The garden of the world

Front matter

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II Publishers Note

This book presents in popular form the present state of science. It has been reviewed by a specialist in this field of knowledge. An excerpt from his review follows:

"/ believe that'The Garden of the World* will go far toward satisfy¬ ing the child's natural curiosity about plants. The contents are well chosen and attractively presented ”

“Yon pretty daughters of the Earth and Sun' u

THE SHEPHERD TO THE FLOWERS

Sir Walter Raleigh

By

Janet McGill

THOMAS S. ROCKWELL COMPANY Chicago 1930

*

1.0

Copyright, 1930, by

THOMAS S. ROCKWELL COMPANY

CHICAGO

Printed in United States of America

©CIA

28671

Contents

I Plants without Seeds ii

What is the green scum on water? What are the smallest plants? What causes bread to mold? What is moss? What are ferns?

II Friends and Enemies 26

Chapter II Why are sun¬ flowers yellow?

W E ENJOY the brilliant colors of many flowers, but the plant is not trying to attract us when it puts on its golden petals. It is attracting the bees and wasps who have an eye for color also. The sunflower is anxious for the bees and wasps to see it and to visit it, for unless they do, it may never have any seeds.

Every plant has three objects in life: to live, to grow, and to produce other plants like itself to carry on its life when this plant has died. Most of our common plants accomplish this third object by means of seeds. You all know the hard, dry seeds which we plant in the garden, but perhaps you have not paid so much attention to the young seeds. The seeds are born in the flowers. If you pull the center of a sunflower early in the summer, you will see the baby seeds, which are white and milky. At the end of August or early in September, you will find that they have become hard and dry and much darker in color. Now a curious thing about seeds is that they never become full

The seeds will never become full grown unless they have been pollinated

grown so that they can be planted unless they have been pollinated. That is what makes the difference between the baby seeds and the ripe ones which grow into new flowers.

Pollen is the yellow powder that comes off on your fingers if you rub them across a flower. The part of the flower that holds the baby seeds is called the pistil . It usually has a sticky point called the stigma . The pollen must be put on to this stigma in order for it to get to the young seed. It might just happen to fall there, or the wind might blow it, but the sunflower can¬ not depend on such uncertain methods. If a bee, however, should walk across the flower, the pollen would stick to his hairy body, and then, when he rubbed against the sticky point of the stigma, it would be rubbed off again. There are so many stigmas close together on one sun¬ flower that one bee would pollinate a great many. This, then, is the very best way for the sunflower to have its seeds ripen, so it tries in every way to make itself attractive to bees and wasps. But the insects do not pollinate the flower just to help it out. They want some¬ thing for themselves. What they are after is the pollen. They eat it and feed it to their young. The sunflower has a great deal more pollen than it needs, so the insects may carry off all they wish without hurting the flower. When a bee is out hunting for pollen, he goes to the plant that he sees first. Yellow is a very noticeable color, so the sunflower puts on big yellow petals to make itself as gay and bright as possible. It is necessary for the plant’s future life that the bee sees it, and the bee usually does. The sunflower also puts its yellow flowers on the top of a tall straight stem to make them tower above all the other flowers in the garden. This helps the bee to find it.

The sunflower is not the only flower that in¬ vites insect visitors by its gay coloring. Nearly all bright colored blossoms have the same object; the sweet peas, the clover, the daisies, the iris, and the phlox are a few of them. The sweet smelling flowers, too, give off their fra¬ grant odors so that the insects which do not see very well find them by the sense of smell.

We do not know exactly why the sunflower is yellow rather than some other color nor what causes the difference in shades among the

How do plants club together?

flowers. The color is made by a substance called anthocyan (pronounced an-tho-si-an), but men who study flowers do not know a great deal about this substance.

A fact which we must never forget for a moment when we are thinking about flowers is that the flower is only interested in attracting insects to itself so that its seeds may be polli¬ nated. Large flowers like the water lily are easily seen, and they can get along by them¬ selves. Small flowers, however, are often hard to see; therefore, we often see them growing in groups. Lilacs are groups of flowers, and you know how easily seen they are. The bridalwreath which blooms on bushes in our gardens in early spring is another example. So is the hyacinth. You can see the separate small flowers very readily. This group arrangement has two advantages—the flower can be seen better, and the insect can pollinate a large number of seeds at one time.

