Читать книгу Flowers and Their Pedigrees - Allen Grant - Страница 8

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Fig. 1.—The Common Daisy.

Have you ever paused for a moment to consider how much man loses for want of that microscopic eye upon whose absence complacent little Mr. Pope, after his optimistic fashion, was apparently inclined rather to congratulate his fellow-beings than otherwise? What a wonderful world we should all live in if only we could see it as this little beetle here sees it, half buried as he is in a mighty forest of luxuriant tall green moss! Just fancy how grand and straight and majestic those slender sprays must look to him, with their waving, feathery branches spreading on every side, a thousand times more gracefully than the long boughs of the loveliest tropical palm trees on some wild Jamaican hill-side. How quaint the tall capsules must appear in his eyes—great yellow seed-vessels nearly as big as himself, with a conical, pink-edged hood, which pops off suddenly with a bang, and showers down monstrous nuts upon his head when he passes beneath. Gaze closely into the moss forest, as it grows here beside this smooth round stone where we are sitting, and imagine you can view it as the beetle views it. Put yourself in his place, and look up at it towering three hundred feet above your head, while you vainly strive to find your way among its matted underbrush and dense labyrinths of close-grown trunks. Then just look at the mighty monsters that people it. The little red spider, magnified to the size of a sheep, must be a gorgeous and strange-looking creature indeed, with his vivid crimson body and his mailed and jointed legs. Yonder neighbour beetle, regarded as an elephant, would seem a terrible wild beast in all seriousness, with his solid coat of bronze-burnished armour, his huge hook-ringed antennæ, and his fearful branched horn, ten times more terrible than that of a furious rhinoceros charging madly through the African jungle. Why, if you will only throw yourself honestly into the situation, and realise that awful life-and-death struggle now going on between an ant and a May-fly before our very eyes, you will see that Livingstone, and Serpa Pinto, and Gordon Cumming are simply nowhere beside you: that even Jules Verne’s wildest story is comparatively tame and commonplace in the light of that marvellous miniature forest. Such a jumble of puzzle-monkeys, and bamboos, and palms, and banyan trees, and crags, and roots, and rivers, and precipices was never seen; inhabited by such a terrible and beautiful phantasmagoria of dragons, hippogriffs, unicorns, rocs, chimæras, serpents, and wyverns as no mediæval fancy ever invented, no Greek mythologist ever dreamt of, and no Arabian story-teller ever fabled. And yet, after all, to our clumsy big eyes, it is but a little patch of familiar English grass and mosses, crawled over by half a dozen sleepy slugs and long-legged spiders, and slimy earthworms.

Still, if you so throw yourself into the scene, you cannot avoid carrying your own individuality with you into the beetle’s body. You fancy him admiring that fairy landscape as you would admire it were you in his place, provided always you felt yourself quite secure from the murderous jaws and hooked feet of some gigantic insect tiger lurking in the bristly thicket behind your back. But, as a matter of fact, I greatly doubt whether the beetle has much feeling for beauty of scenery. For a good many years past I have devoted a fair share of my time to studying, from such meagre hints as we possess, the psychology of insects: and on the whole I am inclined to think that, though their æsthetic tastes are comparatively high and well-developed, they are, as a rule, decidedly restricted in range. Beetles and butterflies only seem to admire two classes of visible objects—their own mates, and the flowers in which they find their food. They never show much sign of deliberate love for scenery generally or beautiful things in the abstract outside the limits of their own practical life. If this seems a narrow æsthetic platform for an intelligent butterfly, one must remember that our own country bumpkin has perhaps a still narrower one; for the only matter in which he seems to indulge in any distinct æsthetic preference, to exercise any active taste for beauty, is in the choice of his sweetheart, and even there he is not always conspicuous for the refinement of his judgment. But there is a way in which one can really to some extent throw oneself into the mental attitude of a human being reduced in size so as to look at the moss-forest with the eye of a beetle, while retaining all the distinctive psychological traits of his advanced humanity: and that is by making himself a microscopic eye with the aid of a little pocket-lens. Even for those who do not want to use one scientifically, it opens a whole universe of new and delightful scenery in every tuft of grass and every tussock of wayside weeds; and by its aid I hope to show you this morning how far the eyes and æsthetic tastes of insects help us to account for the pedigree of our familiar childish friend, the daisy. No fairy tale was ever more marvellous, and yet certainly no fairy tale was ever half so true.

