Outlines of Lessons in Botany, Part I; From Seed to Leaf - Jane H. Newell
OUTLINES OF LESSONS IN BOTANY.
PART I.: FROM SEED TO LEAF
FOR THE USE OF TEACHERS, OR MOTHERS STUDYING WITH THEIR CHILDREN.
BY
JANE H. NEWELL.
ILLUSTRATED BY H.P. SYMMES
1888.
PART I
TABLE OF CONTENTS
I. PLANTS AND THEIR USES
1. Food
2. Clothing
3. Purification of the Air
4. Fuel
II. SEEDLINGS
1. Directions for raising in the Schoolroom
2. Study of Morning-Glory, Sunflower, Bean, and Pea
3. Comparison with other Dicotyledons
4. Nature of the Caulicle
5. Leaves of Seedlings
6. Monocotyledons
7. Food of Seedlings
III. ROOTS
1. Study of the Roots of Seedlings
2. Fleshy Roots
3. Differences between Stem and Root
4. Root-hairs
5. Comparison of a Carrot, an Onion, and a Potato
IV BUDS AND BRANCHES
1. Horsechestnut
Magnolia
Lilac
Beech
American Elm
Balm of Gilead
Tulip-tree
Cherry
Red Maple
Norway Spruce
2. Vernation
3. Phyllotaxy
V STEMS
1. Forms
2. Movements
3. Structure
VI LEAVES
1. Forms and Structure
2. Descriptions
3. Transpiration
4. Assimilation
5. Respiration
PREFACE.
In this study, as in all scientific teaching, the teacher's aim should
be to foster in his pupils the power of careful observation and clear
expression. The actual amount of knowledge gained at school must needs be
small, and often quickly forgotten, but the habit of right study is an
invaluable possession.
The former method of teaching Botany was confined almost wholly to dry,
technical classification. The pupil learned to find the name and order of
a plant, but its structure, its habits, its life in short, were untouched
by him. We know now that Nature is the best text-book. The pupil should
first ask his questions of her and try to interpret her answers; then he
may learn with profit what those who better understand her speech have to
tell him.
This method of teaching, however, requires much, very much, of the
teacher. He must be himself intelligent, well trained, and able to give
time to the preparation of his lessons. It seems to us, who are but
amateurs, as if it were impossible to teach thus without a thorough
comprehension of the whole field. Our own ignorance oppresses us so much
that we feel tempted to say that we cannot attempt it. But if the work of
leading children to observe the wonders about them is to be done at all,
it must be done by us, who are not masters of our subject, and we must
find out for ourselves how we can best accomplish this result, since we
have so little to guide us.
It is with the hope that the experience of one who has tried to do
this with some fair amount of success may be of use to other puzzled
experimenters, that I venture to write out some outlines of lessons in
Botany for beginners.
The method of beginning with the simpler forms of life is one that appeals
to the scientific tendencies of the day. It seems logical to begin with
lower forms and work up to the higher. But this method is only suitable
for mature minds. We do not teach a child English by showing him the
sources of the language; he learns it by daily use. So also the beginning
of the study of any Natural Science by the young should be the observation
of the most obvious things about them, the things which they can see, and
handle, and experiment upon naturally, without artificial aids. Therefore
this book concerns itself only with the Flowering Plants.
The author believes that the simplest botanical study should afford the
means of identifying plants, as a large part of the student's pleasure in
the science will be the recognition of the things about him. The present
volume affords the basis for future classification, which Part II, on
flowers, will develop. It is, doubtless, as good a way, perhaps the best,
to begin with a single plant, and study root, stem, leaves, and flowers
as belonging to a whole, but the problem is complicated by practical
difficulties. In our climate there are but two months of the school year
when flowers are easily obtained. On the other hand, the material for
these lessons can be got throughout the winter, and the class, well
trained in methodical work, will begin the study of flowers at the season
when every day brings some fresh wonder of beauty.
The author will receive gladly any criticisms or suggestions.
JANE H. NEWELL.
175 Brattle St., Cambridge
INTRODUCTION.
The lessons here outlined are suitable for children of twelve years of
age, and upwards. For younger pupils they would require much adaptation,
and even then they would not be so good as some simpler method, such as
following the growth of one plant, and comparing it with others at every
step. The little ones profit most by describing the very simple things
that they see, without much reference to theories.
