I had never chanced to read of this flower in the literature of cross-fertilization, and murmuring, half aloud, "What pretty mystery is yours, my Collinsonia?" prepared to investigate.
[Ill.u.s.tration: Fig. 9]
What I observed is pictured severally at Fig. 9, the flowers being shown from above, showing the two spreading stamens and the decidedly exceptional unsymmetrical position of the long style extending to the side. A small nectar-seeking b.u.mblebee had approached, and in alighting upon the fringed platform grasped the filaments for support, and thus clapped the pollen against his sides. Reasoning from a.n.a.logy, it would of course be absolutely clear that this pollen has thus been deposited where it will come in contact with the stigma of another flower. So, of course, it proved. In the bee"s continual visits to the several flowers he came at length to the younger blooms, where the forked stigmas were turned directly to the front, while the immature stamens were still curled up in the flower tubes. Even the unopened buds showed a number of species where the early matured stigma actually protruded through a tiny orifice in precisely the right position to strike the pollen-dusted body of the bee, as he forced his tongue through the tiny aperture.[A]
[Footnote A: In numerous instances observed since the above was written I have noted the larger b.u.mblebees upon the blossom. These insects have a different method of approach, hanging beneath the flower, the anthers being clapped against their thorax at the juncture of the wings, instead of the abdomen, as in the smaller bee.]
[Ill.u.s.tration]
If their dainty mechanism excite our wonder, what shall be said of the revelations in the great order of the Compositae, where each so-called flower, as in the dandelion, daisy, cone-flower, marigold, is really a dense cl.u.s.ter of minute flowers, each as perfect in its construction as in the examples already mentioned, each with its own peculiar plan designed to insure the transfer of its own pollen to the stigma of its neighbor, while excluding it from its own?
All summer long the cone-flower, Fig. 10 (_Rudbeckia hirta_), blooms in our fields, but how few of us imagine the strange processes which are being enacted in that purple cone! Let us examine it closely. If we pluck one of the blossom"s heads and keep it in a vase over-night, we shall probably see on the following morning a tiny yellow ring of pollen encircling the outer edge of the cone. In this way only are we likely to see the ring in its perfection, as in a state of nature the wind and insects rarely permit it to remain.
[Ill.u.s.tration: Fig. 10]
If we now with a sharp knife make a vertical section, as shown at A (Fig. 3), we may observe the conical receptacle studded with its embryo seeds, each bearing a tiny tubular blossom. Three distinct forms of these flowers are to be seen. The lower and older ones are conspicuous by their double feathery tails, the next by their extended anthers bearing the pollen at their extremity, and above these again the buds in all stages of growth. These various states are indicated in Fig. 11.
As in all the Compositae, the anthers are here united in a tube, the pollen being discharged within. At the base of this anther-tube rises the pistil, which gradually elongates, and like a piston forces out the pollen at the top. Small insects in creeping over the cone quickly dislodge it. In the next stage the anthers have withered, the flower-tube elongated, and the top of the two-parted pistil begins to protrude, and at length expands its tips, disclosing at the centre the stigmatic surface, which has until now been protected by close contact.
(See section.)
[Ill.u.s.tration: Fig. 11]
A glance at Fig. 11 will reveal the plan involved. The ring of pollen is inevitably scattered to the stigmas of the neighboring flowers, and cross-fertilization continually insured. Similar contrivances are to be found in most of the Compositae, through the same method being variously applied.
Perhaps even more remarkable than any of the foregoing, which are more or less automatic in their movements, is the truly astonishing and seemingly conscious mechanism displayed in the wild arum of Great Britain--the "lords and ladies" of the village lanes, the foreign counterpart of our well-known jack-in-the-pulpit, or Indian-turnip, with its purple-streaked canopy, and sleek "preacher" standing erect beneath it. A representation of this arum is shown in Fig. 12, and a cross section at A, properly indexed.
