_is_. The deep “how” and “why” of things I cannot explain. Even the
very wisest men do not know all the how and the why of the “leaf-green”
fairy.
I have told you these few things that you may have wonders to think of
when you see green leaves. After this lesson, will you not care more
for seeds and leaves than you ever did before?
LESSON VIII.
THE COLOR OF PLANTS.
Almost the first thing that you will notice about a plant is its color.
The little child, before it can speak, will hold out its hands for a
bright red rose, or a golden lily. I think the color is one of the most
wonderful things about a plant.
Come into the field. Here you see a yellow buttercup, growing near a
white daisy. Beside them is a red rose. Close by, blooms a great purple
flower. All grow out of the same earth, and breathe the same air. Yet
how they differ in color.
Some flowers have two or three colors upon each petal. Have you not
seen the tulip with its striped blossoms, and the petunias spotted with
white and red?
The flower of the cotton plant changes in color. Within a few days this
flower appears in three distinct hues. The chicory blossom changes from
blue to nearly white as the day grows warm.
Look at your mother’s roses. Some are white, others are red, pink, or
yellow. None are ever blue.
Then look at a wild-rose tree. The root and stem are brown. The green
color is in the leaves, and in some of the stems. The petals are red.
The stamens and pistils are yellow.
You never saw the red color get astray and run into the leaves. The
leaf-green did not lose itself, and travel up to the petals. The
stamens and pistils did not turn brown instead of golden.
Does not that seem a wonder, now that you think of it? Perhaps you
never noticed it before. It is one thing to see things, and another to
notice them so that you think about them.
Here is another fact about color in plants. All summer you see that the
leaves are green. In the autumn they begin to change. You wake up some
fine frosty morning and the tree leaves are all turned red, yellow,
brown, or purple. It is a fine sight.
It is the going away of the leaf-green from the leaf that begins the
change of leaf-color in the fall. The leaves have done growing. Their
stems are hard and woody. They do not breathe as freely as they did.
The sap does not run through them as it did early in the season.
The leaf-green shrinks up in the cells. Or, it goes off to some other
part of the plant. Sometimes part of it is destroyed. Then the leaves
begin to change.
Sometimes a red sap runs into the leaf cells. Or, an oily matter goes
there, in place of the “leaf-green.”
The leaf-green changes color if it gets too much oxygen. In the autumn
the plant does not throw out so much oxygen. What it keeps turns the
leaf-green from green to red, yellow, or brown.
The bright color in plants is not in the flower alone. You have seen
that roots and seeds have quite as bright colors as blossoms. What
flowers are brighter than many fruits are?
The cherry is crimson, or pink, or nearly black. What a fine yellow,
red, purple, we find in plums! Is there any yellow brighter than that
of the Indian corn? Is there a red gayer than you find on the apples
you like so well? What is more golden than a heap of oranges?
If you wish to find splendid color in a part of a plant, look at a
water-melon. The skin is green marked with pale green, or white. Next,
inside, is a rind of pale greenish white. Then comes a soft, juicy,
crimson mass. In that are jet black seeds.
Oh, where does all this color come from? Why is it always just in the
right place? The melon rind does not take the black tint that belongs
to the seeds. The skin does not put on the crimson of the pulp. See,
too, how this color comes slowly, as the melon ripens. At first the
skin is of the same dark green as the leaves, and inside all is of a
greenish white.
Let us try to find out where all this color comes from. Do you know we
ourselves can make changes in the color of flowers? Take one of those
big hydrangeas. It has a pink flower. But give it very rich black earth
to grow in. Mix some alum and iron with the earth. Water it with strong
bluing water. Lay soot and coal-dust upon the earth it grows in. Very
soon your hydrangea will have blue flowers, instead of pink ones.
Once I had a petunia with large flowers of a dirty white color. I fed
it with soot and coal-dust. I watered it with strong bluing water.
After a few weeks my petunia had red or crimson flowers. Some of the
flowers were of a very deep red. Others were spotted with red and white.
Now from this you may guess that the plant obtains much of its color
from what it feeds on in the soil.
But you may give the plant very good soil, and yet if you make it grow
in the dark, it will have almost no color. If it lives at all, even the
green leaves will be pale and sickly.
This will show you that the light must act in some way on what the
plant eats, to make the fine color.
