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John Swett




SCIENCE PRIMERS, edited by

PROFESSORS HUXLEY, RoSGOE, and
BALFOUR STEWART.



VIII
BOTANY.



BOTANY.



BY

J. D. HOOKER, C.B., P.R.S.



WITH ILLUSTRATIONS.



NEW YORK :
D. APPLETON AND COMPANY,

549 AND 551 BROADWAY.

i8 77 .



Q.K4









PREFACE.



THE object of this Primer is to supply an elementary
knowledge of the principal facts of plant-life, together
with the means of training beginners in the way to
observe plants methodically and accurately; and in
the way to apply the knowledge thus obtained to
the methodical study of Botany.

It is hoped that by its means the teacher may
convey a sound elementary knowledge of the number,
nature, relative positions and uses of the principal
organs of plants, of the order and way in which they
grow, and in which plants multiply, and of those
resemblances which exist amongst them, by a com-
parison of which their true relationships are known
and themselves classified.

In using this Primer the plants indicated are, when-
ever possible, to be put into each pupil's hand.
Hence, to facilitate its use, I have placed at the end
an Index of the plants referred to in it. These may
be procured in the country, or from any intelligent
nurseryman. Many of them should be grown in every
school-garden, and arranged in it systematically, so
that the teacher may have the same means of dis-
playing to his pupils the principles of classification
that the great founder of the natural classification of
plants, Bernard de Jussieu, had after he had thus



vi PREFACE.



arranged the Garden of the Palace of Trianon after
its establishment by Louis XV.

The teacher should further have a copious supply
of dried flowers, and other parts of these plants so
preserved as that the pupil can, after -moistening
them in warm water, separate their organs. Much
may thus be learnt when fresh plants cannot be
obtained, and a rehearsal of the summer's lessons
upon such dried specimens is a most improving
exercise. He should also have a supply of preserved
fruits, seeds, sections of stems, and of mounted pre-
parations of the tissues and minute parts of plants
adapted for exhibition under the microscope.

Each pupil should have a pocket-lens magnifying
three or four times, a sharp pen-knife, and a pair of
forceps ; and he should be taught to preserve between
sheets of paper the specimens he has examined, with
a descriptive ticket attached ; and also be exercised
in the habitual use of the schedules described at
pp. 112, 113.

In using the Primer the pupil should be taught
first, the contents of sections I. and II. ; after which
he may either take the other sections in order, or go
on to section VI., taking sections III. to V. after-
wards. Sections XIX. and XXV. are too difficult for
beginners.

After mastering its contents the pupil may proceed
to the use of Professor Oliver's " Lessons in Elemen-
tary Botany," which goes over the same ground in
more detail.



CONTENTS.



SECT. PAGE

I. INTRODUCTORY i

II. GENERAL CHARACTERS OF FLOWERING

PLANTS 8

III. THE TISSUES OF PLANTS ic

IV. THE GROWTH OF CELL-TISSUE, AND NATURE

OF THE CELL 13

V. THE FOOD OF PLANTS 20

VI. THE GROWING SEED 23

VII. THE ROOT 28

VIII. THE STEM 33

IX. THE BUDS AND BRANCHES 38

X. THE LEAVES 40

XI. THE INFLORESCENCE 45

XII. THE FLOWER 47

XIII. THE CALYX 62

XIV. THE COROLLA 63

XV. THE DISK 66

XVI. ^ESTIVATION 67

XVII. THE STAMEN 68

XVIII. THE PISTIL 72

XIX. THE OVULE 74

XX. FERTILIZATION 76

XXI. THE FRUIT 80

XXII. THE SEED 89

XXIII. SURFACE COVERINGS AND APPENDAGES . . 93

XXIV. GYMNOSPERMOUS PLANTS 95

XXV. CLASSIFICATION . 97

XXVI. PHYSIOLOGICAL EXPERIMENTS 102

XXVII. A SCHOOL-GARDEN OF FLOWERING PLANTS 107
XXVIII SCHEDULES FOR EXERCISES ON LEAVES

AND FLOWERS in

INDEX 114



LIST OF ILLUSTRATIONS.