I propose then, to-day, to dissect one of these daisies with my little knife and glass, and unravel, if I can, the tangled skein of causes which have given it its present shape, and size, and colour, and arrangement. If you choose, you can each pick a daisy for yourselves, and pull it to pieces as I go along, to check off what I tell you; but if you are too lazy, or can’t find one within reach, it doesn’t much matter; for you can at least carry the picture of so common a flower well enough in your mind’s eye to follow what I have to say without one: and that is all that is at all necessary for my present purpose.

The question as to how the daisy came to be what it is, is comparatively a new one. Until a short time ago everybody took it for granted that daisies had always been daisies, cowslips always cowslips, and primroses always primroses. But those new and truer views of nature which we owe to Mr. Darwin and Mr. Herbert Spencer have lately taught us that every plant and every animal has a long history of its own, and that this history leads us on through a wonderful series of continuous metamorphoses compared with which Daphne’s or Arethusa’s were mere single episodes. The new biology shows us that every living thing has been slowly moulded into its existing shape by surrounding circumstances, and that it bears upon its very face a thousand traces of its earlier stages. It thus invests the veriest weed or the tiniest insect with a fresh and endless interest: it elevates them at once into complex puzzles for our ingenuity—problems quite as amusing and ten times as instructive as those for whose solution the weekly papers offer such attractive and unattainable prizes. What is the meaning of this little spur? How did it get that queer little point? Why has it developed those fluffy little hairs? These are the questions which now crop up about every part of its form or structure. And just as surely as in surveying England we can set down Stonehenge and Avebury to its prehistoric inhabitants, Watling Street and the Roman Wall to its southern conquerors, Salisbury and Warwick to mediæval priests and soldiers, Liverpool and Manchester to modern coal and cotton—just so surely in surveying a flower or an insect can we set down each particular point to some special epoch in its ancestral development. This new view of nature invests every part of it with a charm and hidden meaning which very few among us have ever suspected before.

Pull your daisy to pieces carefully, and you will see that, instead of being a single flower, as we generally suppose at a rough glance, it is in reality a whole head of closely packed and very tiny flowers seated together upon a soft fleshy disk. Of these there are two kinds. The outer florets consist each of a single, long, white, pink-tipped ray, looking very much like a solitary petal: the inner ones consist each of a small, golden, bell-shaped blossom, with stamens and pistil in the centre, surrounded by a yellow corolla much like that of a Canterbury bell in shape, though differing greatly from it in size and colour. The daisy, in fact, is one of the great family of Composites, all of which have their flowers clustered into similar dense heads simulating a single blossom, and of which the sunflower forms perhaps the best example, because its florets are quite large enough to be separately observed even by the most careless eye.

Fig. 2.—Ray floret of Daisy.

Fig. 3.—Central floret of Daisy.

Now, if you look closely at one of the central yellow florets in the daisy, you will see that its edge is vandyked into four or five separate pointed teeth exactly like those of the Canterbury bell. These teeth clearly point back to a time when the ancestors of the daisy had five separate petals on each flower, as a dog-rose or a May-blossom still has. Again, before the flowers of the daisy had these five separate petals, they must have passed through a still earlier stage when they had no coloured petals at all. And as it is always simpler and easier to recount history in its natural order, from the first stages to the last, rather than to trace it backward from the last to the first, I shall make no apology for beginning the history of the daisy at the beginning, and pointing out as we go along the marks which each stage has left upon its present shape or its existing arrangement and colour.

Fig. 4.—Longitudinal section of Common Buttercup.