The plant, you know, eats minerals from the earth. In its food it gets
little grains of coloring stuff.
But how the color goes to the right place we cannot tell. We cannot
tell why it is, that from the same earth, in the same light, there
will be flowers of many colors. We cannot tell why flowers on the same
plant, or parts of the same flower, will have different colors. That is
one of the secrets and wonders that no one has found out.
There are many plants which store up coloring matter, just as plants
store up starch, or sugar. The indigo, which makes our best blue dye,
comes from a plant. Ask your mother to show you some indigo. When the
plant is soaked in water the coloring stuff sinks to the bottom of the
water, like a blue dust.
Did you ever notice the fine red sumac? That gives a deep yellow dye.
The saffron plant is full of a bright orange color. Other plants give
other dyes.
Sometimes children take the bright petals of plants, or stems, that
have bright color in them, to paint with. Did you ever do that? You can
first draw a picture, and then color it, by rubbing on it the colored
parts of plants.
Some trees and plants, from which dyes are made, have the coloring
stuff in the bark or wood. That is the way with the logwood tree. The
best black dye is made from that.
You have seen how much dark red juice you can find in berries. Did you
ever squeeze out the red juice of poke or elder berries? It is like
red ink. Did you ever notice how strawberries stain your fingers red?
Grapes and blackberries make your lips and tongue purple.
No doubt you have often had your hands stained brown, for days, from
the husks of walnuts. All these facts will show you what a deal of
color is taken up from the soil by plants, changed by the sun, and
stored up in their different parts.
But the chief of all color in the plant is the leaf-green. We cannot
make a dye out of that.
Leaf-green is the color of which there is the most. It is the color
which suits the eye best of all. How tired we should be of crimson or
orange grass!
Though leaves and stems are generally green, there are some plants
which have stems of a bright red or yellow color. Yellow is the common
color for stamens and pistils. In some plants, as the tulip, the peach,
and others, the stamens are of a deep red-brown, or crimson, or pink,
or even black color.
LESSON IX.
THE MOTION OF PLANTS.
If I ask you what motion plants have, I think you will tell me that
they have a motion upward. You will say that they “grow up.” You will
not say that they move in the wind. You know that that is not the kind
of motion which I mean.
Some plants grow more by day, some by night. On the whole, there is
more growing done by day than by night. At night it is darker, cooler,
and there is more moisture in the air. The day has more heat, light,
and dryness. For these causes growth varies by day and by night.
Warmth and moisture are the two great aids to the growth of plants.
Heat, light, and wet have most to do with the motion of plants. For the
motion of plants comes chiefly from growth.
The parts of the plant the motion of which we shall notice, are, the
stems, leaves, tendrils, and petals. Perhaps you have seen the motion
of a plant stem toward the sunshine.
Did you ever notice in house plants, that the leaves and branches turn
to the place from which light comes to them? Did you ever hear your
mother say that she must turn the window plants around, so that they
would not grow “one-sided”?
Did you ever take a pot plant that had grown all toward one side, and
turn it around, and then notice it? In two or three weeks you would
find the leaves, stems, branches, bent quite the other way. First they
lifted up straight. Then they slowly bent around to the light.
Perhaps you have noticed that many flower stems stoop to the east in
the morning. Then they move slowly around. At evening you find them
bending toward the west.
This is one motion of stems. Another motion is that of long, weak
stems, such as those of the grape-vine or morning-glory. They will
climb about a tree or stick.
Such vines do much of their climbing by curling around the thing which
supports them. If you go into the garden, and look at a bean-vine, you
will see what fine twists and curves it makes about the beanpole.
Such twists or curves can be seen yet more plainly in a tendril. A
tendril is a little string-like part of the plant, which serves it for
hands.
Sometimes tendrils grow out of the tips of the leaves.
Sometimes they grow from the stem. Sometimes they grow from the end of
a leaf-stem in place of a final leaf.
Tendrils, as I told you before, are twigs, leaves, buds, or other parts
of a plant, changed into little, long clasping hands.
Now and then the long slender stem of a leaf acts as a tendril. It
twists once around the support which holds up the vine. Thus it ties
the stem of the vine to the support.
