Part 9

For sepals, too, came from stamens. The plants made all these new forms out of the materials of their leaf buds and wrapped them all together into a flower bud; so when this opened, there were the parts all ready to go to work without any more shifting around.

The calyx was ready to protect, the corolla to call the bees and butterflies, the stamens to make pollen, the pistils to make ovules.

Sometimes flowers forget and go back to the old ways of doing things; and if we are lucky enough to find such a flower, we can see just how it happened.

Sometimes roses behave in this peculiar way, and the flower goes back to leaves.

I used to know a bush whose roses did that. The pistils were leafy and also the stamens, and sometimes a branch grew right out of the middle of a rose as it does out of a leaf bud. Of course it was a very ugly-looking thing, neither flower nor leaf, but it was very instructive.

What do you suppose double flowers are?

Very often they are only flowers whose stamens have changed into petals.

A double rose has fewer stamens than a single rose, and sometimes _all_ the stamens are changed, and the rose has not a grain of pollen to help itself with. What becomes of its seeds? It does not have any, as a rule. Where flowers become very double, the vitality goes to make petals instead of essential organs, as stamens and pistils are called, and such flowers often set no seeds.

Then how do they continue the life of the race?

Sometimes simply because somebody takes care of them. Almost always double flowers are cultivated ones. People take them and tend them, give them rich soil to grow in, water them, and, if necessary, keep them warm. Such plants seem to grow lazy and helpless, as rich people who pamper themselves a great deal always do. They have all they want without any effort of their own, and so they cease to be self-supporting; they cannot even raise their own children, but live and die seedless. Such plants, if left to themselves, would quickly die, as they would be crowded out by sturdier growths, or else they would change their habits at once and become good seed-setting, industrious plants once more, with a tendency to stop having double flowers.

There are one or two things about corollas that I am sure you would like to know. One is, how did the flowers manage to change stamens into corollas? Another is, how did they manage to give them such bright colors?

About corolla-making,—if you are determined to know that, you will have to take yourself off to that far-away time when there were no flowers. Then, in course of time, while changing about and trying to get fitted to their surroundings, the plants, as you know, rolled some of their leaves into pistils and stamens. But still they had no petals.

The pistils and stamens were flowers, however,—as much flowers as they would ever be, no matter how much corolla they might develop.

A corolla does not make a flower; by this time you know the important part of a flower is the pistil and stamens, and so, even to-day, some flowers, as the elms and some maples, have no petals at all. When such maples are in bloom, you will see gay fringes decorating the trees. This fringe is made of the long pedicels with the stamens at the end. The stamens swing in the breeze, and the pollen is blown to the stigmas which are often in flowers on different trees.

Now, as plants grew and adapted themselves to their surroundings, they produced more seeds than could by any chance find room in the earth to grow. So every little seed that fell had to fight its way with a host of other seeds and plants. A defective seed or a weak one would stand no chance at all. The others would crowd it out. We know how that is in a garden. The delicate flowers have to be helped or the strong weeds would kill them. We pull up the weeds and let the flowers have the whole garden to themselves. But in the woods and fields each plant has to take care of itself and struggle up as best it can.

This fight of the plants for a place to grow in is called the struggle for existence. Now, whatever would help a plant in the struggle for existence would, of course, be of great benefit to that plant. As we know, cross-fertilization is a very great help; it makes stronger and better seeds, and the plants whose seeds were regularly cross-fertilized would be the ones to survive.

Where pistils and stamens are forming, there is a great deal of nourishment brought to that part of the plant, and substances are being changed there. Very often sweet juices are present. Long ago when insects, in flying about, smelled these sweets they doubtless would go and eat them, and they would also eat the pollen. As they went from flower to flower looking for food, they would carry pollen sticking to their legs or bodies, and so would sometimes fertilize the flowers.

The seeds from such flowers would be strong and would have the best chance to survive. The plants that grew from these seeds would also inherit the tendency to secrete sweet juices near the flower.

In probing for sweets, the insect would irritate the parts it touched, and this would cause an extra flow of sap there and very likely the manufacture of more sweet juice; so the nectary came to be developed.

You can understand how this might be by recalling how the skin of your hand changes when you first try to do some new and hard work, like rowing a boat.