The outlines follow the plan of Dr. Gray's First Lessons and How Plants
Grow, and are intended to be used in connection with either of those
books. The necessary references will be found at the end of every section.
The book contains also references to a course of interesting reading in
connection with the subjects of the lessons.
The lessons may begin, like the text-books, with the subject of
Germination, if the seeds are planted before they are required for use,
but it is generally preferable to use the first recitation with the class
for planting the seeds, in order to have them under the direct care of the
pupils. Some general talks about plants are therefore put at the beginning
to occupy the time until the seedlings are ready for study.
Some Nasturtiums (_Tropaeolum majus_) and Morning-Glories should be planted
from the first in boxes of earth and allowed to grow over the window, as
they are often used for illustrations.
I.
PLANTS AND THEIR USES.[1]
[Footnote 1: This section may be omitted, and the lessons begun with
Seedlings, if the teacher prefer.]
What is Botany? The pupils are very apt to say at first that it is
learning about _flowers_. The teacher can draw their attention to the fact
that flowers are only a part of the plant, and that Botany is also the
study of the leaves, the stem, and the root. Botany is the science of
_plants_. Ask them what the Geranium is. Tell them to name some other
plants. The teacher should keep a few growing plants in the schoolroom for
purposes of illustration.
Ask them what else there is in the world besides plants. By this question
the three kingdoms, animal, vegetable, and mineral, are brought up. It
will give occasion for a discussion of the earth and what it contains, the
mountains, formed of rocks and soil, the plants growing on the earth,
and the animals that inhabit it, including man. Let them name the three
kingdoms with some example of each. Which of these kingdoms contain living
things? The words _organic_ and _inorganic_ can be brought in here. An
_organ_ ([Greek: Ergon], meaning work) is any part that does a special
work, as the leaves, the stem of a plant, and the eye, the ear of animals.
An _organism_ is a living being made up of such organs. The inorganic
world contains the mineral kingdom; the organic world includes the
vegetable and animal kingdoms.
One's aim in these lessons should always be to tell the pupils as little
as possible. Try to lead them to think out these things for themselves.
Ask them how plants differ from animals. They will say that plants are
fixed to one place, while animals can move about; that plants have no will
or consciousness, and that animals have. These answers are true when we
compare the higher animals with plants, but the differences become lost as
we descend in the scale and approach the border land where botanist and
zoologist meet on a common ground. Sea-anemones are fixed to the rock on
which they grow, while some of the lower plants are able to move from
place to place, and it is hardly safe to affirm that a jelly-fish is more
conscious of its actions than is a Sensitive Plant, the leaves of which
close when the stem is touched.
There is no real division between animals and plants. We try to classify
the objects about us into groups, according to the closeness of their
relationships, but we must always remember that these hard lines are ours,
not Nature's. We attempt, for purposes of our own convenience, to divide a
whole, which is so bound together that it cannot be separated into parts
that we can confidently place on different sides of a dividing line.
1. _Plants as Food-Producers_.--The chief distinguishing characteristic of
plants is one that the pupils may be led to think out for themselves by
asking them what animals feed upon. To help them with this, ask them what
they had for breakfast. Oatmeal is mentioned, perhaps. This is made from
oats, which is a plant. Coffee and tea, bread made from wheat, potatoes,
etc., all come from plants.[1] Beef, butter and milk come from the cow,
but the cow lives upon grass. The plant, on the other hand, is nourished
upon mineral or inorganic matter. It can make its own food from the soil
and the air, while animals can only live upon that which is made for
them by plants. These are thus the link between the mineral and animal
kingdoms. Ask the scholars if they can think of anything to eat or drink
that does not come from a plant. With a little help they will think of
salt and water. These could not support life. So we see that animals
receive all their food through the vegetable kingdom. One great use of
plants is that they are _food-producers_.
[Footnote 1: Reader in Botany, for use in Schools. Selected and adapted
from well-known authors. Ginn & Co., Boston, New York and Chicago, 1889.
I. Origin of Cultivated Plants.]
This lesson may be followed by a talk on food and the various plants used
for food.[2]
[Footnote 2: The Flour Mills of Minneapolis: Century Magazine, May, 1886.
Maize: Popular Science News, Nov. and Dec., 1888.]
2. _Clothing_.--Plants are used for clothing. Of the four great clothing
materials, cotton, linen, silk, and woollen, the first two are of
vegetable, the last two of animal origin. Cotton is made from the hairs of
the seed of the cotton plant.[1] Linen is made of the inner fibre of
the bark of the flax plant. It has been cultivated from the earliest
historical times.
