at large in his work "On the Different Forms of Flowers," a large
proportion of existing plants are fertilized by the action of the
wind; and again, many plants bear two kinds of flowers, the one
conspicuous and attractive to insects, the other inconspicuous and
which never open to admit the activity either of insects or of the
wind. Moreover, there are various other agencies called into play.
Some plants, such as the _Hypericum perforatum_, one of the
commonest of the St. John's Worts, and probably the bindweed, are,
it seems, fertilized by the withering of the corolla, which naturally
brings the stamens into contact with the style, and so transfers the
pollen grains from the one to the other.[8] Other plants, again,
such as the common centaury (_Erythræa centaurium_) and the _Chlora
perfoliata_, are fertilized by the closing of the corolla over the
anthers and stigma, not in the death but in the sleep of the plant.[9]
In the brilliant autumnal _Colchicum_, and in the _Sternbergia_,
again, according to Dr. Kerner, Nature has recourse to a more complex
machinery: the corolla first closes over the anthers, which are at
a lower level than the stigma, and takes off some of the pollen; a
growth of the corolla carries the pollen dust to the level of the
stigma, and a second closing of the corolla transfers the pollen
to the stigmatic surface. The pollen has been made to ascend to its
proper place by an arrangement which reminds one of the man-engine of
a Cornish mine.[10] A similar arrangement is described as occurring in
the bright-flowered _Pedicularis_.[11]
Let us take another group of beautiful flowers which adorn our
greenhouses and our tables: I mean the _Asclepiadæ_, to which the
_Stephanotis_ and the _Hoya_ belong. The former is distinguished
by the beauty of its scent as well as of its flowers. Both present
flowers not merely conspicuous in themselves from their size, form,
and colour, but conspicuous also by reason of their grouping. Here,
if anywhere, we should expect that beauty should justify itself by its
utility. But the facts appear to be just the other way. The pollen
is collected together into waxy masses, which are arranged in a very
peculiar manner on the pistil; and the pollen tubes pass from the
pollen grains whilst still enclosed within the anthers, and so bring
about fertilization without the intervention of insect agency. It is
difficult to suppose the _Asclepiadæ_ can have become beautiful for
the sake of an agency of which they never avail themselves.
Our common Fumitory has not very conspicuous flowers, but still they
have considerable attractiveness of form and still more of colour, due
both to the individual blossom and to their grouping together; and yet
_Fumaria_ is said to be self-fertile.[12]
A much more brilliantly coloured member of the same family is the
_Dicentra (Diclytra) spectabilis_, so familiar in our gardens. Any
one who examines the flowers of this species will continually find the
pollen grains transferred to the stigma without the slightest trace
of the flower ever having opened so as to allow of insect agency.
Dr. Lindley[13] has given an account of the mechanism for
self-fertilization; and this flower has recently been the subject
of an elaborate study by the German botanist, Hildebrand,[14] and
he concurs in the view that the anthers inevitably communicate their
pollen to the pistil, and that as the result of a very complicated and
subtle arrangement of the parts, which it would be useless to attempt
to describe without diagrams. But he believes that in addition to the
arrangements for self-fertilization, another arrangement exists for
producing cross-fertilization by insects; but as the plant has never
produced seed under his observation, he is unable to tell whether
one mode of fertilization is more useful than the other. I think the
evidence of the self-fertilization is far clearer than that of the
cross-fertilization.
Now, if the _Dicentra_ has become beautiful in order to attract
insects, it must have done so through a long series of developments,
for its adaptation to their agency is of the most complex kind. It is
difficult to suppose either that, side by side with this development
for cross-fertilization, there has been also developed another
complex arrangement for self-fertilization, or that an earlier complex
arrangement for self-fertilization should have survived through the
changes necessary to render the flower fit for insect fertilization.
The co-existence in one organism of two complex schemes for different
objects, and the interlacing of those two schemes in one beautiful
flower (which, if Hildebrand be right, occurs in the _Dicentra_), seem
to be things very improbable if the beautiful flower has become what
it is in the pursuit of one only of those objects. These speculations
may be premature as regards the particular flower; but the
co-existence of two modes of fertilization is not peculiar to
_Dicentra_ and seems to furnish material for important reflection.
