the petiole or leaf-stalk is generally cylindrical, but frequently
triangular, and in grasses it is flat and surrounds the stem, this is
called a sheath; when leaves are narrow and not expanded into a lamina,
as in the pine tribe, they are said to be "acicular."
The stalks which bear the flowers are called "pedicels," at the base of
which are a pair of scales called "bracts;" when these are large and
expanded, so as to enclose the flowers, they are called "spathes" (this
is seen in the arum), and when there are a number of flower-stalks
arising from one point the bracts there collected are called an
"involucre." A flower consists of several parts, the outermost green
scales, composing a set, are called the calyx, and each part of it, is
called a "sepal," within this is the "corolla" or that coloured part
which forms the most characteristic feature of the flower, each part of
the corolla is called a "petal;" when the corolla consists of but one
piece, it is called "monopetalous," and when of many, "polypetalous."
The forms of corolla vary according to the form and the mode in which
the petals are placed, whether united or separated, and to what extent,
whether regular or irregular; the most usual forms are the following:--
[Illustration: Campanulate (Bell-shaped), Canterbury Bell.
Rotate (Wheel-shaped), Woody Nightshade.
Hypocrateriform (Salver-shaped), Phlox.
Infundibuliform (Funnel-shaped), Tobacco.
Labiate (Having Lips), Bugle.
Ringent (Grinning), Sage.
Galeate (Helmet-shaped), Monk's-hood.
Pappilonaceous (Like a Butterfly), Sweet Pea.
Cruciate (Like a Cross), Cuckoo-flower.]
Within the corolla are placed the "stamens" (male reproductive organs)
these consist generally of two parts, the head and stalk, the former
called the "anther" and the latter the "filament," which last is
sometimes absent, and the anther is said to be "sessile;" on the
surface of the anther is the "pollen" or fertilising dust.
Within the centre of the flower is the "pistil" (female reproductive
organ), this consists of one or several cells called "ovaries," from
the pistil a tube rises, having an expanded end called the "stigma,"
it is by the application of the pollen dust to this stigma that the
ovaries are fertilised, and the various insects, especially bees,
who seek for honey, shake off by their movements the pollen from the
anthers and cause it to be applied to the stigma, thus unconsciously
performing a necessary office for the plant while they rob it of that
only which is not required.
The stamens are sometimes separate, sometimes bound up into one or
more bundles, and are placed in various situations, names are given to
describe such arrangements as follows:--
Stamens in one bundle, Monadelphous.
Stamens in two bundles, Diadelphous.
Stamens in more than two bundles, Polyadelphous.
Filaments placed directly below the pistil, Hypogynous.
Placed upon the sides of the calyx, Perigynous.
On the sides of the corolla, Epipetalous.
On the top of the ovary, Epigynous.
When the ovaries are fertilised the flower dies and they begin to
enlarge and ripen to form the fruit, which is the pistil enlarged, and
contains the ovules ripened into seeds.
The fruits of different plants are known by various names according
to the state of development of the various parts composing them. If
the ripe fruit split open so as to let out the seeds (as in the common
pea) it is called "dehiscent," if it do not so split (as in the apple)
it is said to be "indehiscent;" the outer part of fruit is called the
"pericarp," and this may be soft and fleshy as in the apple or cherry,
or hard as in the filbert. The following are the names of the principal
varieties of fruit:--
[Illustration: Pome (Apple).
Gland (Acorn).
Legume (Pea).
Stobule (Hop).
Drupe (Plum).
Berry (Currant).
Capsule (Poppy).
Siliqua (Shepherd's Purse, Wallflower).
Eterio (Strawberry).
Nut (Hazel-nut).
Caryopsis (Wheat).]
The seed is the ovule ripened, it contains the germ of the future
plant, called the "embryo," the outer part of the seed is called the
"testa," and the space between this and the embryo is generally filled
with starchy matter called the "albumen." The embryo consists of the
plumule or stem, the "radicle" or root, and the cotyledons or leaves
of the future plant; when the seed has but one cotyledon it is called
"monocotyledonous" and when it has two "dicotyledonous."
Flowers are arranged in various ways upon the plants which produce
them, and receive names accordingly; the whole arrangement of flowers
is called the "inflorescence."
The following are the principal forms of inflorescence:--
[Illustration: Hemlock.]