The very earliest ancestor of the daisy, then, with which we need deal to-day, was an extremely simple and ancient flower, hardly recognisable as such to any save a botanical eye. And here I must begin, I fear, with a single paragraph of rather dull and technical matter, lest you should miss the meaning of some things I shall have to tell you in the sequel. If you look into the middle of a buttercup or a lily you know that you will see certain little yellow spikes and knobs within the petals, which form a sort of central rosette, and look as if they were put there merely to give finish and completeness to the whole blossom. But in reality these seemingly unimportant spikes and knobs are the most important parts, and the only indispensable parts, of the entire flower. The bright petals, which alone are what we generally have in our minds when we think of flowers, are comparatively useless and inessential organs: a vast number of flowers have not got them at all, and, in those which have got them, their purpose is merely subsidiary and supplementary to that of the little central spikes and knobs. For the small yellow rosette consists of the stamens and pistils—the ‘essential floral organs,’ as botanists call them. A flower may be complete with only a single stamen or a single pistil, apart from any petals or other bright and conspicuous surroundings; and some of the simplest flowers do actually consist of such separate parts alone: but without stamens and pistils there can be no flower at all. The object of the flower, indeed, is to produce fruit and seed, and the pistil is the seed-vessel in its earliest form; while the stamen manufactures the pollen without which the seeds cannot possibly be matured within the capsules. In some species the stamens and pistils occur in separate flowers, or even on separate plants; in others, the stamens and pistils occur on the same plant or in the same flower, and this last is the case in almost all the blossoms with which we are most familiar. But the fundamental fact to bear in mind is this—that the stamens and pistils are the real and essential parts of the flower, and that all the rest is leather and prunella—mere outer decoration of these invariable and necessary organs. The petals and other coloured adjuncts are, as I hope to show you, nothing more than the ornamental clothing of the true floral parts; the stamens and pistils are the living things which they clothe and adorn. Now probably you know all this already, exactly as the readers of the weekly reviews know by this time all about the personage whom we must not describe as Charlemagne, or the beings whom it is a mortal sin to designate as Anglo-Saxons. But then, just as there are possibly people in the worst part of the East End who still go hopelessly wrong about Karl and the Holy Roman Empire, and just as there are possibly people in remote country parishes who are still the miserable victims of the great Anglo-Saxon heresy, so, doubtless, there may yet be persons—say in the western parts of Cornwall or the Isle of Skye—who do not know the real nature of flowers; and these persons must not be wholly contemned because they happen not to be so wise as we ourselves and the Saturday Review. An eminent statistician calculates that Mr. Freeman has demolished the truculent Anglo-Saxon in 970 several passages, and yet there are even now persons who go on firmly believing in that mythical being’s historical existence. And the moral of that is this, as the Duchess would say, that you should never blame any one for telling you something that you knew before; for it is better that ninety-nine wise men should be bored with a twice-told tale, than that one innocent person should be left in mortal error for lack of a short and not wholly unnecessary elementary explanation.

Fig. 5.—Frond and flower of Duckweed.

The simplest and earliest blossoms, then—to return from this didactic digression—were very small and inconspicuous flowers, consisting, probably, of a single stamen and a single pistil each. Of these simplest and earliest forms a few still luckily survive at the present day; for it is one of the rare happy chances in this queerly ordered universe of ours that evolution has almost always left all its footmarks behind it, visibly imprinted upon the earth through all its ages. When any one form develops slowly into another, it does not generally happen that the parent form dies out altogether: on the contrary, it usually lingers on somewhere, in some obscure and unnoticed corner, till science at last comes upon it unawares, and fits it into its proper place in the scale of development. We have still several fish in the very act of changing into amphibians left in a few muddy tropical streams; and several oviparous creatures in the very act of changing into mammals left in the isolated continent of Australia; and so we have also many low, primitive, or simple forms of plants and animals left in many stray situations in every country. Amongst them are some of these earliest ancestral flowers. On almost every wayside pond you will find all the year round a green film of slimy duckweed. This duckweed is, as it were, the Platonic idea of a flowering plant—the generic type common to them all reduced to its simplest elements. It has no roots, no stem, no branches, no visible blossom, no apparent seed; it consists merely of solitary, roundish, floating leaves, budding out at the edge into other leaves, and so spreading till it covers the whole pond. But if you look closely into the slimy mass in summer time, you may be lucky enough to catch the weed in flower—though not unless you have a quick eye and a good pocket-lens. The flowers consist of one, and sometimes two, stamens and a pistil, growing naked out of the edge of the leaf. No one but a botanist could ever recognise their nature at all, for they all look like mere yellowish specks on the slender side of the green frond; but the pistil contains true seeds, and the stamens produce true pollen, and from the botanical standpoint that settles the question of their floral nature at once. They are, in fact, representatives of the simplest original form of flower, preserved to our own day on small stagnant ponds, where the competition of other plants does not press them hard as it has pressed their congeners on dry land or in open lakes and rivers.[1] From some such simple form as this we may be pretty sure that all existing flowering plants are ultimately descended.

a, Carpels or ovaries; b, stamens; c, petals; d, calyx.

Fig. 6.—Diagram of primitive dicotyledonous flower.