Yet one more plant must be considered. The _Loasa aurantiaca_ is
a creeper which grows freely in our gardens, and has large and
brilliantly coloured scarlet flowers turned up with yellow. Its
seeds set freely in cultivation. The means by which fertilization is
effected are--unless my observations have misled me--very peculiar.
When the flower first unfolds, the numerous stamens are found
collected together in bundles in depressions or folds of the petals;
after a while the anthers begin to move, and one after the other the
stamens pass upwards from their nests in the petals, and gather in
a thick group round the style; subsequently a downward and backward
movement begins, which brings the anthers against the pistils, and
restores the stamens nearly to their old position, but with exhausted
and faded anthers. I have never seen any insects at work on the
flowers, and yet I find the plant to be a free seeder.
So long ago as 1840 M. Fromond enumerated several conspicuous flowers
in which, according to his observations, fertilization was effected
without the agency of either the wind or insects.[15] And much more
recently an American writer, Mr. Meehan, has given a list of eleven
genera, amongst others, in which he has observed the pistils covered
with the pollen of the plant before the flower has opened, and in the
one case which he submitted to the microscope, it was found that
the pollen tubes were descending through the pistil towards the
ovarium.[16] Amongst the genera he names were _Westaria_, _Lathyras_,
_Ballota_, _Circes Genista_, _Pisum_, and _Linaria_.
The instances which I have given are mostly from plants familiar
in our fields, our gardens, or our greenhouses. They are, I think,
sufficient to make us pause before we conclude that all conspicuous
flowers are fertilized by insect agency. It may be that Bacon's
warning to attend as carefully to negative as to affirmative instances
has been a little forgotten. Moreover, these instances seem to
show that it would be a great error to suppose that all flowers are
fertilized either by insects or by the wind; and it is probable
that the more the subject is considered the more complex will the
arrangements for fertilization be found to be.
The agencies to which I have last referred exist, it will be observed,
in beautiful and conspicuous flowers; and yet act independently of
that beauty and that conspicuousness: so that in each instance
these facts are, on the utilitarian theory, unexplained and residual
phenomena. They, therefore, demand earnest inquiry. For the existence
of a single residual phenomenon is notice to the inquirer that he has
not got to the bottom of his subject; that his theory is either not
the truth or not the whole truth.
Do the facts justify us in concluding that insect fertilization is
more beneficial to the plant than fertilization by the wind or any
other agency? Do they afford any sufficient cause for that change from
the one mode of fertilization to the other which has been suggested?
The facts bearing on these questions are very remarkable; for, as we
have already seen, many plants produce two kinds of blossom, the one
conspicuous and the other inconspicuous; the one visited by insects,
the other self-fertilizing. Recent observation shows that these
cleistogamous flowers, as they are called, are present in a great
variety of plants.[17] In the violet they are found to exist, being
seen in the summer and autumn, when all the more brilliant flowers
have gone. The one flower has everything in its favour--honey and a
beauty of colour and of smell that has passed into a proverb--and it
opens its blue wings to the visits of the insect tribe in the season
of their utmost jollity and life. The other has everything against
it: it is inconspicuous, scentless, ugly, and closed. And yet, which
succeeds the better? which produces the more seed? The cleistogamous,
and not the brilliant flowers: the victory is with ugliness, and not
with beauty.
The same is true of the _Impatiens fulva_. This is an American plant,
closely akin to the balsam of our gardens, which has now thoroughly
established itself on the banks of some of our rivers, as the Wey,
and the tributary stream that runs through Abinger and Shere. It has
attractive flowers hung on the daintiest flower-stalks. It has also
little green flowers that never open and almost escape attention;
and yet they, and not the large flowers, are the great source of seed
vessels to the plant--the great security that the life of the race
will be continued.[18] Again, ugliness has borne away the palm of
utility from beauty.
So, too, in America the same happens with the _Specularia perfoliata_:
in shady situations all its flowers are said to be cleistogamous, and
to be wonderfully productive and strong.[19]
The conditions of the problem in these cases are such as to make them
of the last importance in our inquiry into the utility of beauty;
for in each case we are comparing a conspicuous and an inconspicuous
flower in the very same plant. The conditions seem to exclude the
possibility of error in the result.