The UMBEL, in which all the flower-stalks (pedicels) radiate
from one point, as in the carrot (daucus carota). Umbels are sometimes
compound, that is, the flowers are placed in umbels at the end of
stalks themselves radiating from a point and so forming an umbel, as
in the Hemlock (Conium maculatum).
[Illustration: Plantain.]
The SPIKE, is that kind of infloresence in which all the
flowers are seated without stalks upon a general peduncle or axis, as
in the Plantain (Plantago media), in which the spike is entire, or as
the Lavender (Lavandula Vera), in which the spike is interrupted, that
is, the inflorescence is not continuous.
[Illustration: Hazel]
CATKIN, or AMENTUM, is the same as a spike, but
in which the flowers are imperfectly developed, as in the Hazel
(Corylus), Willow (Salix), White Poplar (Populus Alba), &c.
[Illustration: Water-cress]
The RACEME has the inflorescence placed along a common
axis or centre, the same as a spike, but with the flowers placed
upon stalks instead of being sessile, as in Water-cress (Nasturtium
officinale) and Red Currant (Ribes rubrum).]
[Illustration:Candy-tuft]
The CORYMB is a form of inflorescence pretty much the same as
raceme, but the flowers of which proceed upwards till they are all on
a level, as in Candy-tuft (Iberis).
[Illustration: Creeping Soft Grass.]
The PANICLE, the same as the raceme, but having the flower
stalks themselves divided into branches, as in Creeping Soft Grass
(Holcus mollis). This and the spike are the most usual form of
inflorescence found among grasses, in many of which the panicle,
however, is often contracted almost to a spike.
[Illustration: Elder.]
The CYME, this resembles the panicle shortened in such a
manner as to become flattened or almost corymbose, as in the Elder
Tree (Sambucus nigra), in which there are five principal stalks of
inflorescence.
[Illustration: Chamomile.]
CAPITULUM, in which the flowers arise from a broad round head
or receptacle as in the composite flowers, such as Chamomile (Anthemis
nobilis); in such flowers the star-like ray of florets are called the
florets of the ray, and those composing the centre the florets of the
disc.
[Illustration: Arum.]
The SPADIX is that form of inflorescence in which the
expanded bract, called a spathe, forms a sort of sheath inclosing
the flowers. This spathe is white in the example given, and is often
mistaken for part of the flower itself, as in the Wake-robin or Arum
(Arum maculatum).
The vegetable kingdom is divided into three great natural families, the
Acrogenæ, the Endogenæ, and the Exogenæ.
The acrogenous plants are those which as a general rule have neither
branches, leaves, nor flowers; they are almost wholly made up of
cellular tissue, and are many of them so minute that they are quite
invisible individually to the unassisted eye, and are among the most
wonderful works of the Creator, having an amount of beauty in form and
elaboration of ornament bestowed on them, quite equal to anything among
the higher and larger creations, and yet some of these are so small
that tens of millions may be placed in the space of a cubic inch, of
such are the Diatomaceæ and Desmidiaceæ.
The acrogens take an immense range in the scale of organisation,
from the ferns (which appear but little inferior to the exogenæ or
endogenæ, have stems and leaves, and in some cases, as in hot and moist
climates, assume the size and form of a tree), to the very lowest
state of vegetable existence, consisting of simple cells uniting into
strings or forming simple threads, such as the green algæ which form
on stagnant waters and damp ground or wood-work, and the mould or
mildew which forms on all decomposing substances. The general name for
these acrogens, "cryptogamia," which has been in use for a long time
and is commonly still used, indicates that the reproductive organs
are invisible, hence the expression used by one of Shakespeare's
characters, "We have the secret of fern seed, we walk invisible;"
but this is not really the case, for the "sorri" at the back of
fern-leaves, are vessels filled with spore cases each having a number
of angular seeds within it; the lower tribes of the acrogens do not
commonly grow from seed but by an extension of their several parts by
the development of the cells of which they are composed, and by their
separation into portions.