[Ill.u.s.tration: Fig. 12]
How confidently would the superficial--nay, even careful--examination of one of the old-time botanists have interpreted its structure: "How simple and perfect the structure! Observe how the anthers are placed so that pollen shall naturally fall directly on the stigmas and fertilize them!" Such would indeed appear to be intended, until it is actually discovered that the _stigmas have withered_ when the pollen is shed--a device which, acting in a.s.sociation with the little ring of hairs, tells a strange story. It is not my fortune to have seen one of these singular blossoms, but from the description of the process of fertilization given in Hermann Muller"s wonderful work, aided by a botanical ill.u.s.tration of the structure of the flower, I am readily enabled to picture the progressive stages of the mechanism.
[Ill.u.s.tration: Fig. 13]
In the first stage (B, Fig. 13) small flies with bodies dusted with pollen from a previous arum blossom (for insects, as a rule, remain faithful or partial to one species of flowers while it is in bloom) are entering the narrowed tube, easily pa.s.sing through the drooping fringe of hairs. Nectar is secreted by the stigmas, and here the flies a.s.semble, thus dusting them with pollen. Their appet.i.te temporarily satisfied, the insects seek escape, but find their exit effectually barred by the intruding fringe of hairs (C). In this second stage the stigmas, having now been fertilized, have withered, at the same time exuding a fresh supply of nectar, which again attracts the flies, whereupon, as shown at D, the anthers open and discharge their pollen upon the insects. In the fourth stage (E), all the functions of the flower having now been fulfilled, the fringe of hairs withers, and the imprisoned pollen-laden flies are permitted to escape to another flower, where the beautiful scheme is again enacted.
In a paper of this kind it is of course possible only to hint at a few representative examples of floral mechanisms, but these would be indeed incomplete without a closing reference to that wonderful tribe of flowers with which the theory of cross-fertilization will ever be memorably a.s.sociated. I have previously alluded to the absolute dependence of the red clover upon the b.u.mblebee. This instance may be considered somewhat exceptional, though numerous parallel cases are known. Among ordinary flowers this intervention of the insect is largely a _preferable_ intention, and though almost invariably fulfilled, a large proportion of flowers still retain, as a _dernier ressort_, the power of at least partial self-fertilization and perpetuity in the absence or neglect of their insect counterpart.
[Ill.u.s.tration: Fig. 14]
The numerous and conclusive demonstrations of Darwin, however, have proved that in the compet.i.tion for existence such self-fertilized offspring quickly yield before the progeny of cross-fertilization.
But the distinctive feature of the orchids lies in the fact that this dependence on the insect is wellnigh universally absolute. Here are a great host of plants which are doomed to extinction if for any reason their insect sponsors should permanently neglect them. The princ.i.p.al botanical feature which differentiates the orchid from other plants lies in the construction of the floral organs, the pistil, stigma, and anthers here being united into a distinct part known as the column. The pollen is, moreover, peculiar, being collected into more or less compact ma.s.ses, and variously concealed in the flower. Some of these are club-shaped, with a viscid extremity, others of the consistency of a sticking-plaster, and all are hidden from external view in pouches and pockets, from which they never emerge unless withdrawn on the body of an insect. The various devices by which this removal is insured are most astonishing and awe-inspiring. Nor is it necessary to go to the conservatory for a tropical specimen, as is commonly supposed. An orchid is an orchid wherever it grows, and our native list of some fifty species will afford examples of as strange mechanical adaptations as are to be found among Darwin"s pages. Indeed, a few of our American species are there described. One example will suffice for present ill.u.s.tration--the sweet-pogonia or gra.s.s-pink of our sedgy swamps (_Pogonia ophioglossoides_). Its solitary rosy blossom, nodding on its slender stem above the sedges, is always a welcome episode to the sauntering botanist, and its perfume, suggesting ripe red raspberries, is unique in the wild bouquet. One of these flowers is shown in profile at Fig. 14, its various parts indexed. Concealed behind the petals is the column, elsewhere indicated from various points of view. Attracted by its color and fragrance, the insect seeks the flower; its outstretched fringy lip offers a cordial invitation at its threshold, and conducts its visitor directly to the sweets above. In his entrance, as seen at D (Fig. 15), the narrowed pa.s.sage compresses his back against the underside of the column, forcing his head and back against the stigma. The effect of this inward pressure, as will be seen, only serves to force the anther more firmly within its pocket; but as the insect, having drained the nectar, now backs out, note the result. The lip of the anther catches upon the back, swings outward on its hinge, and deposits its sticky pollen all over the insect"s back, returning to its original position after his departure. In another moment he is seen upon another blossom, as at D again, his pollen-laden back now coming in contact with the stigma, and the intention of the blossom is accomplished; for without this a.s.sistance from the insect the little lid remains close within its pocket, and the pollen is thus retained.