[Footnote 1: Reader in Botany. II. The Cotton Plant.]
3. _Purification of the Air_.--The following questions and experiments are
intended to show the pupils, first, that we live in an atmosphere, the
presence of which is necessary to support life and combustion (1) and (2);
secondly, that this atmosphere is deprived of its power to support life
and combustion by the actions of combustion (2), and of respiration (3);
thirdly, that this power is restored to the air by the action of plants
(4).
We have the air about us everywhere. A so-called empty vessel is one
where the contents are invisible. The following experiment is a good
illustration of this.
(1) Wrap the throat of a glass funnel with moistened cloth or paper so
that it will fit tightly into the neck of a bottle, and fill the funnel
with water. If the space between the funnel and the bottle is air-tight,
the water will not flow into the bottle.
[Illustration: FIG. 1.]
Do not explain this in advance to the pupils. Ask them what prevents
the water from flowing into the bottle. If they are puzzled, loosen the
funnel, and show them that the water will now flow in. In the first case,
as the air could not escape, the water could not flow in; in the second,
the air was displaced by the heavier water.
Ask the pupils why the air in a crowded room becomes so difficult to
breathe. Could a person live if he were shut up in an air-tight room for a
long time? Fresh air is necessary to life. The teacher may explain that it
is the oxygen in the air that supports life. Air is composed one-fifth of
this gas and four-fifths of nitrogen. The gases are mixed and the nitrogen
simply dilutes the oxygen, as it were.
Fresh air is necessary to support combustion as well as life. Ask them why
we put out a fire by throwing a blanket or a rug over it. The following
experiment illustrates this.
(2) Take a small, wide-mouthed bottle, covered with a card or cork. To
this cover fasten a piece of bent wire with a taper on the end. Light the
taper and lower it into the jar. It will burn a few seconds and then go
out. Raise and light it again, and it will be extinguished as soon as it
is plunged into the bottle. This shows that the oxygen of the air is used
up by burning substances, as it is by breathing animals.
[Illustration: FIG. 2.]
The following experiment shows that fire will not burn in an atmosphere of
gas from our lungs.
(3) Fill a bottle with gas by breathing into it through a bit of glass
tubing, passed through a card or cork, and reaching to the bottom of the
bottle. The bottle will be dimmed with moisture, showing the presence of
aqueous vapor. A lighted match plunged into the bottle will be immediately
extinguished. A better way, which, however, takes some skill in
manipulation, is to fill the bottle with water, cover it with a flat piece
of glass, and invert the bottle in a dish of water, taking care that no
air bubbles enter. Then, through a bit of glass tubing, blow into the
bottle till the water is expelled. Cover the mouth with the glass under
water, and holding it tightly down, invert the bottle quickly. Set it
down, light a match, take away the glass, and at the same instant plunge
in the match. If no air has been allowed to enter, the match will go out
at once. No animal could live in an atmosphere which could not support
combustion.
From these experiments the pupils have seen that the life-sustaining
quality of the air is used up by combustion and respiration. To bring in
the subject of purification by plants, ask them why all the oxygen in
the world is not exhausted by the people and the fires in it. After the
subject has been explained, the following experiment can be prepared and
put aside till the next lesson.
(4) Fill two bottles with air from the lungs, as in (3) having previously
introduced a cutting from a plant into one of the bottles. Allow them to
stand in the sun for a day or two. Then test both bottles with a burning
match. If properly done, the result will be very striking. The end of
the cutting should be in the water of the dish. This experiment will not
succeed excepting with bottles such as are used for chemicals, which have
their mouths carefully ground. Common bottles allow the air to enter
between the bottle and the glass.[1]
[Footnote 1: See note on page 13.]
[Illustration: FIG. 3.]
4. _Fuel_.--Light a match and allow it to burn until half charred. Blow it
out gently, so as to leave a glowing spark. When this spark goes out it
will leave behind a light, gray ash. We have to consider the flame, the
charred substance, and the ash.
Flame is burning gas. In all ordinary fuels, carbon and hydrogen, in
various combinations and free, make the principal part. The first effect
of the heat is to set free the volatile compounds of carbon and hydrogen.
The hydrogen then begins to unite with the oxygen of the air, forming
water, setting free the carbon, which also unites with oxygen, forming
carbonic acid gas. The burning gases cause the flame. The following
experiment will illustrate this.