In most modern flowers, however, each blossom contains several stamens and several carpels (or pistil-divisions), and the way in which such a change as this might come about can be easily imagined; for even in many existing plants, where the separate flowers have only a single stamen or a single pistil each, they are nevertheless so closely packed together that they almost form a single compound flower, as in the case of the bur-reed and the various catkins, not to mention the arum and the spurge, where only a trained eye can make out the organic separateness. I shall not trouble you much, however, with these earlier stages in the development of the daisy, both because I shall describe them elsewhere in part, à propos of other subjects, and because the later stages are at once more interesting and more really instructive. It must suffice to say that at some very ancient period the ancestors of the daisy, and of one half the other modern flowers, had acquired an arrangement of stamens and pistils in groups of five, so that each compound flower had as a rule a pistil of five or ten carpels, surrounded by a row of five or ten stamens. And almost all their existing descendants still bear obvious traces of this original arrangement in rows of fives. On the other hand, the ancestors of our lilies, and of the other half of our modern flowers, had about the same period acquired an arrangement in rows of three. And of this other ternary arrangement all their existing descendants still bear similar traces. In fact, most flowers at the present day show clear signs of being derived either from the original five-stamened or the original three-stamened blossom. I don’t mean to say that this is the only mark of distinction between the two great groups: on the contrary, it is only a very minor one; but it is for our present purpose the one of capital importance.

a, Carpels or ovaries; b, stamens, inner row; c, stamens, outer row; d, petals; e, calyx.

Fig. 7.—Diagram of primitive monocotyledonous flower.

The very primitive five-parted common ancestor of the daisy, the rose, the buttercup, and our other quinary flowers, was still an extremely simple and inconspicuous blossom. It had merely green leaves and plain flower-stems, surmounted by a row of five or ten stamens, inclosing five or ten carpels. Perhaps beneath them there may have been a little row of cup-shaped green bracts, the predecessors of the calyx which supports all modern flowers; but of this we cannot be at all sure. At any rate, it had no bright-coloured petals. The origin of these petals is due to the eyes and selective tastes of insects; and we must look aside for a moment at the way in which they have been produced, in order rightly to understand the ancestry of the daisy.

No pistil ever grows into a perfect fruit or sets ripe and good seeds until it is fertilised by a grain of pollen from a stamen of its own kind. In some plants the pollen is simply allowed to fall from the stamens on to the pistil of the same flower; but plants thus self-fertilised are not so strong or so hearty as those which are cross-fertilised by the pollen of another. The first system resembles in its bad effect the habit of ‘breeding in and in’ among animals, or of too close intermarriages among human beings; while the second system produces the same beneficial results as those of cross-breeding, or the introduction of ‘fresh blood’ in the animate world. Hence, any early plants which happened to be so constituted as to allow of easy cross-fertilisation would be certain to secure stronger and better seedlings than their self-fertilised neighbours; and wherever any peculiar form or habit has tended to encourage this mode of setting seeds, the plants have always prospered and thriven exceedingly in the struggle for existence with their less fortunate congeners. A large number of flowers have thus become specially adapted for fertilisation by the wind, as we see in the case of catkins and grasses, where the stamens hang out in long pendulous clusters, and the pollen is easily wafted by the breeze from their waving filaments to the pistils of surrounding flowers. In such cases as these, the stamens are generally very long and mobile, so that the slightest breath shakes them readily; while the sensitive surface of the pistil is branched and feathery, so as readily to catch any stray passing grain of wind-borne pollen.

But there are other flowers which have adopted a different method of getting the pollen conveyed from one blossom to another, and this is upon the heads and legs of honey-eating insects. From the very first, insects must have been fond of visiting flowers for the sake of the pollen, which they used to eat up without performing any service to the plant in return, as they still feloniously do in the case of several wind-fertilised species; and to counteract this bad habit on the part of their unbidden guests, the flowers seem to have developed a little store of honey (which the insects prefer to pollen), and thus to have turned their visitors from plundering enemies into useful allies and friends. For even the early pollen-eaters must often unintentionally have benefited the plant, by carrying pollen on their heads and legs from one flower to another; but when once the plant took to producing honey, the insects largely gave up their habit of plundering the pollen, and went from blossom to blossom in search of the sweet nectar instead. As they did so, they brushed the grains of pollen from the stamens of one blossom against the pistil of the next, and so enabled the flowers to set their seed more economically than before.