You have seen not only climbing plants, such as the grape-vine. You
have seen also creeping plants, as the strawberry and ground-ivy. You
will tell me that a climbing plant is one which travels _up_ something.
You will say, also, that a creeping plant is a vine which runs along
the ground.
The climbing plant helps itself along by tendrils. The creeping plant
has little new roots to hold it firm.
Look at the strawberry beds. Do you see some long sprays which seem to
tie plant to plant? Your father will tell you that they are “runners.”
The plant throws out one of these runners. Then at the end of the
runner a little root starts out, and fastens it to the ground. A runner
is very like a tendril. There are never any leaves upon it. But the
end of a tendril never puts out a bud. The end of the runner, where it
roots, puts out a bud.
This bud grows into a new plant. The new plant sends out its runners.
These root again, and so on. Thus, you see, a few strawberry plants
will soon cover a large space of ground.
There is a very pretty little fern, called the “walking fern,” which
has an odd way of creeping about. When the slender fronds[8] reach
their full length, some of the tallest ones bend over to the earth.
The tip of the frond touches the ground. From that tip come little
root-like fibres, and fix themselves in the earth. A new plant springs
up from them.
When the new plant is grown, a frond of that bends over and takes root
again. So it goes on. Soon there is a large, soft, thick mat of walking
fern upon the ground.
This putting out new roots to go on by is also the fashion of some
climbing plants. Did you ever notice how the ivy will root all along a
wall? Little strong roots put out at the joints of the stem, and hold
the plant fast.
All this motion in plants is due to growth. In very hot lands where
there is not only much heat, but where long, wet seasons fill the
earth with water, the growth of plants is very rapid.
In these hot lands, there are more climbing plants than in cool lands.
Some trees, which, in cool lands where they grow slowly, never climb,
turn to climbers in hot lands.
Some plants will twine and climb in hot weather, and stand up straight
alone in cool weather. This shows that in hot weather they grow so
fast that they cannot hold themselves up. When it is cool, they grow
slowly, and make more strong fibre. But we must leave the stem motions
of plants and speak of the motion of other parts.
Let me tell you how to try the leaf motion of plants. Take a house
plant to try, as that is where wind will not move the leaf. Get a piece
of glass about four or five inches square. Smoke it very black.
Lay it under the leaf, so that the point of the leaf bent down will be
half an inch from the glass.
Then take a bristle from a brush and put it in the tip of the leaf.
Run the bristle in the leaf so that the end will come beyond the leaf,
and just touch the glass. Leave it a night and a day. Then you will
find the story of the leaf’s travels written on the glass. As the leaf
moves, the bristle will write little lines in the black on the glass.
Try it.
As you have proved the motion of the leaf with your smoked glass, let
us look at leaf motion. There is, first, that motion which unfolds or
unrolls the leaf from the bud. That is made because, by feeding, the
plant is growing larger, and the leaf needs more room.
The leaf often has, after it is grown, a motion of opening and
shutting. Other leaves have a motion of rising and falling. But of
these motions I will tell you in another lesson.
Flowers have, first, the motion by which the flower-bud unfolds to the
full, open blossom. That, as the leaf-bud motion, comes from growing.
Did you ever watch a rose-bud, or a lily-bud, unfold?
Then the flowers of many plants have a motion of opening and shutting
each day. I shall tell you of that, also, in another lesson.
Besides these motions in plants, there are others. Did you ever see how
a plant will turn, or bend, to grow away from a stone, or something,
that is in its way?
If you watch with care the root of one of your bean-seeds, you will see
that it grows in little curves, now this way, now that. It grows so,
even when it grows in water, or in air, where nothing touches it.
People who study these changes tell us that the whole plant, as it
grows, has a turning motion. In this motion all the plant, and all its
parts, move around as they grow.
The curious reasons for this motion of plants, you must learn when
you are older. I can now tell you only a little about it. I will tell
you that the plant moves, because the little cells in it grow in a
one-sided way.
Thus the air, light, heat, moisture, cause the cells on one side of
the plant to grow larger than the others. Then the plant stoops, or is
pulled over, that way. It is bent over by the weight. Then that side is
hidden, and the other side has more light, heat, and wet. And as the
cells grow, it stoops that way.
This is easy to understand in climbing plants. Their long, slim stems
are weak. They bend with their own weight. They bend to the side that
is slightly heavier. Their motion then serves to find them a support.