After you have rowed a little while your hand is blistered. The constant rubbing of the oar in one place has irritated it, just as you can imagine the tongues of the insects rubbing against the delicate flower tissue would irritate it. Wherever a place on the skin is irritated, the blood flows to that spot; and so in the plant, where it is irritated, there will likely be a collection of sap. After the blood has flowed to the place on your hand which was rubbed by the oar, the spot becomes red and inflamed and pains you, and finally the skin separates in the form of a blister and a new skin forms underneath; and if you keep on rowing, your hand does not keep on blistering, but actually makes a new kind of skin to protect the rubbed places, and what we call a “callous” or hard spot is formed. The skin is many times thicker here than elsewhere, and was formed on purpose to protect the place. So we can understand how irritation might change a plant organ and in time form a nectary.

But how about petals, you are asking. Well, imagine yourself in those old times when plants made their first flowers out of pistils and stamens only.

These primitive flowers were probably not very showy. Primitive flowers means _first_ flowers,—flowers that lived way back in the beginning of plant life.

They had no petals, but they secreted juices which the insects liked. Those early insects were queer fellows, too, not very much like our insects, except that they were fond of sweets and liked to eat the tender parts of the flowers, just as our insects do to-day. They ate nectar when they could find it and did not disdain pollen, which, it is to be feared, they sometimes ate, anther and all; and, what is worse, they in all probability frequently dined on pistil, which was very bad for the plant.

Now imagine one strong plant secreting a good deal of nectar. The insects would be likely to eat this and let the pollen and pistil alone, only in getting to the nectar, they would be apt to dust the pistil with pollen from another plant which they had been visiting and would also brush off some pollen against their bodies.

Thus the strong plant with the abundant nectar would be cross-fertilized and would keep its pistil unharmed. It would be very likely to develop good strong seeds that would grow and again bear strong flowers with plenty of nectar. Now, remember the essential organs—that is, stamens and pistil—seem to find it a little easier to change than other parts of the plant; so it would not be surprising if in time some of the stamens were to become different. You see, the insects in visiting the flowers would irritate them more or less walking over them and clinging to them, and they would be likely to undergo change for this reason; and if it happened that in some flower a row of stamens got too full of sap to know what to do with themselves and so spread out a little broader and more leaf-like and kept their yellow stamen color or bleached-out white, that flower would be seen far and near and the insects would go straight to it, for insects have the sharpest kind of eyes for seeing bright colors a long way off. You see what would happen; all the flowers whose stamens had done so would be abundantly cross-fertilized,—that is, all their seeds would get fresh pollen from another strong plant, and the plants growing from these seeds would inherit the tendency of their parents to form petal-like parts from some of the stamens. The flower could well afford to lose part of its stamens for this purpose. Of course as time went on, these stamens, which were half petals, might develop more and more in the direction of signals,—that is, might become more and more perfect petals, finally losing all trace of their old life as stamens.

Of course no one can say that is just the way it came about, but it is likely that in some such way it happened, for there are proofs of it which you may like to read when you grow older.

So, you see, flowers _are_ nothing but leaves after all,—very much changed leaves, to be sure, but yet just leaves.

Sometimes when plants and animals have changed into a new form, they change back again. We know some plants which once had petals but which have again lost their petals and gone back to a form which has no petals. Such backward changes we call retrogression, and it is sometimes difficult to find out whether a flower with no petals is a primitive form which for some reason has not changed or whether it is one which has changed and gone back again. Usually, though, we can find traces of petals and sepals in flowers which have retrogressed.

You see, a flower depends upon its surroundings for its shape. If its surroundings (and of course this includes its insect visitors) are such as to favor its growth in the line of petals, it does so. But if for some reason it becomes easier for it to grow and be fertilized in some other way, perhaps by making abundance of light pollen which is blown by the wind, as in the maple trees, then it may gradually lose its petals, as it depends less and less on insects and more and more on the wind for cross-fertilization. Nothing in life stands still; it is always moving,—going on or going back. And this, we know, is just the same in human life.

We cannot stand still; we must keep growing wiser and stronger and better, or else we must do the opposite.

SIGNS OF OTHER TIMES.

In the beginning flowers seem to have had their petals all separate from each other. Some do still, and these we call polypetalous, because “poly-” means many, and they have many petals. But other flowers, like our morning-glory, have no separate petals; all are grown together into a tube with a bright border.

But this tube and border tell us a little story if we are able to hear it.

They tell us of the time when the morning-glory had several petals. More than this, they tell us just how many it had. If we were to guess we should probably say five, because it seems so fond of the number five, with its five nectaries, five nectar guides, five stamens, and five sepals.

If we guessed five we should guess just right. There is no doubt but that once upon a time the plants from which our morning-glories are descended had five separate petals. The morning-glories themselves manage it differently now, but it took them a long time to do it. They were working away, long before the great pyramids of Egypt were built, to get their five petals united into one piece. But it is done, and they have learned how to twist the flower up tightly in the bud and then unroll it in all its glory.

