by Grant Allen
The visitors for which Dutch clover specially lays itself out are for the most part bees. It disdains small pilferers. Each blossom has a long tube enclosing its honey, and only insects with a correspondingly long proboscis can reach its deep store of delicious nectar. It thus saves itself from being rifled uselessly by small insect riff-raff, such as flies and midges, which might visit the flower, as we botanists call it, “illegitimately” — that is to say, might rob the honey without conveying the pollen from the pollen-bags of one head to the sensitive surface or stigma of the next. The parts of the flower, in fact, are specially arranged with a definite relation to the head and the honey-sucking tube of hive bees and wild bees, which cannot visit it without dusting themselves over with pollen on one blossom which they unconsciously rub off on the receptive surface of the next. In one word, Dutch clover encourages bees for its own purposes, because they are useful to it, while it places obstacles in the way of smaller and useless insects, by burying its honey in a deep tube.
The head of Dutch clover shown in No. 6 is one which has been caught just at the very first moment of flowering. The florets or blossoms which make up the head begin opening from without and below, inward and upward. Thus in this head the outer and lower florets have opened, while the inner and upper ones are still in the bud. When a bee visits such a head of clover, he comes to it first from another head of the same kind; for bees do not usually mix their liquors; on one round of visits they confine themselves, as a rule, to a single species of flower only, and they probably store the honey of each kind in separate cells, just as we ourselves in our wine-cellars keep one bin for champagne, another for claret, and a third for Burgundy. The bee thus begins with the outer flower of the head, which he fertilises with pollen from the last plant he visited; he then goes on to the second row, where he dusts himself over with pollen for another flower-head; and the buds in the centre he leaves severely unnoticed.
As soon as he flies away, a very curious thing begins to happen. The flowers which he has unconsciously fertilised close over their seed-vessel, and grow gradually brown or withered. At the same time, as you see in No. 7, they turn down out of the way of the bees by bending the separate little stalks on which they are raised in the head, and tucking themselves tight against the common flower stem. This they do partly in order not to confuse and worry their allies the bees, but partly also to avoid certain other dangers to which I will recur later. Plants often try in such ways to save bees or butterflies time and trouble, because the easier they make matters for the bee or butterfly, the more likely is he to visit and fertilise them. He is a useful customer whom they desire to conciliate. If a bee on his rounds finds that any particular species of plant gives him unnecessary trouble in getting at the honey, he is apt to neglect it and pass it by, in order to devote himself to other kinds which he sees are more business-like and obliging. The moment he comes to a head of Dutch clover, then he knows at once that he may safely ignore the dry brown flowers tucked away against the stem, because they are already fertilised and honeyless; he therefore directs all his attention to the mature and open flowers which are now producing honey and ready for fertilisation. These form practically, as you will see, at each moment the outer row of the flower-head, and are the ones which naturally first engage his notice as he alights on the cluster.
No. 8 shows us the same head in a little later stage of advancement. Here, almost all the flowers have now been fertilised, and they are therefore turning their brown and faded florets downward against the stem. Two among them, which the bee has only just left, are caught in the very act of bending down, so as to get out of the way of any further visitor. The flowers in the centre, which are still erect, were not yet opened when the last bee paid a passing call on the community. They have unfolded their petals since, and are now standing up awaiting their turn to be visited by their winged ally, relieved of their honey, and duly fertilised. It sometimes takes four or five days for a single head to pass through all its stages.
In No. 9 we have a truly pathetic picture of a solitary old maid, perked up desolate and alone in the midst of her happier sisters. She was an unopened bud when some passing honey-gatherer visited and set the seeds of her more fortunate relations. The flower on her left, to be sure, has only just turned; it was the last to receive attention from its winged allies. If you search a field of Dutch clover, you will find every here and there such a solitary old maid. But you must bear in mind that none of this is true of the common purple clover, nor yet of the brilliant crimson kind (known to our farmers as “carnation trifolium”), both of which are distinct species with totally different marriage customs. The ingenious habit of turning the fertilised flowers downward out of the way of the insects is confined to a few species of white, pink, and yellow clovers. It is a little dodge on which they happen to have hit, but which has never occurred to their larger and more conspicuous red and purple cousins. So if you try to follow out these hints in nature, you must be careful to hunt for white kinds only.