As they sweep around, they touch something which will hold them up.
Then they cling to it.
Now, there is another reason for a tendril taking hold of anything. The
skin of the tendril is very soft and fine. As it lies against a string,
or stick, or branch, the touch of this object on its fine skin makes
the tendril bend, or curl.
It keeps on bending or curling, until it gets quite around the object
which it touches. Then it still goes on bending, and so it gets around
a second time, and a third, and so on. Thus the tendril makes curl
after curl, as closely and evenly as you could wind a string on a stick.
Some plants, as the hop, move around with the sun; other plants move in
just the other direction. It is as if some turned their faces, and some
their backs, to the sun.
FOOTNOTES:
[8] What you call the leaf of a fern is, properly speaking, a frond.
LESSON X.
PLANTS AND THEIR PARTNERS.
Did I not tell you that the plants had taken partners and gone into
business? I said that their business was seed-growing, but that the
result of the business was to feed and clothe the world.
In our first lessons we showed you that we get all our food, clothes,
light, and fuel, first or last, from plants. “Stop! stop!” you say.
“Some of us burn coal. Coal is a mineral.” Yes, coal is a mineral now,
but it began by being a vegetable. All the coal-beds were once forests
of trees and ferns. Ask your teacher to tell you about that.
[Illustration: THE THREE PARTNERS.]
If all these things which we need come from plants, we may be very glad
that the plants have gone into business to make more plants.
Who are these partners which we told you plants have? They are the
birds and the insects. They might have a sign up, you see, “Plant,
Insect & Co., General Providers for Men.”
Do let us get at the truth of this matter at once! Do you remember
what you read about the stamens and pistils which stand in the middle
of the flower? You know the stamens carry little boxes full of pollen.
The bottom of the pistil is a little case, or box, full of seed germs.
You know also that the pollen must creep down through the pistils, and
touch the seed germs before they can grow to be seeds. And you also
know, that unless there are new seeds each year the world of plants
would soon come to an end.
Now you see from all this that the stamens and pistils are the chief
parts of the flower. The flower can give up its calyx, or cup, and its
gay petals, its color, honey, and perfume. If it keeps its stamens and
pistils, it will still be a true seed-bearing flower.
It is now plain that the aim of the flower must be to get that
pollen-dust safely landed on the top of the pistil.
You look at a lily, and you say, “Oh! that is very easy. Just let those
pollen boxes fly open, and their dust is sure to hit the pistil, all
right.”
But not so fast! Let me tell you that many plants do not carry the
stamens and pistils all in one flower. The stamens, with the pollen
boxes, may be in one flower, and the pistil, with its sticky cushion to
catch pollen, may be in another flower.
More than that, these flowers, some with stamens, and some with
pistils, may not even be all on one plant! Have you ever seen a
poplar-tree? The poplar has its stamen-flowers on one tree, and its
pistil-flowers on another. The palm-tree is in the same case.
Now this affair of stamen and pistil and seed making does not seem
quite so easy, does it? And here is still another fact. Seeds are the
best and strongest, and most likely to produce good plants, if the
pollen comes to the pistil, from a flower not on the same plant.
This is true even of such plants as the lily, the tulip, and the
columbine, where stamens and pistils grow in one flower.
Now you see quite plainly that in some way the pollen should be carried
about. The flowers being rooted in one place cannot carry their pollen
where it should go. Who shall do it for them?
Here is where the insect comes in. Let us look at him. Insects vary
much in size. Think of the tiny ant and gnat. Then think of the great
bumble bee, or butterfly. You see this difference in size fits them to
visit little or big flowers.
You have seen the great bumble bee busy in a lily, or a trumpet flower.
Perhaps, too, you have seen a little ant, or gnat, come crawling out
of the tiny throat of the thyme or sage blossom. And you have seen the
wasp and bee, busy on the clover blossom or the honeysuckle.
Insects have wings to take them quickly wherever they choose to go.
Even the ant, which has cast off its wings,[9] can crawl fast on its
six nimble legs.
Then, too, many insects have a long pipe, or tongue, for eating. You
have seen such a tongue on the bee.[10] In this book you will soon read
about the butterfly, with its long tube which coils up like a watch
spring.