PAGE

Fig. i. Cellular tissue of rounded cells 10

2. Cellular tissue of rather long cells .... 10

3. Thick-walled cells from a leaf of Stone-pine . 1 1

,, 4. Spiral-vessels with cellular tissue on each side . 12
5. Growing point of stem of Stonewort showing

formation of new cells by division .... 13

6. Starches 17

jj 7> 8, 9. Crystals of oxalate of lime, as found in

cells 19

10. Pea "24

ii. Germination of Mustard 25

12. Wheat germinating 26

13. Vertical section of tip of root-fibre of

Hyacinth 29

14. Root^hairs 30

15. Tubercles and root-fibres of Orchis .... 31

16. Creeping stems and roots of Couch-grass . . 32
17. Transverse section of vascular bundle from

stem of a Dicotyledon 35

,, 1 8. Transverse section of stem of a Dicotyledon . 35

19. Transverse section of stem of a Monocotyledon 37

20. Leaf-buds and vertical section of ditto ... 38

21. Fragment of epidermis with a stomate ... 43

22. Vertical section of Buttercup flower .... 51

23. Vertical section of Bramble flower .... 52

24. Vertical section of Wall-flower 52

25. Stamens of Wall-flower 52

26. Vertical section of flower of Mallow. ... 53

27. Section of flower of Pea 54

28. Vertical section of flower of China Primrose . 54

29. Transverse section of ovary 54

30. Vertical section of Dead-nettle flower ... 55

31. Vertical section of Rose 56

32. Vertical section of Apple flower 56

33. Vertical section of head of Daisy 57

34. Inner flower from head of Daisy 57

35. Vertical section of Daphne flower .... 58

36: Vertical section of Tulip flower 59

37. Vertical section of Daffodil flower .... 59

38. Male flower of Willow 60

39. Female flower of Willow 60

40. Spikelets of Wheat 6 1

41. Dandelion fruit with pappus 63



LIST OF ILLUSTRATIONS.



PAGE

Fig. 42. Thistle fruit with pappus 63

43. Spotted orchis- flower 64

44. Honey glands of Buttercup and Barberry . . 66
45. Disks of Orange and Mignonette .... 67

46. Estivations 68

47. Stamens of Pea 69

48. Stamens of Bilberry, Heath, Barberry, and

Mistletoe 70

49. Transition from stamen to petal, and to sepal,

in double rose 70

50. Pollen grains of Orange, and of Buttercup
upon the stigma with their tubes descending

to the ovule 71

51. Pollen grains of Evening Primrose, and Cherry,

both emitting pollen tubes 71

52. Axile ovules 73

53. Parietal ovules 73

54. Growth of ovule of Celandine 74

55. Longitudinal section of ovule of Heartsease . 75
56. Corolla of long-styled and short-styled Prim-
rose 77

57. Section of flower of Orchis, showing a bee
standing upon the lip with its head touching
the sticky gland to which the pollen masses
are attached ; bee's head with the pollen
masses as removed ; the same with the pollen
masses after they have moved forwards . . 79

58. Aggregate fruit of Mulberry 82

59. Fruit of Pig cut vertically; male and female

flowers 82

60. Section of fruit of Nettle ; section of seed of

the same, showing the embryo 83

61. Fruit of Pea splitting into two valves ... 84
62. Fruit of Buttercup, cut open showing the seed ;
seed of the same cut open showing the small
embryo within the small albumen .... 84
63. Fruit of Bramble with stamens and calyx be-
neath it 85

64. Fruit of Strawberry with calyx and bracts

beneath it 85

65. Fruit of Mallow surrounded with the calyx . 86

66. Fruit of Apple cut across 87

67. Pod of Wallflower with one valve coming off . 88
68. Experiment with bottle in basin 103



SCIENCE PRIMERS.



BOTANY.

I. INTRODUCTORY.

THE study of Botany is best commenced with the
careful observation of the different parts of living
plants, their positions and arrangement in reference
to one another, the order in which they make their
appearance, and their uses to the plant itself. It is
hence often called a science of observation, in con-
trast to Chemistry and other subjects of which the
study must necessarily commence with experiment.
But Botany is also an experimental science ; only the
experiments by which we investigate the growth of
plants, their modes of living and multiplying, and
their relations to the air and soil, require much to have
been learnt first by observation alone. Such experi-
ments require also for the most part a previous know-
ledge of Chemistry and Physics; those, however,
described in this Primer will need no more knowledge
of these subjects than is to be found in the Primers
devoted to them.

Plants are living things ; they form the Vege-
table Kingdom as animals form the Animal King-
dom. Like animals, plants pass through the stages



2 V J I 'SCIENCE PRIMERS. [i.

of in r ancy, ; ihatur;fy, arid death ; they also feed, grow,
and multiply. Unlike the higher animals, during the
ordinary processes of growth (with the exception of
germination and flowering) they have no proper heat,
not being warmer than the air or water in which they
live.