No. 10 shows us the last stage in the life-history of a head of Dutch clover. All the flowers have by this time been fertilised; and each flower alike is now pressed down against the stem in a crumpled, brown, and withered-looking mass. The mere casual observer would say, “This clover is dead.” But it is nothing of the kind: it is only shamming. The main object of the flowering and fertilisation, after all, is the production of seed; just as among birds the main object of pairing and nesting is the laying of eggs and the hatching of their little ones. And this introduces us to a second consideration of great importance. Plants take care of their young. The seeds of clover are small, but they are rich in foodstuffs laid by for the use of the little plant at its start in life. Now, the parent flower is well aware that many insects love to lay their eggs and hatch out their grubs in pods of this character; if you have ever shelled peas, you must have seen such grubs very frequently in the pea-pods. The maternal instinct of the mother makes her lay her eggs where food is abundant; the maternal instinct of the mother-plant makes it do its best to protect its young against such devouring enemies.
In No. 11 we see a flower of Dutch clover cut open lengthwise, so as to show the little pod within, very much magnified, and with one valve opened. Tiny as these pods are, they usually contain two, three, or four seeds. Every kind of clover, owing to the richness of these seeds, is much exposed to the attacks of insect enemies. To baffle these wary foes the clovers have invented an extraordinary variety of protective devices, two of which I mean to examine in this essay. Dutch clover meets the difficulty by tucking down the flowers after fertilisation out of the way of the bee, and then retaining the withered corolla or set of petals which completely enclose and hide the pod in the centre. Indeed, such a head as you see in No. 10, all composed of brown and withered flowers, looks externally as if it were quite dead; but if you remove or cut open the sere and papery outer parts of the flower, you will find within them a vigorous little green pod, in which the miniature peas, after fertilisation, are maturing actively. In fact, the plant is only pretending to be dead; yet so effective is the pretence, and so well does the papery covering guard each pod against the egg-laying insects, that I cannot remember ever to have found a single grub in the seeds of clover. This may seem to you a small matter to guard against; but if you open the seed-capsules of the common little mouse-ear chickweed, which has no such protection, you will find in almost every capsule a small red grub busily employed in eating the seeds which the plant had laid by for the continuance of its species. It is thus a distinct advantage to the clovers in the struggle for life that they have invented devices which enable them to guard their embryo young from the assaults of insects.
Every species of clover — and there are many — has some dodge of its own for thus protecting its growing pods and seeds from the grubs which would destroy them. I only propose, however, to examine in detail here one more of these dodges. We have another kind of clover, a good deal like Dutch clover at a casual glance
, and commonly confounded with it by unobservant people, though, as we shall soon see, the habits and manners of the two kinds are in reality very different. The strawberry clover, as it is called, is a somewhat lower and smaller species than Dutch clover, which it resembles in its creeping stems and in its rich foliage. But the flowers are not separately stalked in the head, so that they cannot turn down after fertilisation like those we have just been considering. Moreover, the stems and flower-heads are much hairier; and this difference is due to the two facts that the strawberry clover is smaller, and has a shorter tube than its Dutch relation. It would thus be easy for ants and other crawling insects to creep up the stem and steal the honey, which is intended for the use of fertilising visitors. To prevent this misfortune, and to keep its nectar for the regular customers, the strawberry clover produces a number of hairs on the stem, which baffle the ants, to whom such hairs are an impenetrable thicket. But you may ask, “Why are not ants just as good as bees for the clover?” For this reason: flying insects are mainly guided by sight and colour; they flit straight from one flower to another of the same species; and their heads are exactly adapted to the shape of the flowers, which in turn have modelled their tubes and organs on purpose to fit them. Ants and creeping insects, on the contrary, are attracted merely by the sense of smell: they notice scent of honey; they climb up all stems indiscriminately in search of it; they are bare-faced thieves with no organs adapted for carrying pollen; and as they go about in the most reckless fashion from one kind of plant to another, if they did ever by chance succeed in fertilising a casual flower, they would produce, not true species, but monstrous and meaningless hybrids. Therefore, many plants protect themselves by endless devices against the crawling ants, just as obviously as they endeavour to allure the winged bees, beetles, and butterflies. I may add that the head of strawberry clover is further protected against climbing insects by a number of lobed bracts at its base, which effectually disperse these thieving marauders.