Simultaneously with this change from fertilisation by the wind to fertilisation by insects, there came in another improvement in the mechanism of flowers. Probably the primitive blossom consisted only of stamens and pistil, with, at best, a single little scale or leaf as a protection to each. But some of the five-rowed flowers now began to change the five stamens of the outer row into petals; that is to say, to produce broad, bright-coloured, and papery flower-rays in the place of these external stamens. The reason why they did so was to attract the insects by their brilliant hues; or, to put it more correctly, those flowers which happened to display brilliant hues as a matter of fact attracted the insects best, and so got fertilised oftener than their neighbours. This tendency on the part of stamens to grow into petals is always very marked, and by taking advantage of it gardeners are enabled to produce what we call double flowers; that is to say, flowers in which all the stamens have been thus broadened and flattened into ornamental rays. Even amongst wild flowers, the white water-lily shows us every gradation between fertile pollen-bearing true stamens and barren broad-bladed petals. To put it shortly and dogmatically, petals are in every case merely specialised stamens, which have given up their original function of forming pollen, in order to adopt the function of attracting insects.

Fig. 8.—Transition from stamen to petal in White Water-lily.

The five-rowed ancestors of the daisy found a decided advantage in thus setting apart one outer row of stamens as coloured advertisements to lure the insects to the honey, while they left the inner rows to do all the real work of pollen-making. They very rapidly spread over the world, and assumed very various forms in various places. But wherever they went, they always preserved more or less trace of their quinary arrangement; and to this day, if you pick almost any flower belonging to the same great division of dicotyledons (the name is quite unimportant), you will find that it has at least some trace of its original arrangement in rows of five. The common stonecrop and its allies keep up the arrangement best of any; for they have each, as a rule, five petals; each petal has its separate bract, making a calyx or flower-cup of five pieces or sepals; inside are one or two rows of five stamens each; and in the centre, a pistil of five carpels. Such complete and original symmetry as this is not now common; but almost all the five-rowed flowers retain the same general character in a somewhat less degree. The buttercup, for example, has one outer row of five sepals, then five petals, and then several crowded rows of stamens and carpels. And in the petals at least the harmony is generally complete. There are five in the dog-rose, in the violet, in the pea-blossom, in the pink, in the geranium, and (speaking generally) in almost every plant that grows in our gardens, our fields, or our woodlands, unless it belongs to the other great division of trinary flowers, with all their organs in groups of three. And now, if you will pull open one of the inner yellow florets of your daisy, you will see that it has five stamens and five little lobes to the bell-shaped corolla, to show its ancestry plainly on its face, and ‘to witness if I lie.’

Fig. 9.—Corolla of Primrose.

Fig. 10.—Corolla of Harebell.

But the original bright-coloured ancestor of the daisy must have had five separate petals, like the dog-rose or the apple-blossom at the present day. How then did these petals grow together into a single bell-shaped corolla, as we see them now in the finished daisy? Well, the stages and the reasons are not difficult to guess. As flowers and insects went on developing side by side, certain flowers learnt to adapt themselves better and better to their special insects, while the insects in return learnt to adapt themselves better and better to their special flowers. As bees and butterflies got a longer proboscis with which to dive after honey into the recesses of the blossoms, the blossoms on their part got a deeper tube in which to hide their honey from all but the proper insects. Sometimes this is done, as in the larkspur, the violet, and the garden nasturtium, by putting the honey at the bottom of a long spur or blind sac; and if you bite off the end of the sac in the nasturtium you will find a very appreciable quantity of nectar stored up in it. But most highly specialised flowers have hit upon a simpler plan, which is to run all their petals together at the bottom into a tube, so long that no useless insect can rob the honey without fertilising the plant, and so arranged that the proboscis of the bee or butterfly can rub against the stamens and pistil on the way down. In pinks and their allies we see some rude approach to this mode of growth; for there each petal has a long claw (as it is called), bearing the expanded part at the end; and these claws when firmly pressed together by the calyx practically form a tube in five pieces: but in the perfectly tubular flowers, like the primrose, the arrangement is carried a great deal further; for there we have the claws all grown into a single piece, with the expanded petals forming a continuous fringe of five deeply cleft lobes, representing the five original and separate pieces of the pinks.[2] Now, in the primrose, again, we still find the five petals quite distinct at the edge, though their lower portion has grown together into a regular tube; but in the harebell or the Canterbury bell we see that the whole blossom has become bell-shaped, and that the five originally separate petals are only indicated by five slightly projecting points or lobes which give the tubular corolla its vandyked margin. And if you look at the little central florets of the daisy or the sunflower, you will observe that they too exactly resemble the Canterbury bell in this particular. Hence we can see that their ancestors, after passing through stages more or less analogous to those of the pinks and the primroses, at last reached a completely united and tubular or campanulate form, like that of the heath or the Canterbury bell.