Few of this tribe have anything like true woody texture, except their
highest order, the ferns, which form some of the most beautiful
objects in the vegetable world. Few of the family of acrogens are of
much direct use to man, the mushroom tribes are very generally eaten
where they abound, the lichens of the arctic regions form the food
of the reindeer (the greatest friend of man in these cold climes) as
well as, in part, the food of man himself; but although these lowly
plants serve man but little, directly, there is not a shadow of doubt
that they have as important an office to fulfil as any other family
or tribe of organised creatures, whose purpose may meet the eye more
plainly. For all the members of creation form, as it were, the links of
one great chain, and were but one removed, though it might perchance
be only some poor weed or lowly moss, yet might it cause the whole to
be annihilated; for certain earthy matters enter into the structure
of all plants, and it appears to be the wonderful office of some of
these lowest tribes of plants to prepare this earthy matter for its
reception into the systems of higher organisms, for as silica is one
of the primitive rocks of the earth and is only found in fragments,
from the largest to the sand on the sea-shore, which is nothing but a
collection of minute fragments of quartz worn small by attrition, yet
a grain of sand is a gigantic mass of rock in comparison with the thin
porous hollow shells of the Diatomaceæ, &c., and by far too large to
be absorbed or dissolved so as to be taken into the systems of other
plants that may require it, which plants would cease to exist if this
earth were not thus prepared for them; now these are the corn-bearing
plants, the most useful to the animal world, and upon which it in
reality depends for existence. Moreover the whole of the mould in which
the higher orders of plants grow, is formed by the decomposition of the
more humble grades, especially the lichens, which first take possession
of the surface of bare rocks and stones, and furnish by their death
food fit for the sustenance of those which follow them. Like the higher
orders of vegetation, these minute plants excrete oxygen, and thus in
the ocean may supply this vital element for the respiration of the
various corresponding minute animal organisms which inhabit the depths
of the sea and which cannot come to the surface to get it, so that the
two thus supporting each other, form food for all the higher marine
animals, which are finally eaten by man. So that upon some of these
minute and apparently useless creatures hang the lives and well-being
of many of the most important vegetables and animals.
Dr. Lindley divides the acrogens into the following orders:--
1. ALGÆ (Algals), including Sea-weeds, &c.
The Algæ include the lowest of all the vegetative organisms, the
"Protophytes" (first plants). These have no individual parts, but
consist of living cells, propagating by sub-division or by the union
of two cells into one, causing the formation of "nuclei" or smaller
cells within them, each of which becomes a parent cell after the
rupture of the cell-membrane which contained them.
Dr. Carpenter, in his "History of the Microscope," says:--"The
life-history of one of these uni-cellular plants in its most simple
form, can scarcely be better exemplified than in the _Palmogloea
macrococca_, one of those humble forms of vegetation which spreads
itself as a green slime over damp stones, walls, &c. When this slime
is examined with the microscope, it is found to consist of a multitude
of green cells, each surrounded by a gelatinous envelope; the cell,
which does not seem to have any distinct membranous wall, is filled
with granular particles of a green colour, and a 'nucleus' may
sometimes be distinguished through the midst of these. When treated
with tincture of iodine, however, the green contents of the cell are
turned to a brownish hue, and a dark-brown nucleus is distinctly
shown. Other cells are seen, which are considerably elongated, some
of them beginning to present a sort of hour-glass contraction across
the middle; in these is commencing that curious _multiplication by
duplicative subdivision_ which is the mode in which increase nearly
always takes place throughout the vegetable kingdom."
[Illustration: Fucus Vesiculosus.]
The higher tribes of Algæ embrace the sea-weeds; these are for the
most part broad, leaf-like expansions of "thallus," composed of
cellular tissue, they sometimes grow to an enormous length. Humboldt
mentions the sea-grass as extending for miles, and forming continuous
extensions of two or three hundred feet, and the _Macrocystis
pyrifera_ attains to the length of more than a thousand. The common
Bladder-wrack (_Fucus vesiculosus_) was formerly much used to procure
soda from, its ashes containing a considerable quantity, it is also
used for manure; the _Laminaria digitata_ is eaten under the name of
"tangle," and a nutritious jelly is made from the "Carigeen moss"
(_Chondrus crispus_).
2. CHARACEÆ (Charas).
These are a kind of fresh-water Algæ, composed of tubes of cellular
tissue; they are peculiar, from the fact that the spores of the plant
have cilia, giving to them the powers of motion and enabling them to
swim away and spread the plant afar off. It is in the Charas that the
peculiar circulation of the granules of "endochrome" called "cyclosis"
is best seen.
[Illustration: Charas.]
3. FUNGI (Fungals), including Mushrooms, &c.
[Illustration: Eatable Mushroom (Agaricus campestris).]