While the strawberry clover is young and but recently opened, you might easily mistake it for a small and pinky specimen of Dutch clover. If you look closer, however, you will see that the petals are not so large, the tube not so deep, and the calyx much hairier. Nevertheless, as you may observe in No. 12, the hairs do not seriously get in the way of the bee during the stage when the flowers are just fit for fertilisation. As soon as the bee has left the plant, however, something happens which is quite different to the turning down of the florets in Dutch clover. The calyx or little cup which encloses each separate flower begins to swell and inflate itself like a balloon or bladder. In No. 13 you can see the beginnings of this curious process; each calyx is slightly swelling round the tiny pod which it encloses. In Dutch clover, the pod is longer than the calyx, and the plant trusts for protection to the papery petals or corolla. But in strawberry clover, the calyx, after flowering, becomes very much inflated, thin, and netted; and in this state it completely encloses the growing pod. No. 14 illustrates an intermediate stage in the process, with a solitary old maid still unfertilised, and the other flowers larger and more inflated. In No. 15 the inflation is complete: each little calyx has now swelled out into a small balloon, enclosing its pod. The whole flower-head then becomes very compact, and assumes a pink tint, so that it somewhat resembles a strawberry, whence its ordinary name, though, as a matter of fact, it is much more like a raspberry. You will observe that the beautiful network on the bladder-like head is closely covered with numerous hairs, which further help to protect the pods from the attacks of insects.
The truth is, Dutch clover is a denizen of rich and lush meadows, where it can take care of itself, and for which alone it is perfectly adapted. Strawberry clover, on the other hand, has chosen its home in close-cropped pastures, where its creeping habit and low stature help to save it from destruction. The dry and hairy heads are not relished by sheep, and you will often see them left uncropped where the neighbouring foliage has been closely nibbled. The swollen calyx with its hairs also keeps off egg-laying enemies. In No. 16 we have an illustration of one such fruiting flower, cut open lengthwise, so as to show the way the bladder-like calyx grows out around the pod as it ripens.
Now, what is oddest of all, every one of twenty or twenty-five species of clover has some dodge of its own for protecting its seeds after fertilisation. This shows how much these rich grains are sought after, and how carefully the plant is compelled to guard them. In some kinds, the calyx is a loose fluff of silky hair, enclosing the pod; in others, it is hard like a nut, or has stiff and pointed lobes which are sharp and prickly. One species closes its hardened lips over the growing seeds and pretends to be empty; a second develops a starry, thistle-like head, with tufts of thick hair, which conceal the swelling pod from observation. But the subterranean clover has hit upon a still stranger and more ingenious device. It is a little creeping annual, much addicted to dry pastures or close-cropped hillsides, and particularly common on low knolls or barrows, nibbled over by numerous sheep and donkeys. Under these circumstances, it has a hard fight to protect its nutritious seeds and seedlings. It has taken, therefore, to producing small heads of loose white flowers, which look at first sight like poor specimens of Dutch clover. But if you gaze closer you will see that each tiny head consists of two or three properly developed flowers, with four or five undeveloped or abortive blossoms in the centre of the group. These undeveloped blossoms form a sort of living corkscrew. After fertilisation, the stems bend down towards the ground; the corkscrew-like abortive flowers worm their way by pushing into the soil; the pods are pressed down or buried in the loose mould; and the plant thus sows its own seed for itself quite as effectually as a gardener could sow it. This is, perhaps, the furthest point which maternal solicitude has ever reached in the vegetable kingdom.
I hope technical botanists will forgive me some slight but unimportant simplifications in this not entirely accurate mode of presentation.