Fig. 11.

Section of floret of Daisy.

There is one minor point, however, in the development of the daisy which I only notice because I am so afraid of that terrible person, the microscopic critic. This very learned and tedious being goes about the world proclaiming to everybody that you don’t know something because you don’t happen to mention it; and for fear of him one is often obliged to trouble one’s readers with petty matters of detail which really make no difference at all except to such Smelfunguses in person. Being themselves accustomed to weary us with the whole flood of their own unspeakable erudition, every time they open their mouths, they imagine that everybody else must be ignorant of anything which he doesn’t expressly state; as though you might never talk of a railway journey without giving at full the theory of kinetic energy as applied to the coal in the furnace. For their sake, then, I must add that, when the daisy’s ancestors had reached a level of development equivalent to that of the heath and the Canterbury bell, they differed in one respect from them just as the primrose still does. In the heath and the harebell, the stamens remain quite separate from the tube formed by the petals; but in the primrose and the daisy the stalks of the stamens (filaments, the technical botanists call them) have coalesced with the petals, so that the pollen seems to hang out in little bags from the walls of the tube itself. This is a further advance in the direction of specialised arrangements for insect-fertilisation; and it shows very simply the sort of cross-connections which we often get among plants or animals. For while the daisy is more like the Canterbury bell in the shape of its corolla, it is more like the primrose in the arrangement of its stamens. Or, to put it more plainly, while the Canterbury bell has hit upon one mode of adaptation in the form of its tube, and while the primrose has hit upon another mode in the insertion of its stamens, the daisy has hit upon both together, and has combined them in a single flower. And now, my dear Smelfungus, having given way to your prejudices upon this matter, allow me to assure you that nothing will induce me to enter into the further and wholly immaterial difference between hypogynous and epigynous corollas. For every one but you, the very names, I am sure, will be quite sufficient apology for my reticence. These, in fact, are subjects which, like the ‘old familiar Decline and Fall off the Rooshian Empire,’ had better be discussed ‘in the absence of Mrs. Boffin.’

When the ancestors of the daisy had reached the stage of united tubular blossoms, like the harebell, with stamens fastened to the inside wall of the tube, like the primrose, they must, on the whole, have resembled in shape the flowers of the common wild white comfrey, more nearly than any other familiar English plant. The next step was to crowd a lot of these bell-shaped blossoms together into a compact head. If you compare a cowslip with a primrose, you can easily understand how this is done. According to many of our modern botanists, cowslips and primroses are only slightly divergent varieties of a single species; and in any case they are very closely related to one another. But in the primrose the separate blossoms spring each on a long stalk of its own from near the root; while in the cowslip, the common stem from which they all spring is raised high above the ground, and the minor flower-stalks are much shortened. Thus, instead of a bunch of distinct flowers, you get a loose head of crowded flowers. Increase their number, shorten their stalks a little more, and pack them closely side by side, and you would have a compound or composite flower like the daisy. In fact, we often find in nature almost every intermediate stage: for instance, among the pea tribe we have all but solitary flowers in the peas and beans, long clusters in the laburnum and wistaria, and compact heads in the clovers. The daisies and other composites, it is true, carry this crowding of flowers somewhat further than almost any other plants; but still even here you can trace a gradual progress, some approach to their habit being made by allied families elsewhere; while some composites, on the other hand, have stopped short of the pitch of development attained by most of their race. Thus, certain campanulas have their flowers packed tightly together into a head, which looks at first sight a single blossom, just as deceptively as the daisy does; and a still nearer relative, the scabious, even more strikingly resembles the composite form. So that the daisies and their allies have really only carried out one step further a system of crowding which had been already begun by many other plants.

Fig. 12.—Section of head of Daisy.

