Until a few decades ago, it was the universal belief that flowers had
been specially created for man’s exclusive delight. This was such an
easy way, you know, to overcome the difficulty of explaining the immense
variety of forms and colours in the floral world; and it was, above all,
so flattering to man’s egregious vanity. But one fine morning in May a
German naturalist, Conrad Sprengel, published a remarkable book in which
he pointed out that flowers owe their peculiar shape, colour, and
fragrance to the visits of insects. Not that the insects visit the
flowers in order to shape and paint and perfume them. On the contrary,
they visit them for the unæsthetic purpose of eating their pollen and
their honey; while the flowers’ scent and colour exist solely for the
purpose of indicating to winged insects at a distance where they can
find a savoury lunch.
But why should flowers take such pains to attract insects by serving
them with a breakfast of honey, and by hanging out big petals to serve
as coloured and perfumed signal-flags? Nature is economical in the
expenditure of energy; and as the production of honey and large flowers
costs the plant some of its vital energies, we may be sure that this
expenditure secures the plant some superior advantage. Sprengel noticed
that the insects, while pillaging flowers of their honey, unwittingly
brushed off with their wings and feet some of the fertilising dust or
pollen, and carried it to the pistil or female part of a flower. But it
remained for Darwin to point out what advantage this transference of the
pollen secured to the flower. Darwin, says Sir John Lubbock, “was the
first clearly to perceive that the essential service which insects
perform to flowers consists not only in transferring the pollen from the
stamens to the pistil, but in transferring it from the stamens of one
flower to the pistil of another. Sprengel had indeed observed in more
than one instance that this was the case, but he did not altogether
appreciate the importance of the fact. Mr. Darwin however, has not only
made it clear from theoretical considerations, but has also proved it,
in a variety of cases, by actual experiment. More recently Fritz Müller
has even shown that in some cases pollen, if placed on the stigma of the
same flower, has no more effect than so much inorganic dust; while, and
this is perhaps even more extraordinary, in others, the pollen placed on
the stigma of the same flower acted on it like poison”—a curious analogy
to the current belief that close intermarriage is injurious to mankind.
What Darwin and others have proved by their experiments is that
cross-fertilised flowers are more vigorous than those fertilised with
their own pollen, and have a more healthy and numerous offspring. With
this fact before us we need only apply the usual evolutionary formula to
account for the beauty of flowers. It is well known that Nature rarely,
if ever, produces two leaves or plants that are exactly alike. There is
also a natural tendency in all parts of a plant except the leaves to
develop other colours besides green. Now any plant which, owing to
chemical causes, favourable position, etc., developed an unusually
brilliant colour, would be likely to attract the attention of a winged
insect in search of pollen-food. The insect, by alighting on a second
flower soon after, would fertilise it with the pollen of the first
flower that adhered to its limbs, thus securing to the plant the
advantages of cross-fertilisation. Thanks to the laws of heredity, this
advantage would be transmitted to the young plants, among which again
those most favoured would gain an advantage and a more numerous
offspring. And thus the gradual development not only of coloured petals,
but of scents and honey, can be accounted for.
What makes this argument irresistible is the additional fact, first
pointed out by Darwin, that plants which are not visited by insects, but
are fertilised by the agency of the wind, are neither adorned with
beautifully-coloured flowers, nor provided with honey or fragrance. And
another most important fact: Darwin found that flowers which depend on
the wind for their fertilisation follow the natural tendency of objects
to a symmetrical form; whereas the irregular flowers are always those
fertilised by insects or birds. This points to the conclusion that
insects and birds are responsible not only for the colours and fragrance
of flowers, but also for the shape of those that are most unique and
fantastic. And this _a priori_ inference is borne out by thousands of
curious and most fascinating observations described in the works of
Darwin, Lubbock, Müller, and many others. The briefest and clearest
presentation of the subject is in Lubbock’s _Flowers, Fruits, and
Leaves_, which no one interested in natural æsthetics should fail to
read. There is indeed no more interesting study in biology than the
mutual adaptation of flowers, bees, butterflies, humming-birds, etc.;
for just as these animals have modified the forms of flowers, so the
flowers have altered the shape of these animals.
Many of the changes in the shapes of flowers are made not only with a
view to facilitate the visits of winged insects, but also for keeping
out creeping intruders, such as ants, which are very fond of honey,
but which, as they do not fly, would not aid the cause of
cross-fertilisation. Of these contrivances, “the most frequent are the
interposition of _chevaux de frise_, which ants cannot penetrate,
glutinous surfaces which they cannot traverse, slippery slopes which
they cannot climb, or barriers which close the way.”