Two explanations have been suggested of the origin of these
cleistogamous flowers: according to the one, they are the earliest
form of the flowers; according to the other view, they are degraded
forms of the more beautiful flowers.[20] For our purpose, it is
immaterial whether of the two explanations is correct; for either the
development of beauty has diminished the utility of the flower, or the
loss of beauty has increased the utility: in either event, utility and
beauty are dissociated the one from the other.
Another experiment Nature presents us with, in which the conditions
are nearly, if not quite, as rigorously exclusive of error. The vast
majority of orchidaceous plants are, as already mentioned, dependent
on insect agency, for fertilization, and present a marvellous variety
of contrivances for effecting cross-fertilization through their
activity. But one of our orchids (the Bee orchis) is self-fertilized.
I hardly know anything in vegetable life more striking or beautiful
than to see its delicate pollinaria at a certain stage of its
inflorescence descending on to the stigmatic surface and so yielding
their pollen grains to the fertilization of their own blossom; and yet
the Bee orchis has been found by observers to be as free a seeder as
any of its tribe. Here the beauty and conspicuousness of the blossom,
which are very great, are, as far as can be seen, useless; the plant
gains nothing by the attractiveness which it offers, and the colouring
and ornamentation of the blossom are, on the theory of utility,
residual phenomena.
It is difficult to imagine that the change from wind or
self-fertilization can, so to speak, commend itself to the flower on
the score either of economy or success. If the anemophilous blossom
must produce somewhat more pollen than the entomophilous, it saves
the great expenditure of material and vital force requisite for the
production of the large and conspicuous corolla. The one is fertilized
by every wind that blows; the other, especially in the case of
highly-specialized flowers like the orchids, may be incapable of
fertilization except by a very few insects. The celebrated Madagascar
orchid _Angræcum_ can be fertilized, it is said, only by a moth with
a proboscis from ten to fourteen inches long--a moth so rare or
local that it is as yet known to naturalists only by prophecy. It
is difficult to suppose that it would be beneficial for the plant's
chance of survival to exchange as the fertilizing agent the universal
wind for this most localized insect.
And here another line of evidence comes in and demands consideration.
The face of Nature, as we now see it, has not been always exhibited
by the world. The flora, like the fauna, of the world has changed: how
has it changed as regards the beauty of the flowers? Does it give any
testimony to that _becoming_ beautiful of the flowers of plants to
which Mr. Darwin refers? The answer is not a very certain one,
by reason of the imperfection of the geological record, of the
probability that beautiful plants, if they had existed, and had been
of a delicate structure, would have perished and left no trace behind.
But so far as an answer can be given, it is in favour of the increase
of floral beauty in the vegetable world. The earliest flower known
(the _Pothocites Grantonii_) occurs in the coal measures; its flowers
cannot have been other than inconspicuous in themselves, though it is
possible that by grouping they were made more attractive to the eye;
in the period of the growth of the coal, when this plant lived, the
vast forests seem principally to have been composed of trees without
conspicuous blossoms, huge club mosses and marestails, and many
conifers; in the earlier periods of this earth we have no trace of
conspicuous blossom, and it is not till the upper chalk that the oaks
and myrtles and _Proteaceæ_ appear as denizens of the forests. In like
manner, if we refer to the appearance of insects on the earth, we have
no clear trace in very early strata of those classes of insects
which now do the principal work of fertilization for our conspicuous
flowers. In the coal measures there have been found insects of the
scorpion, beetle, cockroach, grasshopper, ant, and neuropterous
families; but of a butterfly or moth there is only evidence of great
doubt. It seems probable, then, and one cannot say more, that with
the progress of the ages, flowers, as a whole, have become more
conspicuous and attractive. But if we inquire whether the dull flowers
of one era have grown into the conspicuous flowers of another, the
answer is negative. The conifers of the coal age were anemophilous
then, and are anemophilous still; they show no symptom of becoming
more conspicuous; the same is true of the oaks of the chalk period,
and of all other inconspicuous plants. The difference between
conspicuous and inconspicuous flowers appears a permanent one; and the
page of geology gives no evidence in favour of the supposed change.