If you look closely at the daisy, you will see in what this crowding consists. The common flower-stalk is flattened out at the end into a regular disk, and on this disk all the florets are seated with no appreciable separate flower-stalks of their own. Outside them a double row of leaves is arranged, exactly like the calyx in single flowers, and serving the same protective purpose—to preserve the florets from the incursions of unfriendly insects; while inside, the little individual blossoms have almost lost their own calyxes which are scarcely represented by a few tiny protuberances upon the seed-like fruit. In the daisy, indeed, we may say that the true calyx has been dwarfed away to nothing; but in the dandelion and many other composites a new use has been found for it; it has been turned into those light feathery hairs which children call ‘the clock,’ and which aid the dispersion of the seeds by wafting them about before the wind.

Now, what has made the daisy and the other composites grow so small and thick-set? Probably the need for attracting insects. By thus combining their mass of bloom they are enabled to make a great show in the world, and to secure the fertilisation of a great many flowers at once by each insect which visits the head. For each floret has its own little store of honey, its own stamens, and its own pistil containing an embryo fruit; and when a bee lights upon a daisy head, he turns round and round, extracting all he can get from every tiny tube, and so fertilising the whole number of florets at a single time. The result at least proves that the principle is a good one; for few flowers get so universally fertilised, or set their seed so regularly, as the composites. Though they must have reached their present very high state of evolution at a comparatively recent period, they have spread already over the whole world; and they are far more numerous, both in individuals, in species, and in genera, than any other family of flowering plants. In fact, they are undoubtedly the dominant tribe of the whole vegetable kingdom. When I say that in Britain alone they number no less than 120 species, including such common and universal weeds as the daisy, dandelion, thistles, groundsel, camomile, milfoil, hawkweed, and burdock, it will be clear that nine out of every ten ordinary wayside blossoms which we see on any country walk are members of this highly evolved, ubiquitous, and extremely successful family.

Still, we are far from having finished the pedigree of the daisy. We have traced its general genealogy down as far as the common composite stock: we have now to trace its special derivation from the early common composite type to the distinctive daisy form. Clearly one great point in the daisy’s history is yet untouched upon; and that is the nature and meaning of the white rays. We know that the inner yellow florets are (as it were) dwarfed and specialised golden harebells; but we do not yet know what is the origin of these long outer streamers, which look so wholly unlike the tiny and regular central bells.

In solving this problem, the other composites will help us not a little; for we must always seek in the simpler for the interpretation of the more complex; and the daisy, instead of being the simplest, is one of the most developed representatives of the composite pattern. If you turn to that tall, rank-looking weed growing yonder, under cover of the hedge, you will get a good surviving example of the earliest form of composite. The weed is a eupatory—‘hemp agrimony’ the country people call it—and it has small heads, each containing a few tubular purple florets, all exactly the same size and shape, and all much more loosely gathered together than in the daisy or the dandelion. The eupatory is interesting as preserving for us one of the first stages in the ancestry of the higher composites, after they had attained to their distinctive family characteristics. Once more, I don’t wish you to understand that the daisies are descended from the eupatory: all I mean is, that their ancestors must once have passed through an analogous stage; and that the eupatory has never got beyond it, while the daisies have gone on still further differentiating and adapting themselves till they reached their present peculiar form. Now, if you compare this daisy with the head of eupatory, you will see that they differ in two particulars—the daisy has outer rays, while the eupatory has none; and the inner daisy florets are yellow, while the eupatory florets are purple. The latter difference is one into which we cannot enter now: it must suffice to say that when the daisy’s ancestors were in the eupatory stage of development they had apparently all their florets yellow. This is likely, because almost all the modern composites of every sort have yellow central florets, and most of them have yellow rays as well. It is only a few kinds that have red or purple central florets; and, as we shall soon see, only a few also that have white or pink outer rays.

What, then, made the daisy’s ancestors produce a row of external florets so different in shape and colour from the internal ones? The answer is exactly analogous to that which I have already given for the origin of petals themselves. Compare the eupatory with the daisy once more, and you will see that the one is comparatively inconspicuous, while the other is very noticeable and bright-coloured. The row of green bracts almost hides the blossoms of the eupatory; but the large white rays make a bold and effective advertisement for the daisy. Certain composites, in fact, have just repeated the same device by which the earliest petal-bearing flowers sought to attract the notice of insects. Those early flowers, as we saw, set apart one outer row of stamens as bright-coloured petals; these later compound flower-heads have set apart one outer row of florets as bright-coloured rays. If you examine the rays closely, you will see that each of them is a separate little flower, with the stamens suppressed, and with the bell-shaped corolla flattened out into a long and narrow ribbon. Even these very abnormal corollas, however, still retain a last trace of the five original distinct petals; for their edge is slightly notched with five extremely minute lobes, often nearly obliterated, but sometimes quite marked, and almost always more or less noticeable on a careful examination. A daisy thus consists of a whole head of tiny tubular bells, the inner ones normal and regular, with corolla, stamens, and pistil, and the outer ones flattened or ligulate, with the stamens wanting, and the entire floret simply devoted to increasing the attractiveness of the compound mass. Pull off the rays, and you will see at once what an inconspicuous flower the daisy would be without them.