How obtuse are those who, with Ruskin and Emerson, accuse science of
destroying the poetry of nature! What poetry is there in the thought
that flowers were made for unæsthetic man, when not one man in a
thousand ever takes the trouble to examine one, while for every single
flower on which a human eye ever rests, a million are born to blush
unseen?
But if we abandon the narrow anthropocentric point of view, and admit
that insects too have a right to live, how the scope of Nature’s poetry
widens! How easy it then becomes to share not only Wordsworth’s belief
that “every flower enjoys the air it breathes,” but to endow it with a
thousand thoughts and emotions like our own—delight in a gaily-coloured
floral envelope; hope that yonder gaudy butterfly will be attracted by
it; anxiety lest that “horrid” ant may steal some of its honey;
determination to breathe the sweetest perfume on this darling honey bee,
so as to induce it to speedily call again.
Love dramas, too, tragic and comic, are enacted in this world of flowers
and insects. Thus the Arum plant resorts to the following stratagem to
secure a messenger of love for carrying its pollen to a distant female
flower:—
“The stigmas come to maturity first, and have lost the possibility of
fertilisation before the pollen is ripe. The pollen must therefore be
brought by insects, and this is effected by small flies, which enter the
leaf, either for the sake of honey or of shelter, and which, moreover,
when they have once entered the tube, are imprisoned by the fringe of
hairs. When the anthers ripen, the pollen falls on to the flies, which,
in their efforts to escape, get thoroughly dusted with it. Then the
fringe of hairs withers, and the flies, thus set free, soon come out,
and ere long carry the pollen to another plant” (Lubbock).
Then there are male flowers which go a-courting like any amorous swain
of a Sunday night. One of these belongs to the Valisneria plant,
concerning which the same writer observes that “the female flowers are
borne on long stalks, which reach to the surface of the water, on which
the flowers float. The male flowers, on the contrary, have short,
straight stalks, from which, when mature, the pollen detaches itself,
rises to the surface, and, floating freely on it, is wafted about, so
that it comes in contact with the female flowers.”
But alas for the poor flowers! Few of them are thus privileged to roam
about and seek their own bride. Most flowers have no more free choice in
the selection of their spouse than an Oriental or a French girl. There
is no previous acquaintance, no courtship before marriage, hence no
Romantic Love, even if the undifferentiated germs of nervous protoplasm
in the plant were capable of feeling such an emotion.
Poor flowers! Their honeymoon is without pleasure, unconscious. The wind
may woo, the butterfly caress them—but the wind has no thought of the
flower, and the insect’s attachment is mere “cupboard love.” The beauty
of one flower cannot exist for another which has no eyes to see it; its
honey and its fragrance are not for a floral lover’s delight, but for a
gastronomic insect’s epicurean use. No modest coyness, no harmless
flirtation, no gallant devotion and self-sacrifice, enter into the
flower’s sexual life; not even the bitter-sweet pangs of jealousy, for,
as Heine has ascertained, “the butterfly stops not to ask the flower,
‘Has any one kissed thee before?’ nor does the flower ask, ‘Hast thou
already flitted about another?’”
Thus “flower-love,” with all its poetic analogies, has none of the
elements of Romantic Love. Even attraction fails, for plants are
commonly sessile, and cannot go forth to seek a mate.
“I prayed the flowers,
Oh, tell me, what is love?
Only _a fragrant sigh_ was wafted
Thro’ the night.”—_German Song._
Two important lessons of this chapter should, however, be carefully
borne in mind; for though our search for Love has so far yielded only
negative results, some light has been thrown on the general laws of
Beauty in Nature. The lessons are:—
(1) That there is in flowers a natural tendency towards Symmetry of
Form, all normal irregularities being due to the agency of insects and
birds.
(2) That the superior Beauty of one flower over another is due to its
superior vitality or Health, which, again, is promoted by
cross-fertilisation or intermarriage—the choosing of a mate not in the
same but in another flower-bed.
Regarding the beauty of flowers a further detail may be added. Some of
the coloured lines on flowers are so placed as to guide the visiting
bees to the nectar or honey. More complicated colour-patterns probably
owe their existence to the advantage of having an easy means of
recognition at a distance. It is well known that bees on any single
expedition visit the flowers of one species only. Now it has been
experimentally proved by Lubbock that bees can distinguish different
colours; and, if we may judge by analogy with the human eye, they can
distinguish colours at a greater distance than forms. Hence the
advantage to each flower of having its own colours in its flag.