Some flowers are so small that we think of the whole group as just one flower. Clover is an example of this kind. Did you ever notice that one clover blossom is made of dozens of tiny flowers? If you haven’t, pull one apart the next time you have a chance and you will see them. Bees love clover because of its sweet nec¬ tar, but they could never find it if these tiny flowers grew by themselves. Because they have clubbed together into a good-sized group, the bee has no trouble whatever in finding them.

There is another family which has even smaller flowers. These flowers are so tiny that most people never think of them at all but say that a daisy is a flower, or that a dandelion is a flower. It is more correct to say, “A daisy is a great many flowers growing on one head.” If you take a daisy apart, you will find two kinds of flowers. Each one of the outside petals is nearly a complete flower all by itself. It has one big petal and a pistil, which is the part that holds the baby seed. It usually does not have any stamens; and so it has to get pollen from other flowers. The inside, or heart, of the daisy has hundreds of tiny flowers. They do not

Clover is made of many blossoms

3 2 have big petals, and are so small and yellow that many people think they are just stamens. When they are magnified, however, each is seen to be a tube of small petals, containing a pistil and some stamens. All of the parts needed to pollinate the seeds are there. Try to imagine, though, what a hard time such a little flower would have growing by itself. A bee would never see it, for it is no bigger than a bee’s leg.

The plant put all these small flowers on one big head which is bright and showy. The two kinds of flowers that make a daisy have their own separate work to do. The outside flowers with the large petals are called “ray flowers” because they stand out like the rays of the sun. The smaller, inside ones are called “disk flowers,” because they grow on a round, flat disk. The ray flowers are the most attractive. They tell the bees that here is a blossom with pollen and nectar for them. The disk flowers are the workers. They produce the seeds. The ray flowers are able to have seeds, but usually they do not.

The dandelion is another plant which has a head made up of many flowers. You can tell how many flowers there have been when the seeds are ripe and ready to blow away. Every

The clover, dandelion, daisy, and many other common flowers are really many flowers in one

seed stands for a flower. Sometimes there are as many as two hundred flowers on the head of one dandelion.

Plants which have heads holding many small flowers belong to the Composite family. Many

Why do flowers open and close?

of our commonest flowers belong to this family. Besides the daisies and dandelions, there are the sunflowers, brown-eyed susans, dahlias, chrys¬ anthemums, and thistles.

Flowers close to keep out the rain, to keep warm, and to keep unwelcome insects away from their pollen. They stay open during the business hours of the insects they favor. If bees and butterflies are wanted, the flower is open in the daytime when these insects are flying. It closes at night to protect its nectar from the rain and dew. The flowers which prefer moths, however, are open at night and closed in the daytime because moths fly at night.

About four o’clock in the afternoon, the small flowers of the white honeysuckle begin to open, and the sweet fragrance becomes very strong. Soon the sphinx moth, attracted by the perfume, begins to hover over the blossoms. It is a large moth and resembles a humming bird when flying. It has a long tongue which it carries rolled up. At each honeysuckle this tongue is unrolled and thrust deep into the flower for a long drink of nectar. At the same time the moth dusts off onto its body some of the pollen, which it carries to the next blossom. It takes a great many honeysuckles to satisfy a thirsty sphinx moth. It flies about all night, guided by the perfume of the flowers, and by their white color.

White shows up much more plainly at night than red or other colors. That is why more white flowers than any other color smell sweet. They are designed to attract night flying insects. Sometimes the moths do not get to all the flowers before morning. The honeysuckles that have been pollinated turn yellow and close as a sign that they do not need any more visitors. The ones which have not been visited by the moths stay open for a time in the morning to let the bees and the butterflies do what they can. They come around anyway to get what is left. If the night has been clear and calm, they will not find much nectar or pollen because the moths have taken it all, but if the night was stormy, the moths would have had to find shelter from the wind and rain, and the bees may have a feast.

The Jimson weed also waits for four o’clock to entertain the sphinx moth because its nectar tubes are too long and narrow for any other insect to reach. Sometimes it opens early and the bees come and take the pollen.

The beautiful evening primrose stays closed all day to protect its pollen from bees and flies, for it is also waiting for the sphinx moth. If the moth misses a flower, that flower stays open in the morning until a bumblebee visits it. It must be pollinated at once because its petals last only one day.

There is a family of blossoms called the Catchflies. The night blooming catchfly is a pale pink and has a sweet perfume to attract the moths. The day blooming catchfly has no odor at all, but has bright colors to guide the butterflies which fly by day.