The Fungi comprise a great variety of vegetable growths, from the
mould which grows on any animal or vegetable substance, to the
mushroom. Some of the moulds or mildews found on various decaying
substances are peculiar to them, and in many cases exceedingly
destructive. The microscopic fungus _Puccinea graminis_, is the
parasite which fixes itself to corn and produces the disease known
as mildew, and the _Uredo segetum_ (another microscopic fungus)
causes the "smut;" the "bunt" is caused by the _Uredo foetida_,
and the "spur," or "ergot," which attacks rye, is caused by the
_Acinula clavis_. These fungi completely destroy the grain of corn,
in which they form, and propagate in the most rapid manner; the
ergot is moreover a dangerous poison to those who eat the bread made
of rye infected by it. The Truffle (_Tuber cibarium_) is a kind of
underground fungus, and is esteemed a dainty. Mushrooms are also
fungi, and several species are sufficiently wholesome; these are the
Field Mushroom (_Agaricus campestris_) and the Fairy-ring Mushroom
(_Agaricus pratensis_).
4. LICHENES (Lichens),
Are those dry scaly growths forming grey, green, or yellow spots
on the barks of trees and in various other places, and they grow
in a sort of leaf or scale called a "thallus." They are used as
articles of food and as "dye-stuffs;" the _Cetraria Icelandica_ is
the "Iceland Moss" used here for making a sort of nutritious drink or
jelly, the natives of Iceland, however, use it as common food; the
_Cladonia rangifarina_, or Reindeer Moss, is the chief food of that
useful creature which forms the whole property of the Laplander; and
the _Roccella tinctoria_ is the substance from which the dye called
"archil" is procured.
[Illustration: Lichen.]
5. FILICES (Ferns).
The Ferns are a very numerous order of acrogenous plants, growing in
the temperate regions from a rhizome or underground stalk (commonly
called its root), which throws up "fronds" or leaves with a strong
midrib; this midrib is commonly called its stalk, but in tropical
countries the fern stalk rises above ground to the height of 30 or 40
feet, and then it is seen that the ordinary stalks are but the midribs
of the fronds. There are between two and three thousand species of
fern. The fronds open in a peculiar manner, unwinding as it were from
a round ball. The "sorri" or seed-cases are situated at the back of
the fronds in little brown spots, each of which is found to consist of
a heap or collection of round capsules, and if these be placed under
the microscope they have the appearance of little membraneous cases
covered with net-like markings, and at the upper part a striated band
of a brown colour, which after a time stretches out into a nearly
straight line, tearing open the bag or capsule, and a number of seeds
escape. Ferns grow best in damp and shady situations, and will thrive
well in damp mould under a glass case.
[Illustration: Fern.]
6. MARCHANTIACEÆ (Liver-worts).
[Illustration: Liver-worts.]
These Liver-worts are much like Lichens, growing between and upon
stones near springs and moist places, and forming a broad thallus
or root from which grow cup-shaped sporangia or seed-cases. The
_Marchanta polymorpha_ is one of its chief members.
7. JUNGERMANNIACEÆ (Scale-mosses).
[Illustration: Scale-moss.]
The Scale-mosses grow in moist places and under the stems of trees and
plants. Their appearance is scaly, and they have a sort of stalk.
8. BRYACEÆ (Urn-mosses).
[Illustration: Urn-moss.]
Urn-mosses comprise the most ordinary of the mosses, the "Brium,"
which grows on the ground everywhere, forming tufts; its
fructification resembles an urn, and hence its name.
9. LYCOPODIACEÆ (Club-mosses).
[Illustration: Club-moss.]
These are very beautiful mosses, of a bright green colour, growing in
moist places. There are about 200 species of club-mosses known. The
common Lycopodium is its most characteristic member. It grows well
with ferns under a glass case.
10. EQUISETACEÆ (Horsetails).
The Equisetaceæ are the highest of the Acrogens, and nearly resemble
the Endogens; they grow in ditches and pools, have a hollow stem
with joints at regular intervals from each of which a whorl of green
modified leaves arises; they are very full of earthy matter (silica),
and one kind (_Equisetum Hyemale_), called Dutch Rush, is so rough
with it that it is used for polishing and scraping many articles.
[Illustration: Horsetail.]