Last of all, the question arises, Why are the outer florets or rays pink and white, while the inner florets or bells are golden yellow? When we have solved that solitary remaining problem, we shall have settled the chief points in the daisy’s pedigree. Clearly, when the rays were first produced, they must have been yellow like the central florets. The mere flattening and lengthening of the corolla would not in itself tend to alter the colour. And as a matter of fact, the vast mass of those composites which have progressed to the stage of having rays—which have got these two separate forms of flowers, for show and for use respectively—have the rays of the same colour as the central bells, that is to say, generally yellow. Of this stage the sunflower is a familiar and very striking representative. It has bright golden central florets, and large expanded rays of the same colour. To anybody who wants to study the structure of the daisy without a microscope, the sunflower is quite as valuable and indispensable as it is to our most advanced æsthetic school in painting and decoration. Moreover, it shows us admirably this intermediate stage, when the compound flower-head has acquired a distinct row of outer attractive florets, adding wealth and expansiveness to its display of colour, but when it has not yet attempted any specialisation of hue in these purely ornamental organs. The daisy, however, together with the camomile, the ox-eye daisy, and many other similar composites, has carried the process one step further. It has coloured its rays white, and has even begun to tinge them with pink. This makes these highest of all composites the most successful plants in the whole world. If one considers that daisies begin to bloom on January 1, and go on flowering till December 31; that they occur in almost every field far more abundantly than any other blossom; and that each one of them is not a single flower, but a whole head of flowers—it will be quite clear that they are much more numerous than any rival species. And when we add to them the other very common white-rayed composites, such as the camomiles, many of which abound almost as freely in their own haunts and at their proper season, it is obvious that this highly evolved composite type is the dominant plant race of the old world at least. In the new world, their place is taken by a somewhat more developed type still, that of the Michaelmas daisies, which have their rays even more ornamental than our own, and brightly coloured with mauve or lilac pigment. All the world over, however, in and out of the tropics, the commonest, most numerous, and most successful of plants are ray-bearing composites of one kind or another, like the daisies, with the rays differing in colour from the central florets.

Finally, it may, perhaps, at first hearing, sound absurd to say that the daisy group, including these other composites with tinted rays, forms the very head and crown of the vegetable creation, as man does in the animal creation: and yet it is none the less true. We are so accustomed to look upon a daisy as a humble, commonplace, almost insignificant little flower, that it seems queer to hear it described as a higher type of plant life than the tall pine-tree or the spreading oak. But, as a matter of fact, the pine is a very low type indeed, as is also the giant tree of California, both of them belonging to the earliest and simplest surviving family of flowering plants, the conifers, which are no better, comparatively speaking, among plants, than the monstrous saurians and fish-like reptiles of the secondary age were among animals. If size were any criterion of relative development, then the whale would take precedence of all other mammals, and man would rank somewhere below the gorilla and the grizzly bear. But if we take complexity and perfection in the adaptation of the organism to its surroundings as our gauge of comparative evolution, then the daisies must rank in the very first line of plant economy. For if we follow down their pedigree in the inverse order, we shall see that, inasmuch as they have coloured rays, they are superior to all their yellow-rayed allies (for example, the sunflower); and inasmuch as these have rays, they are superior to all rayless composites (for example, the eupatory); and inasmuch as composites generally have clustered heads, they are superior to all other flowers with separate tubular corollas (for example, the heathers); while all these, again, are superior to those with separate petals (for example, the roses); and all petalled flowers are superior to all petalless kinds (for example, the pines and oaks). Thus, from the strict biological point of view, it becomes quite clear that the daisies, asters, chrysanthemums, and other rayed composites with coloured outer florets, really stand to other plants in the same relation as man stands towards other animals. That is what gives such a special and exceptional interest to the daisy’s pedigree.