On the whole, colored flowers bloom by day and close at night, while white flowers open at night and have the sweetest perfume. There are exceptions, to be sure, but this is the general rule which the flowers follow.

Have you ever noticed how many red flowers have their nectar hidden in deep slender pockets? If you want to suck the nectar, you must bite off the end of a tube and get it from the bottom for, of course, your tongue is too thick to get into the narrow opening. The bumble-bee’s tongue is narrow but not long enough. At least a dozen red colored flowers are made this way: the trumpet flower, the coral honey-suckle, the red and yellow columbine, jewel weed, bee balm, gladiolus, canna, nastur¬ tium, and salvia are some of them.

Red seems to be the favorite color of the hum¬ ming bird. These red flowers are saving their nectar for him. His long, sharp bill is just the right size and shape to fit into their nectar tubes. They bloom later in the summer than the blue and yellow flowers as a rule, because the humming bird does not come as early as the bees. To be sure, many of the flowers wait in vain, because humming birds are not very

Why do so many red -flowers have long narrow tubes?

common. Often times not one comes to a garden in a whole season. These red flowers would not get their seeds pollinated if the bees

The humming-bird's bill is the right shape to reach the nectar of certain flowers and butterflies did not help them out. These insects cannot get to the nectar, but they are never tired of trying, and there is plenty of pollen to reward them.

Sometimes the humming birds do come, however. If they are anywhere in the neigh¬ borhood, a garden with red flowers is sure to attract them. Some people plant trumpet vine and coral honeysuckle just to entice them. If they do come they dash from one flower to an¬ other in a perfect frenzy of joy. Their little wings beat so fast they seem to be just a blur in the air. Their sharp little beaks find the nectar in a second and drain every drop. They do not care for pollen as the bees do, but, of course, it sticks to them anyway, and they carry it to other flowers to pollinate them.

Crawling insects, like ants, usually are enemies to plants, while flying insects, like bees and wasps, are friends. A plant’s problem is to make the flying insects welcome and at the same time keep out the crawlers. The crawl¬ ers are enemies because they eat the pollen and drink the nectar but do not carry the pollen to the other flowers. It is easy to see that by the time an ant crawled all the way down the stem of a rose-bush and up another stem to another rose, the little bit of pollen that had clung to him would be brushed off. A bee, on the other hand, flies in the air from one flower to another

How do plants protect them¬ selves?

4 o so quickly that she cannot help but carry the pollen. It is the flower’s business to see that its pollen is carried to another flower, and nature provides a means to prevent any insect that in¬ terferes with that business from taking the pollen and nectar. If ants get into the flower first, there will be no pollen left for the bees and butterflies; so the ants must be kept out.

Some flowers, like roses, have many fine hairs along their stems that keep an ant from crawl¬ ing up. As she goes up the hairs keep getting thicker and thicker. They are like a forest to her; so she gives up. The hairs near the top are smeared with a gummy juice which hold her legs. It is just about impossible for an ant to get to a rose.

Milkweed juice is useful against ants, too. The skin of a milkweed stem is very thin. As the ant crawls up, her sharp feet cut through the thin skin and start the milky juice to flow¬ ing. Her feet become wet and tangled. If she is wise she will drop off immediately while she still can. If she keeps on trying to get up, the juice hardens and holds her so fast that she can never get away.

The wild pink punishes crawling insects who try to steal nectar by catching them in a sticky juice smeared high on their stems. It holds them as fast as fly paper does. Perhaps you have noticed certain weeds that made your fingers sticky when you picked them. This is the reason for that stickiness.

Some plants must protect themselves from ^ cattle who would eat their leaves before the season’s work is done. Roses and nearly all g plants of the Rose family have sharp thorns that give a sharp prick to any cow who tries to r take a mouthful. Wild parsnip which grows in the fields has a sour juice that causes the cattle to leave it alone. Some weeds have poisonous ^ leaves that make the cattle sick or kill them, if ^ eaten. Cattle soon learn to leave these plants alone and not to molest them.