Duration of Plant-life. Some plants have
limited lives, flowering but once and dying soon after;
others have unlimited lives, throughout which they
flower periodically. Plants with limited lives are: i.
Annuals, which live but for one year or season, as
wheat, peas, &c. ; 2. Biennials which live for two
years, as the cabbage, turnip, foxglove, &c. ; and 3.
plants which grow for many years without flowering
(for example many palms), flower but once, and
then die. Those with unlimited lives are Perennials,
and may be either trees and shrubs which, like the
oak and hawthorn, have stems and branches increasing
in size from year to year ; or herbs like the primrose
and snowdrop, having underground root-like stems
which annually send up leaves or branches that die
off in the same year.

Distribution of Plants. Plants are found on
nearly all parts of the surface of the globe, but no
two countries have all their plants alike. They are
found in the greatest luxuriance and variety in hot
and damp climates. They are not found in the
very coldest or very dryest regions, nor at very great
depths in lakes, or the ocean. As a rule, they
diminish in size, as well as in number of kinds in pro-
ceeding from the tropics to the frigid zones ; as regards
size there are exceptions, as the gum-trees of South
Australia and the wellingtonia of California, which



I.] BOTANY.



are amongst the most gigantic of known plants ; the
seaweeds of cold seas are also far more bulky than
those of tropical regions.

Besides the plants now growing upon the surface of
the earth, the remains of many others that are no
longer living anywhere, are found in rocks at various
depths beneath it. Of these, those that lived most
recently and are hence found in the more newly
formed rocks, are like existing plants ; those that
lived longer ago are less like existing ones, and are
sometimes very different looking indeed. In short,
the longer ago the plants lived the less like they were
to plants now living : but however different are the
plants that lived longest ago, they all seem to have
grown much in the same way, to have depended on
similar conditions of light, heat, and moisture, and to
have followed the same general course of life.

The Forms of Plants are infinitely varied.
As trees, shrubs, herbs, grasses, ferns, &c., they are
familiar to all ; but only a small proportion of the
Vegetable Kingdom consists of such plants. The
bright green covering of banks, tree-trunks, damp
walls, and cottage roofs, and the carpeting of forests
and wooded valleys, chiefly consist of mosses and moss-
like plants, of which several hundred kinds grow in
Britain alone. The ocean's surface sometimes swarms
with extremely minute plants, to such an extent as to
give the water a distinct colour ; and its shores within
and beyond the tide level are covered like gardens
with sea-plants of many forms and colours. As green
and purple slimes, plants also stain damp walls, and
the rocks and stones in the bottom of fresh-water
streams and along the seashore; as leathery or
2



4 SCIENCE PRIMERS. [i.

powdery crusts they cling to the hardest rocks and
stoniest soils of mountains and moorlands ; as moulds
they spoil articles of food, books, leather-work, woollen
and other fabrics ; as dry-rot, and under many other
forms, they utterly destroy trees, wooden houses and
ships ; as smut, rust, bunt, potato- and vine-blight,
they prey upon the living tubers, stems, leaves, and
fruits of the most valuable crops, and some even
invade the organs of living animals.

Things Necessary to the Life of Plants are
air, heat above the freezing point, light, water, and
earthy (inorganic) matter in some shape. The ex-
ceptions to this are few ; amongst them are the Red-
snow plant, a most minute vegetable, which 'tinges the
surface of melting snow with a rosy hue ; and fungi,
of which some grow or are cultivated in total dark-
ness. No plants, except these, continue to live in
health in the absence of light, as a few blind animals
can do (fishes and insects) which inhabit caves, as
well as many deep-sea animals, and those that live in
the interior of others.

The Division of Labour in Plants. During
their life-time plants perform various kinds of work
which are essential, some to sustain them in life and
health, others to reproduce their kind. These kinds
of work being very different from one another are not
accomplished by any portion of the plant indiscrimi-
nately but are carried on by particular parts specially
fitted for the purpose (called organs).

In the case of flowering plants, for example, the
principal Organs are, i. The Root, by which the
plant is fixed to the ground, and absorbs /nourishment
from it; 2. The Stem, which supports the buds,



I.] BOTANY.



leaves, flowers, and fruit; 3. The Leaves, which are
usually thin and so placed as to receive as much
light as possible upon one surface ; 4. The assem-
blage of organs called the Flower; a part of this
grows into the Fruit, which contains the Seeds.

The purposes which organs are specially fitted to
serve are called their Functions. The most im-
portant of these in all plants are nourishment and
reproduction. Plants have no organs of locomotion,
or of the senses.

In Flowering Plants Nourishment is effected
by means of the root and leaves. Unlike animals,
such plants have no special stomach to receive the
food, no heart or blood-vessels to distribute it, and
no special organs to carry off what is not used as
nutriment.

