CHAPTER XV.

FLOWERS

If you have ever noticed a pea-flower fading, you will have seen that from its heart there grows a little green pea pod which ripens till there are full-grown peas in it (~see~ fig. 80); and a yellow dandelion flower turns in the end to a white puff ball which scatters a hundred floating fruits. In fact, almost all flowers which have not been spoiled by the gardeners and “over-cultivated” leave in their place when they die fruits and seeds in some form or other. ~This gives us the key to the secret of the structure of the flowers themselves.~ =They are the forerunners of the fruits=, ~containing living seed, and their structure and all their parts are adapted in some way to help in the formation of fruit~. Now let us examine the flowers, never forgetting that fact.

Let us choose, for example, a harebell. On the outside we find five separate green parts, and if we examine a bud which has not yet opened we shall find that these fold quite tightly over the inner portions of the flower and protect them, as they do in the rose and in almost all flowers (~see~ fig. 69). In this they correspond to some extent to the bud scales, and their special work is that of ~protection~. In all harebells and roses there are five of these parts, but in the wallflower you will find only four, and in poppies two, and so on. There are different numbers of them in the different kinds of flowers. They are also of different shapes and sizes; sometimes each of the five parts is free, and sometimes they are all joined up together to form a true cup, as in the primrose (~see~ fig. 72). These outer green protective parts have a special name, and are called the ~calyx~ or cup, while each of the separate parts which makes the cup is called a ~sepal~.

Directly within the calyx we come to the parts which are generally bright and prettily coloured, and which give the chief beauty to the flower. In the harebell which we are examining these parts are joined up to form a bell, but in the rose they are each separate (~see~ fig. 71). In both harebell and rose we find five of these parts, and the same number in the primrose, where you will find that they are joined up at the base to form a long, narrow tube, and then spread out separately like those of a rose. Both in the harebell and primrose, where they are joined up, we can tell the number of parts which go to make the whole bell or tube (and this is nearly always the case in bell flowers), while, of course, where the parts are free it is quite easy to count them, and we find that for each kind of flower their number is always fixed. For example, we find five in the harebell, rose, primrose, and many others, four in the poppy, wallflower, cress, and so on. These parts are called the ~petals~, and in almost all flowers you will find that they are bright and pretty, and stand out from the surrounding green leaves, so that they are easily seen. When the cups or bells hang down they may protect the parts within from the rain, but that is not generally their chief work. The ~first duty of the petals is to be attractive~. You will understand better why this is so after we have gone further into the flower.

Within the petals, and, in most cases, lying at the base of the bell, you find several yellowish dusty sacs, on fine thread-like stalks. In most flowers they are all free from each other and from the petals, but in the primrose they are fastened to the tube of the petals (~see~ fig. 72). In some flowers you will find a great many of these, as you do in the wild rose (~see~ fig. 71) and the poppy, where there are so many that you can hardly count them. In other flowers there are very few; for example, there are only two in the blue speedwell (~see~ fig. 73). In most flowers the single ~stamens~, as they are called, are very much alike in their structure, and they all have the same work to do. Look at these structures in a tulip or lily, where they are very big, and carefully pull one off and examine it (fig. 74). You will find that it consists of a stalk which we call the ~filament~, with two long sacs at the tip which hold the yellow dust, and which we call the ~anthers~. If you examine a fully blown flower of the tulip or lily, you will find that the sacs split open right down their length and let out a fine yellow powder. ~This powder is the important thing about the stamens, and is called the~ =pollen=. In all stamens you will find the anthers or pollen sacs, while the stalk, which is less important, is not always developed. Sometimes the sacs split right open like those in the lilies, but there are other ways of opening; as for instance, in the rhododendron you will see a little round hole at the tip of each anther, which lets the pollen shake out like pepper out of a pepper-pot.