[Ill.u.s.tration: Fig. 15]
What startling disclosures are revealed to the inward eye within the hearts of all these strange orchidaceous flowers! Blossoms whose functions, through long eras of adaptation, have gradually shaped themselves to the forms of certain chosen insect sponsors; blossoms whose chalices are literally fashioned to bees or b.u.t.terflies; blossoms whose slender, prolonged nectaries invite and reward the murmuring sphinx-moth alone, the floral throat closely embracing his head while it attaches its pollen ma.s.ses to the bulging eyes, or perchance to the capillary tongue! And thus in endless modifications, evidences all of the same deep vital purpose.
Let us then content ourselves no longer with being mere "botanists"--historians of structural facts. The flowers are not mere comely or curious vegetable creations, with colors, odors, petals, stamens, and innumerable technical attributes. The wonted insight alike of scientist, philosopher, theologian, and dreamer is now repudiated in the new revelation. Beauty is not "its own excuse for being," nor was fragrance ever "wasted on the desert air." The seer has at last heard and interpreted the voice in the wilderness. The flower is no longer a simple pa.s.sive victim in the busy bee"s sweet pillage, but rather a conscious being, with hopes, aspirations, and companionships. The insect is its counterpart. Its fragrance is but a perfumed whisper of welcome, its color is as the wooing blush and rosy lip, its portals are decked for his coming, and its sweet hospitalities humored to his tarrying; and as it finally speeds its parting affinity rests content that its life"s consummation has been fulfilled.
_A HONEY-DEW PICNIC_
[Ill.u.s.tration]
Several of our notable as well as notorious human, social, and civic customs find their prehistoric prototypes in the insect kingdom. The monarchical inst.i.tution sees its singular prophecy in the domestic economy of the bees. War and slavery have always been carried on systematically and effectually by ants, and, according to Huber and other authorities, agriculture, gardening, and an industry very like dairy farming have been time-honored customs among this same wise and thrifty insect tribe, whose claims to thoughtful consideration were so long ago voiced by Solomon of proverbial fame. Thevenot mentions "Solomon"s ant" as among the "beasts which shall enter paradise."
Indeed, the human saint as well as sluggard may "go to the ant" for many suggestive hints and commentaries.
These are only a few of the more notable parallelisms which suggest themselves. But others are not wanting if we care to follow the subject.
In addition to the many models of thrift and virtuous industry, embodying types of many of the trade employments known to humanity, have we not also among these "meadow tribes" our luxurious "idlers" and "exquisites," the b.u.t.terflies and flower-haunting flies and "dandy"
beetles; and, opposed to all these, the suggestive ant.i.thesis of the promiscuous marauders, thieves, and brigands everywhere interspersed?
Thus we have our individual insect a.s.sa.s.sin and a.s.sa.s.sination organized in war; so, on the other hand, have we our insect merrymakers; why not, then, our picnic or carnival?