Did you ever look inside of a burr? If cut across with a sharp knife, the seeds are found inside. The parent plant must have those seeds

Roses protect them¬ selves from crawlers

4 2 planted somewhere so that they can grow. The burdock, a plant that produces burrs, usually Why do burrs grows in thick patches. The space is crowded stiC k? with plants, and there isn’t much space for new

ones. The plant provides that its offspring gets far away and starts life in a new place,

The many different \inds of burrs have just one purpose—to be carried somewhere where there is not so much struggle for light and ground space and moisture. Its way of accomplishing this is to have little hooks on its seed pods. When a boy and his dog run through the prairie, some of the little burrs hook onto the boy’s stockings, and others catch on the dog’s hair. Later on the boy pulls the burrs off. Perhaps he will pull them off the dog too. If he doesn’t, the dog will have to bite them off, for they are sure to bother him. If the burrs happen to drop on the ground in a good place, they will take root and begin to grow, not right away, of course, but the next spring. If they are taken off in the house or drop on the side¬ walk, they are lost. The parent plant makes provision for many of its seeds being lost; so it produces a great many more than ever can grow. That is why each burdock plant has such big bunches of burrs.

The burdock is not the only plant that sends out its seeds in this way. There is the cocklebur. That is the plant with the good-sized burr which has a great many rather fine spikes. The burdock burr is smaller, with a few heavier, sharp-pointed hooks. The cocklebur is the kind that children often put together in big

Burrs travel a long way bunches or even use in modeling doll furniture and crude little figures. Another common plant with prickly seeds is the Spanish Needle. It has a single seed with two sharp points that are hooked. Sometimes one person will have as many as a hundred of them sticking to him at one time. The wild animals help distribute these seeds even more than people or dogs. They live in the places where these wild plants grow and they can carry an enormous number of burrs in their shaggy coats. Sometimes an animal, such as a squirrel or rabbit, or even a fox, will carry them for a long distance before he can get rid of them. In this way the new plant has a chance to find a good growing place, far from home.

And so burrs stick so that the seeds which they hold may be carried away from their parent plant to a new place which will be a good one for the new plant to make a start.

Chapter III

V INES climb in order to get their leaves into a better place in the sunlight. They have many ways of getting up from the ground. Some vines twine their stems about a support such as a fence rail, a stick, a bush, or a tree. A curious thing about these twining plants is that they always twist in the same direction. The hop vine winds from right to left, or with the sun. The morning glory always goes against the sun, or from left to right.

The cucumber and grape vine have tendrils. These look like short stems, but they do not have leaves. The ends of the tendrils are hooked, and they coil when they strike a sup¬ port. Sometimes a real stem acts as a tendril. It curls about a support and then continues on its way, bearing leaves as it goes. The Boston

How do plants climb?

4 6 ivy has tendrils also, but at their tips the tendrils have sensitive disks which give off a sticky juice when rubbed against a support. This juice is like glue and fastens the tendril very tightly.

Other plants—the trumpet vine, the poison ivy, and the English ivy—have aerial roots which attach themselves to the support. They like best to climb a brick or stone wall and these roots occupy the chinks or dark places of the wall or of the bark if they are climbing upon the trunk of a tree.

Some plants just scramble up. The tall blackberry has hooks and prickles all over its stems and leaves which hold fast to any support they may happen to find.

Climbers can get very high into the air with¬ out wasting effort in building strong stout trunks as trees do. They can get a great many leaves to the light and can grow very swiftly. Many of them have very long stems, from fifty to three hundred feet long. In the hot damp countries there are vines with stems as long as one thousand feet, which is nearly a fifth of a

Climbers have

different

methods mile. Vines have one disadvantage. If they do not find a support, they cannot get their leaves into the light and as a result, they do not thrive so well. Climbing plants sometimes put on so many leaves that they shade the tree or bush they are leaning upon and injure it, and some¬ times even kill it by keeping the sunshine away.

Plants are like people in a great many re¬ spects, but in one way they are much more independent, for they can make their own food. Each plant, big and small, is a busy food factory, and the busiest workshop in the factory is the leaf. Whenever you see green leaves on a tree you may know that they are working hard at manufacturing food that will keep the tree alive and make it grow tall and strong. Let us take, for example, an oak leaf and see what happens in its workshop.

The first thing the leaf needs is water, and the veins which you have often noticed bring that. The water gets into the trees through the roots. It travels up the tree trunk through long narrow tubes which are connected to the veins.

Morning glories must have a support

How do plants get their food?

The arrangement is something like the water pipes in a house. The water comes in at the basement, is brought upstairs through large pipes, and is passed on to many small pipes so that we may draw the water out of the faucets in several different rooms.