They never have five petals now, but they still bear traces of it.

Look at the little notch on the border, halfway between two nectar guides. Does that tell us anything?

Count the notches. Five, you see.

Look at the line that runs from the notch down to the bottom of the flower.

The corolla looks as though it had been folded along those lines. You can easily see five long creases ending in a notch. The flower is folded along these lines in the bud, but we think the lines have yet another meaning.

Carefully tear the corolla down the lines; you see, a very little pressure does it. Now we have the corolla in five parts, like five petals, only it is so weak it can no longer hold itself up. Once upon a time we think it grew this way, with five separate petals, only the petals stood up then, for they must have been stiffer and perhaps were not so long. It was long, long ago, oh, very long ago, that it had its five petals. Then the edges of the petals began to grow together, and they kept on doing this until, in course of time, the whole length of each petal had grown fast to the next one, all except that little tiny spot where the notch is.

We are glad our morning-glory kept this little notch and the line where the sides of the petals grew together, for that is what tells us the story of long, long ago when all the petals were separate.

When finally they were grown together, the corolla did not need to be so stiff, for its shape helped to make it firm, and then it no longer used good material to make stiffening for the petals, for that would have been a waste of plant sap, and plants do not like to waste materials. When they find they can get along without something they have been used to having, they stop making it. Life is too short and too precious to waste a bit of it. Our flower only kept the stiffening in the corolla along the paths where it wished the bees to go to its honey cups and where, when folded, it could best protect the bud.

The morning-glory, you see, is as wise as it is beautiful.

WHY ARE THE FLOWERS SO LARGE AND BRIGHT?

Why are the flowers so large and bright?

We cannot say that they were always so. It is probable they were not. But good Mother Nature has watched over them as they came upon the earth, and she has lovingly made them so large and bright.

How could she do this? Let us see. Here is a tangle of plants. They all bear flowers and all set seeds. Some are stronger and more beautiful than others. The seeds fall to the ground. Those from strong and beautiful plants are larger and stronger than the others. After a while the seeds sprout. Not all do this, however. The very weakest do not sprout. Dear Mother Nature has other work for them. “You are not suited to struggle in the earth with the strong seeds, dears,” she whispers and lays them to rest. They do not wake up; the materials in them change. These materials let go of each other; they depart from the seed; some as gases float off in the air; others as minerals sink in the earth. The gases and the minerals are not lost. They join some other plant and help to make it strong.

“It is better to help another than to try to grow yourselves,” Mother Nature whispers to these little seeds that could not sprout. And they are happy. They are glad to change into gases and minerals and help another plant to grow.

Many of the seeds sprout, but not all grow up and blossom. There is not room in the earth for all the seeds to grow; there is not food enough in the air to feed so many. Mother Nature with her kind eye looks over the growing plants.

She smiles and shakes her head at those trying to grow in shady places.

“No, dears,” she whispers, “there is other work for you to do.” Then the shaded seedlings do not try any more to grow into plants. They give up the materials they have collected to the little brothers and sisters who have started in the good ground and the sunlight.

They fade away, but they are happy, for they, too, are doing their work. The materials in them let go of each other. They change into gases and float off in the air, or to minerals and other substances and sink to the ground. These gases and solid substances pass into other plants and help make them strong.

“It is better to help another than to do poor work alone, dears,” Mother Nature whispers, as she lays them to rest.

Then she visits all the weak plants, and all those in poor soil or in too much light or too much shade, and lays them to rest. Their materials go to nourish the strong plants, who are doing good work in the world and growing in beauty. Not all the plants that live to blossom are good alike. Some are better than others, but Mother Nature lets them grow if they are strong enough and can find food. At last the blooming comes. The flowers do their best. The strong ones make large, bright flowers full of color and full of sweetness. Mother Nature smiles at them and is pleased. The weaker flowers do their best; they are not so bright nor so large. Mother Nature smiles at them, for she loves them, too, and she will tell them what to do. The bees come and fly to the brighter flowers; they have rich, abundant pollen and rich nectar. The bees know this; they do not care so much for the duller, smaller flowers.

When the bees do not come, Mother Nature whispers to the little flowers, “Never mind, dears, there is work for you to do.” So they are happy, though their ovules get no pollen and they set no seeds. They are happy to do the work dear Mother Nature has for them to do.

The strong flowers set their seeds; they are strong, and they have been well fertilized. The weak flowers set few seeds; they are not strong to make many seeds, and they have not been well fertilized. So year by year and century by century Mother Nature watches her plants and encourages the strong to grow and helps the weak to find other work.