The Food of plants is liquid and gaseous, never
solid. The root absorbs water, in which both gaseous
and mineral matters are dissolved ; and this fluid
ascends and enters the leaves, which also take in
carbonic acid gas from the air. By the action of
light on the water and carbonic acid in the leaves a
substance called Starch is formed, which is distri-
buted throughout the plant, supplying in great mea-
sure the material for adding to its parts.

The excess of water taken up by the root is ex-
haled by the leaves, and this tends to keep them cool.
From the starch produced in the leaves and nitro-
genous compounds taken up by the roots and dissolved
in the fluids which permeate the plant, albuminoids
are formed, which are very essential in producing
growth. These fluids further supply the materials
from which are manufactured by the plant various



6 SCIENCE PRIMERS. [i.

substances, such as resin, sugar, oil, wax, and colouring
matters,

The Reproduction of Plants takes place in
two ways. First, and principally, by seeds ; secondly
by buds that separate and grow into independent
plants. Seeds are produced by the interaction of
special organs of two kinds, and are inclosed in a
covering called the fruit. Buds that separate them-
selves and become new plants are formed on various
parts of plants, as where the leaf is attached to the
stem in the tiger-lily and the tubers or underground
branches in the potato plant.

Many plants may be artificially increased by divi-
sion ; that is, by cutting off a twig with a bud on it,
and sticking it into damp ground, when the twig will
send forth roots. Or the twig may be inserted into a
slit in the branch of a similar tree, with which it will
unite, and the bud thus nourished will grow, and pro-
duce leaves, flowers, and fruits.

The Tissues of Plants. The substance of
plants is not, like a piece of stone, made up of
particles in which no definite form or structure is
visible, but is built up of minute bags called cells, and
of tubes called vessels (which also consist at first of
rows of cells), packed more or less closely together.

The Chemical Constituents of Plants.
Plants, like animals, contain a far greater weight of
water than of anything else. Besides the elements
of water (oxygen and hydrogen), the tissues contain
carbon (which is the charcoal left after burning), and
some also contain nitrogen. Plants obtain the water
principally by their roots; the carbon by their leaves
.rom the carbonic acid gas absorbed from the air, and



I.] BOTANY.



the nitrogen in solution by the roots, from salts of
ammonia (or nitrates). Most plants contain moreover
small quantities of one or more mineral substances,
also absorbed in solution by the roots.

The green colour which prevails amongst plants
depends on the presence of a peculiar matter (Chloro-
phyll) within the cells, especially those near the surface
of the plant. This matter is coloured green only by
the action of light, consequently plants grown in quite
dark places are never green, nor are those parts of them
which are not exposed to the light (such as the roots).
The lustrous hue and glossy appearance of most leaves
is due to the fact of the coloured matter not being
superficial, but inclosed in cells whose sides are
usually as transparent as glass, and whose surface
reflects the light.

The Primary Divisions of Plants. Plants
do not present a disorderly mass of living things,
having no degrees of relationship one with another,
like children's letters or numerals emptied out of
a box ; nor are they related to one another equally,
differing in similar degrees, as one does from two,
two from three, &c. ; but they fall into groups variously
related to one another, some like brothers, others like
cousins, and so forth ; whence arises the classification
of the vegetable kingdom into sub-kingdoms, classes,
orders, genera, and species.

There are two primary groups, or Sub-kingdoms of
plants; the Flowering and the Flowerless, which
differ very much indeed ; the Flowering having,
amongst other characters, usually very conspicuous
structures commonly known as flowers, which pio-
duce seeds ; and these seeds invariably contain an



8 SCIENCE PRIMERS. [n.

independent plantlet (embryo). The Flowerless plants
(ferns, mosses, seaweeds, &c.) have no such flowers,
nor such seeds : instead of seeds they have spores
which contain no plantlet, but themselves grow into
new individuals.

Plants purify the air that is being habitually
rendered unfit to breathe by animals having already
breathed it. They provide the animal kingdom with
food, and often with shelter. They protect the
surface of the earth from being too much scorched
by the sun's rays by day, and too rapidly cooled by
radiation at night. They prevent the too rapid
evaporation of the rain-fall; and they supply man
with fuel, medicine, and many materials for arts and
manufactures.

II. GENERAL CHARACTERS OF FLOWERING
PLANTS.

1. The Vegetable Kingdom as stated above pre-
sents two quite distinct Sub-kingdoms, which the most
superficial observer rarely confounds : that of flower-
ing plants, to which trees, shrubs, and herbs belong;
and flowerless plants, such as ferns, mosses, sea-
weeds, lichens, and fungi.