The next thing the leaf needs is carbon dioxide. Carbon dioxide is very familiar to you, although you may not know it by name. When you breathe you must have oxygen, but the air you breathe out is carbon dioxide. It is not good for human beings, and if there is too much in the room it makes us sick. That is why we need to have our windows opened and why we say, “We must have some fresh air.” A plant, however, is just the opposite from people for it breathes in carbon dioxide and breathes out oxygen. A leaf breathes through little holes on the under side of its surface. You cannot see them without a microscope.

A green leaf has the ability to take this water and carbon dioxide and put them together. The result is sugar, because sugar is made of carbon, oxygen, and hydrogen. Carbon dioxide is made of carbon and oxygen, and water is made of oxygen and hydrogen. You can see that there will be some oxygen left over; so the leaf breathes this out. This sugar is what the plant needs for food. It is sent all over the plant through slender tubes. We get our sugar from plants that make more than they can use—the sugar cane and sugar beets, for example.

The leaf can only make food when the sun is shining and the weather is warm. That is one reason why leaves drop off in autumn. They cannot work in winter, so the tree rests. The leaves do not work at night, either, because there is no sun. The tree must have food all winter, even if it isn’t working, and it must have some stored up to use in the spring until its leaf factory has a good start. Therefore the tree stores away some food, just as the squirrels store away nuts. It wouldn’t be a good idea to store the sugar because it dissolves in water and would soon be lost. Most plants have the power to change sugar into starch. The starch does

5 ° not dissolve in water so it will keep a long time. We often eat the starch that a plant has stored away. We do this when we eat potatoes, corn, and many other foods. Different plants store their winter food in different places. The trees store theirs in the roots and trunk. Potatoes are special storage rooms attached to the roots of the potato plant. Corn and wheat store their starch in the seeds because they are plants that live only one year, and the seed needs, some food to start on in the spring.

The leaf factory can only work in the sun¬ shine. That is why house plants should be near a window and why grass will not grow under a big tree which cuts off the light. Because light is needed this process of food making is called photosynthesis (pronounced fo'to-sin'- the-sis). Photo means light. It is the same Greek word that is found in photograph. Synthesis means “putting together.” The whole word means “putting together by means of light.” That is just what the leaf does. It puts water and carbon dioxide together when the sun is shining.

Leaves are factories word¬ ing in the sun

5 1

Only an expert can tell the age of living trees unless they are pines or spruces. Anyone can count the circles of branches on these trees. If there are ten rows, the tree will be ten years old. But anyone with sharp eyes can tell the age of a tree that has been cut down by counting the rings in the end of the log. Each ring stands for a year’s growth. The part nearest the center of the log is the oldest, and that nearest the bark is the newest. The grow¬ ing part of the tree is just under the bark. It is called the cambium (pronounced kam'- bi-um). The working parts of the tree trunk are near here also. Next to the cambium, on the inside, are the tissues that carry water up the tree. On the outside of the cambium, nearest to the bark, are the tissues that carry the food from the leaves to any part of the tree that needs it. All during the growing season, the cam¬ bium works very hard, forming new water¬ carrying and food-carrying tissues. Mixed with the water carriers are wood fibers also. Some¬ times the trunk becomes so much larger that it

The age of a tree can om the stump

How can we tell the age of trees?

is too big for the bark. The bark stretches and stretches and finally cracks. That is why bark is so rough and has such deep furrows.

As the summer comes to an end, the cam¬ bium, or growing part, grows more and more slowly, and when cold weather comes it stops altogether. This slowing up is easily seen at the outer edge of the ring as the wood has a different appearance. It is that which shows clearly the end of one year’s growth and the beginning of the next. The ring of wood formed during a favorable season—that is, a spring and summer with plenty of rain and sunshine—is wide. If the season was too dry, the ring is narrow. Just as each summer is different from the last one, so each ring differs from every other. Men who have had a great deal of experience in examining annual rings can tell what kind of weather there was during a certain year by looking at the rings. This is very useful when studying extremely old trees such as the big trees of California. These trees are so very old that they were growing before any of our American history was written, or indeed, even thought of. But experts can tell something about the weather five hundred or a thousand years ago by examining the logs. A ring that is very thin means a dry season. A wide one means a rainy year. Several narrow ones close together mean there was a period of dry weather lasting for some years. Many of these huge trees have over a thousand rings, showing that they are over a thousand years old. Most of the logs cut down for lumber from the pine and oak forests have from thirty to one hundred rings. Some of these trees, however, are even younger.