With this long tube the insect can poke into all the slim cups, and
horns, and folds, of the flowers of varied shapes.
Is it not easy to see that when the insect flies into a flower to feed,
it may be covered with the pollen from the stamens? Did you ever watch
a bee feeding in a wild rose? You could see his velvet coat all covered
with the golden flower dust.
Why does the insect go to the flower? He does not know that he is
needed to carry pollen about. He never thinks of seed making. He goes
into the flower to get food. He eats pollen sometimes, but mostly
honey.
In business, you know, all the partners wish to make some profit for
themselves. The insect partner of the flower has honey for his gains.
The flower lays up a drop of honey for him.
In most flowers there is a little honey. Did you ever suck the sweet
drop out of a clover, or a honeysuckle? This honey gathers in the
flower about the time that the pollen is ripe in the boxes. Just at the
time that the flower needs the visit of the insects, the honey is set
ready for them.
Into the flower goes the insect for honey. As it moves about, eating,
its legs, its body, even its wings, get dusty with pollen. When it has
eaten the honey of one flower, off it goes to another. And it carries
with it the pollen grains.
As it creeps into the next flower, the pollen rubs off the insect upon
the pistil. The pistil is usually right in the insect’s way to the
honey. The top of the pistil is sticky, and it holds the pollen grains
fast. So here and there goes the insect, taking the pollen from one
flower to another.
But stop a minute. The pollen from a rose will not make the seed
germs of a lily grow. The tulip can do nothing with pollen from a
honeysuckle. The pollen of a buttercup is not wanted by any flower but
a buttercup. So of all. The pollen to do the germ any good must come
from a flower of its own kind.
What is to be done in this case? How will the insect get the pollen to
the right flower? Will it not waste the clover pollen on a daisy?
Now here comes in a very strange habit of the insect. Insects fly
“from flower to flower,” but they go from flowers of one kind to other
flowers of the _same kind_. Watch a bee. It goes from clover to clover,
not from clover to daisy.
Notice a butterfly. It flits here and there. But you will see it settle
on a pink, and then on another pink, and on another, and so on. If it
begins with golden rod, it keeps on with golden rod.
God has fixed this habit in insects. They feed for a long time on the
same kind of flowers. They do this, even if they have to fly far to
seek them. If I have in my garden only one petunia, the butterfly which
feeds in that will fly off over the fence to some other garden to find
another petunia. He will not stop to get honey from my sweet peas.
Some plants have drops of honey all along up the stem to coax ants or
other creeping insects up into the flower.
But other plants have a sticky juice along the stem, to keep crawling
insects away. In certain plants the bases of the leaf-stems form little
cups, for holding water. In this water, creeping insects fall and drown.
Why is this? It is because insects that would not properly carry the
pollen to another flower, would waste it. So the plant has traps, or
sticky bars, to keep out the kind of insects that would waste the
pollen, or would eat up the honey without carrying off the pollen.
I have not had time to tell you of the many shapes of flowers. You must
notice that for yourselves.
Some are like cups, some like saucers, or plates, or bottles, or bags,
or vases. Some have long horns, some have slim tubes or throats. Some
are all curled close about the stamens and pistils.
These different kinds of flowers need different kinds of insects to get
their pollen. Some need bees with thick bodies. Some need butterflies
with long, slim tubes. Some need wasps with long, slender bodies and
legs. Some need little creeping ants, or tiny gnats.
Each kind of flower has what will coax the right kind of insects, and
keep away the wrong ones. What has the plant besides honey to coax the
insect for a visit? The flower has its lovely color, not for us, but
for insects. The sweet perfume is also for insects.
Flowers that need the visits of moths, or other insects that fly by
night, are white or pale yellow. These colors show best at night.
Flowers that need the visits of day-flying insects, are mostly red,
blue, orange, purple, scarlet.
There are some plants, as the grass, which have no sweet perfume and
no gay petals. I have told you of flowers which are only a small brown
scale with a bunch of stamens and pistils held upon it. And they have
no perfumes. These flowers want no insect partners. Their partner is
the summer wind! The wind blows the pollen of one plant to another.
That fashion suits these plants very well.
So, by means of insect or wind partners, the golden pollen is carried
far and wide, and seeds ripen.
But what about the bird partners? Where do they come in?