[Illustration: Fig. 4.]
(5) Fit a test-tube with a tight cork, through which a bit of glass
tubing, drawn out into a jet, is passed, the tubing within being even with
the cork. Place some bits of shaving in the tube, cork it, and make the
cork perfectly air-tight by coating it with bees wax or paraffine. Heat
the test-tube gently over an alcohol lamp. The wood turns black, and vapor
issues from the jet, which may be lighted (Fig. 4). Care should be taken
to expel all the air before lighting.
(6) That the burning hydrogen forms water by uniting with the oxygen of
the air, may be shown by holding a cold glass tumbler over the jet, or
over any flame. The glass will be dimmed by drops of moisture.
The charred part of the wood is charcoal, which is one form of carbon.
Our ordinary charcoal is made by driving off all the gases from wood, by
burning it under cover where only a little air can reach it. The volatile
gases burn more readily than the carbon, and are the first substances to
be driven off, so that the carbon is left behind nearly pure. In the same
way we have driven off all the gases from the half-burned match and left
the carbon. The teacher should have a piece of charcoal to show the
pupils. It still retains all the markings of the wood.
If the combustion is continued, the carbon also unites with the oxygen of
the air, till it is all converted into carbonic acid gas. This was the
case with the match where we left the glowing spark. The gray ash that was
left behind is the mineral matter contained in the wood.
(7) We can show that this gas is formed by pouring lime water into a
bottle in which a candle has been burned as in (2). The water becomes
milky from a fine white powder formed by the union of the carbonic acid
gas with the lime, forming carbonate of lime. This is a chemical test.
The wood of the match is plainly of vegetable origin; so also is the
charcoal, which is nearly pure carbon. Coal is also carbon, the remains of
ancient forests, from which the gases have been slowly driven off by heat
and pressure. All the common fuels are composed principally of carbon and
hydrogen. When these elements unite with oxygen, carbonic acid gas and
water are formed.[1]
[Footnote 1: [Transcriber's Note: This note is missing from original
text.]]
(8) The same products are formed by respiration. We breathe out carbonic
acid gas and water from our lungs. Breathe on a cold glass. It is bedewed
exactly as it is by the candle flame. Breathe through a bit of glass
tubing into a bottle of lime water. It becomes milky, showing the presence
of carbonic acid gas. Why is this?
Every act or thought is accompanied by a consumption of material in the
body, which thus becomes unfit for further use. These waste substances,
composed chiefly of carbon and hydrogen, unite with oxygen breathed in
from the air, forming carbonic acid gas and water, which are breathed
out of the system. The action is a process of slow combustion, and it is
principally by the heat thus evolved that the body is kept warm. As we are
thus constantly taking oxygen from the air, a close room becomes unfit to
live in and a supply of fresh air is indispensable. The cycle of changes
is completed by the action of plants, which take in carbonic acid gas, use
the carbon, and return most of the oxygen to the atmosphere.
APPARATUS FOR EXPERIMENTS.[1]
[Footnote 1: The glass apparatus required, including an alcohol lamp, may
be obtained for one dollar by sending to the Educational Supply Co., No. 6
Hamilton Place, Boston.]
Two small wide-mouthed bottles. A narrow-necked bottle. A glass funnel. A
bit of bent glass-tubing. A bit of straight glass-tubing. A flat piece of
glass. A test-tube, with jet. An alcohol lamp. A bent wire with taper.
A card. A slip of a plant. A dish and pitcher of water. Beeswax or
paraffine. Shavings. Lime water. Matches.
_Gray's First Lessons. Revised edition_. Sect. XVI, 445-7, 437.
_How Plants Grow_. Chap. III, 279-288.
II.
SEEDLINGS.
1. _Directions for raising in the Schoolroom_.--The seeds should be
planted in boxes tilled with clean sand. Plates or shallow crockery pans
are also used, but the sand is apt to become caked, and the pupils are
likely to keep the seeds too wet if they are planted in vessels that
will not drain. The boxes should be covered with panes of glass till the
seedlings are well started, and should be kept at a temperature of from
65 deg. to 70 deg. Fahr. It is very important to keep them covered while
the seeds are germinating, otherwise the sand will be certain to become
too dry if kept in a sufficiently warm place. Light is not necessary, and
in winter time the neighborhood of the furnace is often a very convenient
place to keep them safe from frost. They should not be in the sun while
germinating. When the first sprouts appear above the ground let another
set be planted, and so on, till a series is obtained ranging from plants
several inches high to those just starting from the seed. The seeds
themselves should be soaked for a day and the series is then ready
for study. The time required for their growth varies according to the
temperature, moisture, etc. Dr. Goodale says they should be ready in ten
days.[1]
[Footnote 1: Concerning a few Common Plants, by G.L. Goodale, Boston, D.C.