~Now we have come to the heart of the flower, and find there the most important thing in it.~ Examine a sweet pea, for example, and you will find in the middle of the flower a tiny green structure very like a pea pod, with a little sticky knob at the tip. In the heart of a tulip you will find a long green box with a sticky, three-cornered knob at the top (fig. 75), while in a buttercup there are a number of these structures instead of one (~see~ fig. 76 ~s~), each of which has very much the appearance of a little pea-pod. Open the pea-pod, or the box of the tulip, and you will find within it a number of very small balls of a clear green colour. These are the young structures which will become seeds when they are older, and they are the most important things in the flower. The green box which protects them is called the ~carpel~ in the case of the pea-pod, where there is one space in it. In the tulip you will find that the box is divided into three compartments, and each of these is called a carpel (~see~ fig. 77). You may think of the tulip carpels as being the same thing as three pea-pods joined very tightly together. Some flowers have only one carpel; others have three or five joined up like those of the tulip, while others like those of the buttercup have a very large number of single separate carpels.

In the pea, tulip, buttercup, and many others, the carpels are in the centre of the flower, above the petals, and attached to the swollen end of the flower stalk, which is called the ~receptacle~, as in fig. 76 R. Other flowers have the receptacle hollowed out like a cup or goblet, and the carpels sunk right in it. When this is the case, we generally find that the sepals and petals lie above the carpels and not below them, as in fig. 78. This is also the case in the rose, where in fig. 70 flower B shows clearly the swollen part below the bud, which is the hollowed receptacle containing the carpels, and the same is true of the harebell (~see~ fig. 69) and many flowers.

What can be the use of the sticky tip that we found on the carpels? Examine the tip of the carpel of a lily which is well open, and you will very likely find some of the yellow pollen sticking to its surface. It is a curious fact that the little structures within the carpels which will become seeds cannot ripen into true seeds unless they are waked up to growth by the pollen grains. ~The sticky tip of the carpels~ (or ~stigma~, as it is called) ~catches the pollen grains and holds them; then they grow down into the carpels and carry with them the nuclei~ (see p. 92) ~that enter the undeveloped seeds. These stir the cells to divide, and after many divisions the embryos are formed and the seeds ripen.~ Sometimes the stigma has a long stalk which places it in a good position to catch the pollen grains. This stalk is called the ~style~, and is to be found in many flowers (~see~ fig. 72).

The pollen dust is fine and light, and may be carried by the wind on to the stigma, as it sometimes is in poppies, and always is in pine-trees; but this is rather a wasteful way, because the wind blows so irregularly that very much pollen is lost and never reaches the stigma. In order to save some of this loss, and ~to make the pollinating more certain~, flowers have arranged their parts so as to make use of the help of insects. You know that very many flowers have sweet honey in them which the bees like, and come to collect, going from flower to flower to do so. When the bee settles on the flower it gets covered with the pollen dust, and then when it goes to the next flower and walks over it, it is almost sure to leave behind it some of the pollen sticking on the stigma. Of course, in this way also some pollen is lost, but insects are far more reliable than the wind. We now see the use of the bright coloured petals; they help to attract the bees to the flower. The flowers have made the bees and other insects their special carriers of pollen, and they pay the insect with honey, and some of the surplus pollen. Bees generally go from flower to flower of the same kind on any one day’s journey, so that the flowers get pollen from others of their own kind. This is important, for “foreign pollen” (as the pollen from quite different kinds of flowers is called) does not help the young seeds at all.

We have now found a use for all the parts of the flower.

There are many special things about flowers which we must leave till later on, but we may just notice now how some are regular, like the primrose, rose, poppy, and so on, which are after the pattern of a circle, and appear the same from whichever side you look. Others, like the violet, larkspur, or sweet pea, are not regular, but have only two sides alike. This difference is very often due to some special structure of the flower in relation to the insects which visit it, and if you examine and compare the two-sided with the circular flowers you will generally find that the two-sided flowers are the more complicated. Some of them become very complicated indeed, like the orchids, which have such strange flowers, and in which the relation between the insects and the flower has become very special.

We must leave these more complicated cases till Chapter XXII., and come back to ~the simple important facts about the work which all flowers have to do~. =They must make sure that in some way or other, seeds are formed for the plant.= If the flower does not do this, then it is not doing the work for which it was made.

You will find a number of flowers in gardens which do not do their work properly, and very often have no seeds at all, but they are specially cultivated by gardeners to do other things. For the study of the true structures of flowers, it is generally better to examine wild flowers instead of garden ones, which are often much altered by the rather unnatural conditions in which they are made to live.