Such I am moved to call the singular episode which I observed last summer, and which I have endeavored to picture as true to the life as possible in the accompanying presentment The sceptic will perhaps remark on examination that the scene is characterized by somewhat too free a license to warrant the ideal of a "picnic." But he is hypercritical. There are picnics and picnics--picnics of high and of low degree. Do I not recall more than one notorious festive outing of the "next lower than the angels" in which the _personnel_ seemed about similarly proportioned, and the fun and attraction comparatively related to the license?
One July afternoon a year ago I was returning home from one of my botanizing strolls. I had just emerged from a deep wood, and was skirting its border, when my attention was caught by a small fluttering swarm of b.u.t.terflies, which started up at my approach and hovered about a blossoming blackberry bush a few yards in advance of me at the side of my path. The diversity of the b.u.t.terfly species in the swarm struck me as singular, and the mere allurement of the blackberry blossoms--not usually of especial attraction to b.u.t.terflies--could hardly explain so extensive a gathering. Here was the great yellow swallow-tail (_Turnus_), red admiral (_Atlanta_), small yellow b.u.t.terfly (_Philodice_), white cabbage-b.u.t.terfly, comma and semicolon, and numerous small fry, fluttering about me in evident protest against my intrusion. They showed no inclination to vacate the premises, so, in pursuance of one of the first articles of my saunterer"s creed, I concluded to retreat softly a few paces and watch for developments. One by one the swarm sought their original haunt, settling on the bramble, and I now noticed that only in occasional instances did the insects seek the flowers, the attraction seeming to be confined to the leaves. I stole up softly for a nearer point of observation, and could now distinctly see the beautiful yellow and black open wings of the swallow-tail softly gliding or gently fluttering as it hung from the edge of a leaf, while it explored its surface with its uncoiled capillary tongue. Just beyond my _Turnus_, on another leaf, I now noted a new presence, the orange Aphrodite b.u.t.terfly, silvery spotted, its nether wings being folded over its back, too much absorbed to have been startled by my first approach. Occasionally, without any cause which I could detect from my present position--certainly in no way connected with my presence--a small swarm of the b.u.t.terflies would rise in a flutter above the bush, as though actuated by a common whim--a brief winged tangle in which a beautiful sprite of velvety black hovering in a globular halo, shot through with two white semicircular arcs, was always a momentary feature.
Carefully stealing through the tall gra.s.s, I now approached to within touching distance of the haunt, and was soon lost in mingled wonder, amus.e.m.e.nt, and surprise at the picnic now disclosed, the occasional b.u.t.terfly swarm being now easily explained. From my first point of view only the top of the bramble spray was visible above the gra.s.s, and by far the most interesting portion of the exercises had been concealed from view. The b.u.t.terflies, while naturally the most conspicuous element, were now seen to be in a small minority among the insect gathering, the bramble leaves being peopled with a most motley and democratic a.s.semblage of insects. Cla.s.s distinctions were apparently forgotten in the common enthusiasm; the plebeian bluebottle and blowfly now consorted with Aphrodite and sipped at the same drop. Many a leaf was begemmed with the blue bodies closely set side by side or in a close cl.u.s.ter. The meat-fly, house-fly, and horse-fly made themselves promiscuous in every portion of the spray, and what with the rainbow-eyed and ruby-eyed flies, black and silver-banded flower-flies, and other tiny, restless, iridescent atoms of the fly fraternity, the family of _Musca_ was well represented at the feast.
Nor were these all the guests at the banquet--for banquet there certainly was, judging from the eager sipping and crowding everywhere upon the leaves, the flowers even yet, as I first noticed, seeming to have little attraction.
I have no direct means of knowing as to the social discrimination of the host as shown in the entertainment, for that invitations were issued the subsequent facts would show. But I have good reasons for believing, from the course of events, that the gathering included a number of questionable personages that were not counted upon.
Here, for instance, was an overwhelming contingent of the whole tough gang of wasps and hornets--brown wasps from under the eaves and fences; black hornets from the big paper nests; yellow-jackets from where you please; deep steel-blue wire-waisted wasps from the mud cells in the garret, to say nothing of an occasional longer-waisted digger-wasp, and a host of their allied lesser a.s.sociates scattered around generously among the a.s.semblage.