Heath & Co. This little book, which is published, in pamphlet form, for
fifteen cents, will be found exceedingly useful.]
I have never been able to raise them so quickly in the schoolroom, nor
have the pupils to whom I have given them to plant done so at home.
Generally, it is three weeks, at least, before the first specimens are as
large as is desirable.
Germinating seeds need warmth, moisture and air. The necessary conditions
are supplied in the very best way by growing them on sponge, but it would
be difficult to raise enough for a large class in this manner. Place a
piece of moist sponge in a jelly-glass, or any glass that is larger at the
top, so that the sponge may not sink to the bottom, and pour some water
into the glass, but not so much as to touch the sponge. The whole should
be covered with a larger inverted glass, which must not be so close as
to prevent a circulation of air. The plants can thus be watched at every
stage and some should always be grown in this way. The water in the
tumbler will keep the sponge damp, and the roots, after emerging from
the sponge, will grow well in the moist air. Seeds can also be grown on
blotting paper. Put the seeds on several thicknesses of moist blotting
paper on a plate, cover them with more moist paper, and invert another
plate over them, taking care to allow the free entrance of air.
If possible, it is by far the best way to have the seeds growing in the
schoolroom, and make it a regular custom for the pupils to observe them
every morning and take notes of their growth.
These lessons on seeds are suitable for pupils of every age, from adults
to the youngest children who go to school. The difference should be only
in the mode of treatment; but the same principles should be brought out,
whatever the age and power of comprehension of the pupil.
For these lessons the following seeds should be planted, according to the
above directions:
Morning-Glory, Sunflower or Squash, Bean, Pea, Red Clover, Flax, Corn,
Wheat, and Oats.[1] If they can be procured plant also acorns, Pine-seeds,
Maple-seeds, and horsechestnuts.
[Footnote 1: A package of these seeds may be obtained for fifty cents,
from Joseph Breck & Son, Boston, Mass. They will be sent by mail, postage
paid.]
2. _Study of Morning-Glory, Sunflower, Bean, and Pea_.--For reasons
hereafter given, I consider the Morning-Glory the best seedling to begin
upon. Having a series, as above described, before them, the pupils should
draw the seedlings. When the drawings are made, let them letter alike the
corresponding parts, beginning with the plantlet in the seed, and using
new letters when a new part is developed. The seed coats need not be
lettered, as they do not belong to the plantlet.
[Illustration: FIG. 5.--Germination of Morning Glory, _a_, caulicle; _b_,
cotyledons; _c_, plumule; _d_, roots.]
[Illustration: FIG. 6.--Germination of Sunflower.]
After drawing the Morning-Glory series, let them draw the Sunflower or
Squash in the same way, then the Bean, and finally the Pea. Let them write
answers to the following questions:
MORNING-GLORY.[1]
[Footnote 1: It has been objected that the Morning-Glory seed is too small
to begin upon. If the teacher prefer, he may begin with the Squash, Bean,
and Pea. The questions will require but little alteration, and he can take
up the Morning-Glory later.]
Tell the parts of the Morning-Glory seed.
What part grows first?
What becomes of the seed-covering?
What appears between the first pair of leaves?
Was this to be seen in the seed?
How many leaves are there at each joint of stem after the first pair?
How do they differ from the first pair?
SUNFLOWER OR SQUASH.
What are the parts of the seed?
What is there in the Morning-Glory seed that this has not?
How do the first leaves change as the seedling grows?
BEAN.
What are the parts of the seed?
How does this differ from the Morning-Glory seed?
How from the Sunflower seed?
How do the first pair of leaves of the Bean change as they grow?
How many leaves are there at each joint of stem?[1]
[Footnote 1: There are two simple leaves at the next node to the
cotyledons; after these there is one compound leaf at each node.]
How do they differ from the first pair?
PEA.
What are the parts of the seed? Compare it with the Morning-Glory,
Sunflower, and Bean.
How does it differ in its growth from the Bean?
What have all these four seeds in common?