Another observation must yet be made. Comparing flowers fertilized
by insects and by the wind, it has never, so far as I can learn,
been observed that the former are more certain of being set or more
prolific than the latter; and, as already shown, the inconspicuous
flowers are often more fertile than the conspicuous ones. What motive
would there be, then, for the inconspicuous flowers of the early
geologic periods to convert themselves into the brilliant corollas of
our day?
Carefully considered, the passage which I have cited from Mr. Darwin
does not account for the beauty of the flowers of plants at all; it
accounts only for their conspicuousness, as the writer himself points
out; and the two things are so different, that to account for the one
is not even to tend to account for the other. If any one will consider
the beauty of every inflorescence, whether conspicuous or not--a
beauty which the microscope always makes apparent where the unaided
eye fails to perceive it; or, again, the easily perceived beauty of
many inconspicuous plants; or, lastly, the beauty of many conspicuous
plants which does not tend to their conspicuousness--he will see how
true this is.
For in many conspicuous flowers there are delicate pencillings and
markings which certainly do not tend to make them such, but which
nevertheless add greatly to their beauty, as we perceive it. In the
regularly shaped flowers these markings often start from the centre
of the blossom like radii, and they may be conceived as guiding the
insects to the central store of honey. Such guidance can hardly be
needful, as the shape of the flower itself generally does all, and
more than all, that the markings can do in the way of guidance. But
it is by no means true that all the markings lead to the centre of
the flower: many are transverse; many are marginal; some are by way of
spot.
Again, take the irregularly shaped flowers, which are supposed to be
the exclusive subjects of insect fertilization; how infinite are the
beauties of the flower over and above those which make it conspicuous,
or can assist to guide the insect. Take the orchids, for example: the
labellum is generally the landing-place of the insect visitors; but
the other flower-leaves are almost always the subjects of a vast
display of delicate beauty which cannot be accounted for by the
necessity of conspicuousness or guidance. All this beauty is, on the
theory in question, an unexplained fact.
But, again, take the grasses, which depend for fertilization
exclusively on the wind, and have no need to woo the visits of the
insects. The beauty of the markings of the inflorescence of many
of the grasses is very great, though far from conspicuous: take
the delicately banded flowers of our quaking grasses; take the rich
crimson of the foxtails; take the brilliant yellow of the Canary
_Phaleris_; and it is impossible to refuse the attribute of beauty in
colour to the wind-loving grasses. And all this beauty is unexplained
on the theory in question.
It is impossible to speak of the grasses and not to have the mind
recalled to the beauty that resides in form as contrasted with colour.
Elegance, grace of form, characterizes most (but not all) plants,
whether fertilized by the wind or by insects; and yet this grace, in
many cases, perhaps in most, adds nothing to their conspicuousness. It
is, on the theory in question, a piece of idle beauty; and yet it is
all-pervading--a persistent, though not universal, characteristic of
the vegetable world.
But to revert to conspicuousness. It is not true to say that all
self-fertilized plants have inconspicuous flowers. I have adduced the
_Stephanotis_ and _Hoya_ on this point. Nor is it true to say that all
anemophilous flowers are inconspicuous as compared with the green of
their leaves. The large but delicate yellow groups of the male flowers
of the Scotch pine (not to travel beyond very familiar plants) are
very conspicuous in the early summer--much more so, to my eye at
least, than many flowers which are supposed to stake their lives on
attraction by being conspicuous. Hermann Müller has observed on this
same fact, and considers it to be clear that the display of colour can
be of no use to the plant, and must therefore be regarded as "a merely
accidental phenomenon,"[21]--_i.e._, a phenomenon not accounted for by
utility.
The crimson flowers of the larch, again, are certainly very
conspicuous as well as beautiful on the yet leafless boughs; and yet
they owe nothing to insects.
One other remark must be made on this passage from Mr. Darwin which
has formed my text. It does not pretend to account for the production
of beauty or even of conspicuousness. It only seeks to account for the
accumulation of that quality in certain plants, and its comparative
absence in others. The tendency in Nature to produce beauty is a
postulate in Mr. Darwin's theory.