VI. THOSE HORRID EARWIGS
THIS is an age of vindications. Robespierre has been vindicated, and so has Marat; officious apologists have attempted to whitewash the unamiable character of Richard III.; Tiberius has been described as “a wise and great ruler”; and even poor Caligula has been lamely excused, on the ground of insanity, for such playful little freaks as making his favourite saddle-horse a Roman consul. Nobody’s reputation is safe nowadays from the vindicator. It is the same in the animal world. New light is constantly being cast on the idiosyncrasies of the rattlesnake; we are assured from day to day that the cobra, though slightly venomous, is an excellent wife and a devoted mother; the scorpion only stings when you put him on the defensive or when he runs for his life; and the tarantula, we are told, has been most unjustifiably and cruelly blown upon. Has not the poet of “The Bad Boy’s Book of Beasts” informed us that —
“The tiger, on the other hand, is kittenish and mild;
He makes a pretty plaything for any little child;
And mothers of large families (who claim to common sense)
Will find a tiger well repay the trouble and expense.”
In the midst of all these vindications, shall the harmless, unnecessary earwig go unvindicated from the aspersions that too often assail his character? A thousand times, no! Because he is small, he shall not be insulted with impunity. I see a helpless animal unduly exposed to vile detractions, and openly pursued with undeserved asperity. The sight arouses all the latent chivalry of my nature. I will gird on my sword to do battle for the right, and rush in, a scientific St. George, in defence of the innocent but persecuted earwig.
That my hero (or heroine) has a bad name in the world I am not careful to deny. Calumny has dogged it from its earliest days. Its very name enshrines a myth which is in itself a libel. It is called earwig, gossips will tell you, because it creeps into the ears of incautious sleepers in the open air, and so worms its way to the brain, where, if you will believe the purveyors of folk-lore natural history, it grows to a gigantic size, “as big as a goose’s egg,” an
d finally kills its unhappy victim. It is true, science knows nothing of this form of brain-disease; it has tried the case before an impartial tribunal, and the earwig has left the court without a stain on its character. Some etymologists have even endeavoured to persuade us that the name earwig itself is but a corruption of ear-wing, a word which they suppose to be derived from the shape of its flying organs. There, however, our philologists are surely crediting the people with more knowledge than they possess; very few gardeners or countrymen are aware that earwigs have wings, while the general public never sees them flying. Besides, the German name Ohrwurm, or “ear-worm,” and the French Perce-oreille, or “pierce-ear,” suffice to show that the myth is not confined to our own country. All over the world this harmless and on the whole beneficent creature (for he is a good scavenger) is regarded with superstitious fear and aversion; all over the world he is ruthlessly destroyed whenever found; and modern science alone is the first to attempt the herculean task of rehabilitating him.
Before you begin to rehabilitate anybody, however, it is first desirable to know something about himself, his family, and his antecedents. I will therefore set out with a brief description of the earwig and his relations. Almost everybody knows well that earwigs are black little creeping insects, which frequent dark spots, avoid the light, and love to take refuge under stones or woodwork. The earwig, in point of fact, is a nocturnal animal. Like the bat and the owl, he hides during the daytime, and only prowls forth at night in search of food and adventures. Plain as he is to outward view, his diet might suit the daintiest of poets, for he lives for the most part on the petals of flowers, on which account he is hated with a deadly hatred by gardeners. But the diet of the race is not wholly floral. Earwigs prefer petals and other soft parts of plants; but they will put up with leaves or growing shoots, and even feed to a small extent on dead or decaying animal matter. That they are fond of fruit you must have observed for yourself in the case of peaches and strawberries; though I fancy they never attack a perfect specimen for themselves. My own experience is that they wait till a wasp has bored a hole in the rind of an apricot or a nectarine, and then creep in to enlarge it by their additional efforts. If on any such occasion, instead of throwing the fruit away in disgust, you will watch the robbers with a pocket lens, you may (if fortunate) have a chance of observing the mode of action of the mouth organs. That is the difference between the point of view of the naturalist and the general public. The outsider says: “What a nuisance! This peach is full of earwigs!” The naturalist says: “How lucky! Now I shall have a chance of seeing how he uses his mandibles!”