The second division of the vegetable kingdom are the Endogenæ, which
are those plants growing from a central bud only, as the palms,
bamboos, and canes of all kinds, the grasses and all graminiferous or
grain-bearing plants, as wheat, barley, &c. They have but one cotyledon
in the seed and have no bark, but in place thereof a kind of natural
varnish or thin coating of silica; this varnish or external polish is
seen in the stalks of corn and on canes. Their leaves are often of
great size, the veins run parallel to each other (fig. 8), they often
grow from an expanded base which surrounds the stalk as in corn, and
branch off at regular intervals making knobs or joints, as may be seen
in the bamboo cane (figs. 9 and 10), in other cases they branch off
spirally, and when fallen form a sort of trellis-work on the stem (as
in some of the palms) but always in a regular manner. The wood of this
family of vegetables has the same porous structure as cane (figs. 11,
12, 13,14), and is often hollow in the centre, becoming more and more
solid according to the age of the tree. The stems of these plants are
limited in growth and soon acquire their full size, which never exceeds
eighteen or twenty inches in diameter although some of the palms are
nearly 150 feet high. When the stem has acquired its full size, the
continual production of more woody fibres makes it impossible that
these (like the exogenæ) can have a very extended period of existence,
for when every part of the stem is full of woody matter, the plant
ceases to grow from obstruction to the circulation of the juices. The
stems of some of this family are always hollow like the stalks of corn;
this arrangement allows of great elevations without bending, and is
found to be the form which gives the greatest strength from a given
quantity of material--one of those beautiful mechanical perfections of
nature which man first admired and then endeavoured to imitate.
[Illustration: FIG. 8.--ENDOGENOUS LEAF, SHOWING PARALLEL VENATION.]
[Illustration: FIG. 9.--BAMBOO CANE, SHOWING JOINT.]
[Illustration: FIG. 10.--BAMBOO CANE, SPLIT OPEN.]
[Illustration: FIG. 11.--PERPENDICULAR SECTION OF ENDOGENOUS WOOD.]
[Illustration: FIG. 12.--PART OF THE SAME, MAGNIFIED.]
[Illustration: FIG. 13.--TRANSVERSE SECTION OF ENDOGENOUS
WOOD.]
[Illustration: FIG. 14.--PART OF THE SAME, MAGNIFIED.]
Some of the palms and other endogenæ are of a most beautiful form,
and are moreover quite as useful as beautiful, furnishing food to
the inhabitants of many regions, especially the Arabs of the Desert,
who carry the dried fruit of the Date-palm with them, on crossing
these vast plains of sand, as their chief food. The Plantain (_Musa
sapientum_) forms a most beautiful and graceful object, with its
enormous leaves springing up from the ground by their midrib in
clusters, and extending upwards for 20 or more feet in graceful curves,
affording a shady and cool retreat beneath them from the burning rays
of the sun; the fruit is also one of the necessaries of life in the
regions where they abound. The Fan-palm is another beautiful specimen,
from the fan-like leaves of which the punkahs or Indian fans are made.
The Palmyra palm furnishes leaves which are used to thatch houses, the
sap is drunk as a refreshing beverage, and when evaporated yields a
kind of sugar called "juggery," from which palm-wine is made.
The palms were amongst the first trees created, their fossil stems
being constantly found; they were even then associated with the
elephant and rhinoceros, and although these are found chiefly in the
northern parts of Europe, yet it is much more reasonable to suppose
that the climate of these parts has changed, than that these two
favourites of the sunny regions should have had their natures changed.
Among the useful members of the endogenæ may be mentioned the Maranta
Arundinaceæ, or Arrow-root plant, which is thus described by Dr.
Baird:--"It is a genus of monocotyledonous plants, belonging to the
natural order Cannaceæ or Marantaceæ, and composed of herbs which have
a well-developed rhizome or tuberous root containing a large quantity
of fecula or starch. The species are natives for the most part, of
tropical America, a few being also found in India. The structure of the
flowers is remarkable, and the fruit fleshy. The most important species
is the Maranta Arundinaceæ, a plant which is extensively cultivated in
the West Indies, the southern parts of the United States, and in the
Isle of France, for the sake of its root, which affords the substance
so well-known as Arrow-root. This root consists of a tuber of a
peculiar form, and contains a large proportion of fecula; the stem is
upwards of three feet high, and the flowers are white, delicate, and
small. In Cayenne the tubers are eaten by the natives, roasted, as a
cure for intermittent fevers, and when bruised, are applied by them
to wounds, and considered more especially as a specific against those
caused by poisoned arrows, hence the name of Arrow-root."