The beauty of mountain blossoms has been referred to as supporting
the utility of beauty: it is not perfectly clear that even this can be
accounted for merely by the need of attracting insects. It is said by
the American writer to whom I have already referred, Mr. Meehan, that
the flowers of the Rocky Mountains are beautifully coloured, produce
as much seed as similar ones elsewhere, and yet that there is a
remarkable scarcity of insect life--so great, I understand him to
mean, as to render it highly improbable that the races of the flowers
can be perpetuated by insect agency.
We have hitherto, according to promise, been considering the beauty of
flowers as detached from all surrounding facts, and isolated from
all other parts of the plant. But, in fact, this beauty of the
inflorescence of plants is only one phenomenon of a much larger class.
The petals and sepals are only leaves; and it is difficult to argue
about the character of the flower-leaves and omit from thought the
stalk and root-leaves; and these leaves continually possess a wealth
of beauty both of form and colour for which no intelligible utility
has ever been suggested. The use made of conspicuous leaves in the
modern style of bedding-out and the cultivation in hot-houses of what
are called foliage plants, will recall this to every one. In many
cases the stems of plants, often the veins of the leaves, and often
the backs of the leaves, are the homes of distinct and beautiful
colouring, for which, so far as I know, no account can be given on
the score of use. To enlarge our view yet a little more, the brilliant
colours of the fungi and of the lichens, mosses, and sea-weeds, and,
lastly, the outburst of varied colours in the autumn--the crimson of
the bramble, the browns of the oaks, the red of the maple, the gold
of the elm, "the sunshine of the withering fern"--all these present
themselves to us as so closely akin to the painted beauty of flowers
that we cannot think of the one without the other; and we may well
hesitate to accept as satisfactory a theory which can offer no
explanation of phenomena so closely akin to those of flowers, except,
forsooth, that they are merely accidental. Once again, to widen the
range of our mental vision, the beauty of the vegetable world is but a
part of that great and complex mass of beauty from which we agreed
to segregate it; and viewed as part of that, it must have the same
explanation applied to it as the other beautiful phenomena of the
world.
It is worth while to remember that Beauty is no outcome of a long
period of evolution; it is no late event in the geologic history of
the world. The lowest forms of organic life no less than the highest
are clad in beauty. Many beings that are "simple structureless
protoplasm"--to use the language of Professor Allman as President of
the British Association this year--"fashion for themselves an
outer membraneous or calcareous case, often of symmetrical form
and elaborate ornamentation, or construct a silicious skeleton of
radiating spicula or crystal-clear concentric spheres of exquisite
symmetry and beauty."[22]
So, too, in the Silurian period, the corals and other marine
structures were, no doubt, endowed with every grace which could
please the eye of man, if he had been there. Beauty is the invariable
companion of Nature. It is difficult, therefore, to account for it
as a result of evolution; and, as for the theory that it was made
for man's delectation only, a single diatom or a single fossil from a
Silurian bed is enough to put the whole vain egotism to flight.
What are the results fairly deducible from these observations? They
seem to be the following:--
1. That conspicuousness is _a_ step towards fertilization in one
mode, and might, therefore, well be used by an artist loving at
once beauty and fertility.
2. That there is no such preponderating advantage in beauty as
should convert the ugly anemophilous flowers into the brilliant
entomophilous flowers.
3. That in an infinite number of cases beauty exists, but without
any relation to the mode of fertilization.
4. That it is maintained in many cases where the uglier and less
beautiful plant is more useful, as in the case of the violet.
5. That even where conspicuousness is useful, it furnishes no
complete account of the whole beauty of the flower.
Let us apply these facts to the two rival theories. If, on the one
hand, nothing has become beautiful but through the utility of beauty,
beauty will be found where it is useful and nowhere else. But we have
found beauty without finding utility; so that theory, on our present
knowledge, is inadmissible.
If, on the other hand, there be an artificer in Nature who loves at
once utility and beauty, he may use the one sometimes as a mean to
the other, or he may use beauty without utility; and the presence of
beauty without utility is intelligible.