The pupil is recommended to begin with the
flowering plants, not only because the two sub-
kingdoms are so different that they cannot be studied
together advantageously by a beginner in Botany, but
because the flowerless plants require for their study
high magnifying powers of the microscope and great
skill in using them.

2. Flowering plants present the following organs or



ii.] BOTANY.



parts : root, stem, leaves, flowers, which latter
are succeeded by fruit, containing seed. Most
flowering plants have roots ; all have stems, though
these may be reduced to a mere knob on the top of
the root : some few have no proper leaves, as the
dodder, and plants which, like it, feed on the juices
of others : many never have but one bud, which is a
flower-bud : but all must have a flower or flowers,
though these may be of a very simple nature.

3, The organs of flowering plants may be classed
according to their relation to one another under two
divisions : (a) an axis, of which the root is the
descending and the stem the ascending part; and
(b) appendages of the axis, which are the leaves,
and the parts of the flowers.

4. They may also be classed according to their
uses (functions) as follows : (a) for support, the
root and stem ; (b) for nourishment, the root and
leaves; (c) for reproduction, seeds, buds that
separate from the plant, flowers, fruit.

This division is evidently a very rough one ; for
while the root is often the sole organ of support,
fixing the plant to the ground and holding it upright,
other plants are supported wholly or in part by their
climbing or twining stems (convolvulus), by tendrils
(vine), by twisting leaf-stalks (clematis) and even
flower-stalks, by hooked prickles' (brambles), by sticky
glands, and in the case of water-plants by floats
containing air.

The root and leaves are the chief organs of nutri-
tion, but all green parts of the plant are so to
some extent.

The seeds are the principal means of reproducing



SCIENCE PRIMERS.



[in.



plants, but, as already pointed out, this process is also
often effected by bulbs that separate themselves (tiger-
lily) ; or by the budding of underground bulbs (onion) ;
or by tubers covered with buds (potato).



III. THE TISSUES OF PLANTS.

5. The substance or material of which a plant con-
sists is called its tissue ; and there are several kinds
of tissue. Their nature cannot be made out without
a microscope ; but as a low power will show the
most important of them, these should be learned at
once.

6. The chief is cellular tissue (parenchyma),





FIG. i Cellular tissue of rounded
cells, many times the real size.



FIG. 2. Cellular tissue of rather
long cells, many times the real size.



which forms the principal substance of most plants.
It consists of minute oval sacs, called cells, crowded
together and often becoming angular by pressure
(Figs i and 2). Orange-pulp is an example of cells
loosely packed together ; cork and elder pith of cells
crowded together which have always been cohe-
rent by their sides. The walls of the sac consist



in.] BOTANY. II

usually of a very thin and transparent membrane,
which may contain air only, when the cells are dead
(as in pith) ; or a fluid, as in the cells of orange-pulp ;
or, besides fluid, granules of protoplasm (Par. n),
coloured by substances which are green in leaves, and
of other tints in many flowers; or granules of starch.
Sometimes the cell-wall is very thick and hard, as in
the stone of the cherry and other stone-fruits, and the
leathery surface of leaves such as those of the stone-




FIG 3. Thick- walled cells from a leaf of stone-pine as seen in a cross-cut,
many times the real size.



pine (Fig. 3). Some plants are formed wholly of
cellular tissue (mosses, fungi, seaweeds, lichens), and
almost all plants have more cellular than any other
tissue. Fluids can pass through the walls of the cells,
and the nourishment which is sucked up by the roots
in the fluid state, is distributed through the plant chiefly
by passing from cell to cell. The celte which cover
the surface of the plant are a good deal flattened, and
form a layer called the epidermis.

7. Wood-tissue, of which in addition to vessels



12



SCIENCE PRIMERS.



[in.



wood is principally formed, consists of long cells, or
rather tubes, tapering and closed at both ends, with
thick walls, and which lie side by side and form wood.

8. Bast-tissue consist of very long flexible cells,
or rather tubes, also closed at both ends. It occurs
chiefly in the inner bark, and supplies the materials of
many useful fabrics. Hemp and flax are bast-cells
of the plants of those names ; and the Bast, used by
gardeners for tying, is the inner bark of the lime-tree.

9. Vascular tissue consists of long, unbranched
tubes, with thin walls, which are often dotted or




FIG. 4. Spiral-vessels with cellular tissue on each side, many times the
real size.



barred, and sometimes thickened internally by spiral
threads, easily seen in the leaf of the hyacinth, if
broken across. These are called spiral vessels (Fig.


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