And this is why the flowers are so bright.

Mother Nature selects those that are to grow and blossom and sends the rest to help them. This is what we call natural selection, and this is what makes the earth so beautiful. Only the best continue to grow; the others are glad to help them.

HOW MOTHER NATURE MAKES NEW FLOWERS.

Once upon a time there lived a little plant in a marshy place. We will call it Primus, not because that was the very first form of the plant, for it was not, but because that was its form when we first saw it.

It had five small yellow petals, five small stamens, and an ovary.

When its seeds were ripe, along came a great wind and blew them away from the marsh upon the dry land at the edge.

Poor little seeds, they were out of their familiar wet marsh and they could not grow. But they did their best. Some of them managed to sprout, but soon they found the earth too dry and the sun too hot; so they said, “We will turn to other work; we will help the other plants and not try to grow ourselves.”

So they changed into gases and minerals and other substances. But a few of the seeds continued to grow.

They blossomed and bore seeds, but they were not just like the plants in the marsh. Mother Nature had helped them get a tougher skin and taught them how to shut tightly their pores in dry weather, so that the water within them could not escape.

You see, they were already different from their parents, though you might not have noticed it if you had seen them, the difference was so slight. The seeds of these new plants sprouted the next season. They did not have a hard time to grow. They knew just what to do, and the best and strongest of them grew a few hairs to help cover up the pores, so the water would not go out too fast.

It happened to be a very hot, dry season, and all the plants but these hairy ones stopped growing. They changed into gases and minerals and other substances to help the other plants. The hairy people got through the dry season very well. They set a good many seeds, and these seeds sprouted. The new plants remembered about the hairs and had plenty of them. Some were covered all over with a soft down.

And it was well they were, for it was a _very_ hot, dry season, and all but the downy ones stopped growing and changed into minerals and gases and other substances to help the others. The seeds of the downy plants blew far over the dry land, far away from the marsh; but they had learned to live in the dry soil, and if you had found these downy people, you would hardly have known they were descended from the smooth, juicy, large-leaved marsh plants. Their stems were hard and tough and their leaves stiff and small. We can no longer call them Primus, they are so changed.

Let us call them Secundus. Secundus had small yellow flowers, like the marsh plants it was descended from. But one day some of the seeds of Secundus blew into the edge of a wood where the soil was rich and the air damp. This just suited the Secundus seeds, and they grew into very thrifty plants indeed. They had so much sap and grew so luxuriantly that their petals were twice as large as was usual with Secundus petals. These fine showy flowers also possessed a great deal of nectar, they had so much sap. Of course the bees came to them, and they were well fertilized. They set many seeds. The next year these strong seeds were able to grow even when their neighbors were not, and the plants that came from these seeds also had large showy flowers.

These stronger plants held their own, you may be sure, and at last there was more of them than of the small-flowered plants. It was well for them this was so, for there came several bad seasons when nothing was just right for these plants. It was cold and stormy, and only the very strongest lived through it. But _they_ managed to survive, and their flowers were large and showy.

All the weaker plants with smaller flowers were killed out, and only these large-flowered ones remained. They were _very_ different from their ancestors the marsh plants, and we shall have to call them Tertius.

One day some of the seeds of Tertius were blown into a new kind of soil; they sucked up the juices of this new soil, and lo! some of their flowers opened white instead of yellow. It so happened that the white-flowered plants were stronger than the others. The bees liked them, too; for, being so strong and full of sap, they made plenty of honey. So these white-flowered ones increased in numbers very greatly. At last only the white ones could be found; the yellow ones had gradually given way before them until no yellow ones were left.

So we will call the white-flowered people Quartus.

Quartus lived a long time, each year bearing seeds, the strongest and best of which grew up and bore flowers.

One day some of Quartus’ seeds were blown into a hot, sandy place; this almost killed them, but some of them managed to grow.

Their leaves were smaller and stiffer than ever before, but they had a great many of them, and their flowers were large and white. They grew to like the sandy soil, and what they got from it changed their sap in some way so their petals were delicately tinged with pink. The bees liked these pink flowers; perhaps their honey was a little richer; perhaps they could see them better. However that may be, the bees almost deserted the white-blossomed plants and visited the pink ones. So the white flowers set few seeds and the pink flowers many. When the seeds sprouted, the pink ones were the strongest, because in their change of color there was somehow added a change in strength; they were stronger than the white flowers. They grew fast and took the materials from the earth and the air; and when the white flowers saw this, they said, “It is their turn now,” so they changed into gases and minerals and other things and helped the pink flowers to grow.