flower to flower, and even the breathing air
Wafts the rich prize to its appointed use.”

+Cowper.+