Every now and then a big darning-needle took a shimmering circuit about the bush, and doubtless knew what he was about; as did also what at first glimpse appeared to be a big b.u.mblebee, which seemed to find attraction in the neighborhood, although he seldom alighted upon the leaves, preferring to sit upon a neighboring weed and watch his opportunities.
I have thus described a few of the more prominent guests or personages present at the feast. But I have reported little of their "goings on."
Doubtless there were appropriate toasts and responses, or what in bug etiquette answered to this seemingly indispensable human fad, while as to that other festive social essential of after-dinner speeches, coupled in this case with most vigorous discussion, I am certain the air was blue with something of this sort, if the eloquent pantomime bore any significance. Here, for instance, is one isolated, but frequent, episode. A peaceable little group of plain bluebottle-flies, with but a single thought, are all sipping at the same drop in contentment. A brief respite, for now the tips of a pair of inquisitive antennae appear from the under edge of the leaf upon which they are sipping, and gingerly explore the upper surface. They are quickly followed by the covetous almond-eyed gaze of a brown wasp, that now steals cautiously around to the upper surface, and appears wholly engrossed in licking the leaf.
Nearer and nearer he sidles up to the group of flies, and now with deliberate purpose and open jaws makes a dash among them. But they are too quick for him, and are away in a glittering blue tangle, which finally concentrates itself upon a neighboring leaf, where the eager tippling is immediately resumed. The wasp now holds the fort, and seems in no mood to be trifled with. With head and fore feet upraised and open jaws he seems "spoiling for a fight," and ready to make war upon the first comer. But no, he is evidently expecting a friend that, I now observe, approaches him determinedly down the stem of the leaf. The new-comer, a brown wasp like himself, is now at close range, and in an instant more, without any visible courteous preliminaries, the two set upon each other with a common enthusiasm, and with jaws working and stings fencing the interlocked combatants fall to the ground for a finish. I presume the affair was carried to the fourteenth round without any undue interference.
Another and another of these friendly meetings between them and other wasps took place in the half-hour in which I watched the sport. There were lulls in hostilities, during which an atmosphere of perfect peace and harmony seemed to reign around my bramble-bush. The flies were motionless in their ecstasy, and the hornet element seemed by common consent to keep temporarily shady, and even the b.u.t.terflies seemed to forget that they had wings. But not for long, for now with a shimmering glitter our darning-needle invades the scene, and retires to a convenient perch with a ruby-eyed fly in his teeth, while a swarm of very startled b.u.t.terflies tells conspicuously of the demoralization which he has left in his path. Among the b.u.t.terfly representatives I at length observed one individual which at first had escaped me, an exclusive white cabbage-b.u.t.terfly which sipped quietly at his leaf in the shade, and seemed to take little interest in the disreputable actions of his a.s.sociates. Nothing could move him or entice him away from his convivial employment. But, alas! his folly soon found him out, for, on happening to look again, I observed he had found a new acquaintance--a hornet that had evidently been long desirous of meeting him. One by one I saw my b.u.t.terfly"s dismembered wings fall to the gra.s.sy jungle below, while a big black wasp proceeded to enjoy the collected sweets which he had doubtless observed were being so carefully stored away there in the shady retreat.
[Ill.u.s.tration]
And now my pretty black b.u.t.terfly--no, it proved to be the little day-flying grape-vine-moth, the eight-spotted black _Alypia_--appeared from some unseen source, and spun his c.r.a.py white-streaked halo among the leaves, at length settling among a little company of flies. Softly behind him creeps a brown wasp (_Polistes_), with his mouth watering, while from the opposite quarter a steel-blue mud-wasp approaches, with apparently similar designs. Neither invader sees the other.
Simultaneously, as though answering to a signal, the two make a dash at the moth; but he is too quick for them. In a twinkling he is off in his pretty halo again, while the two disappointed contestants have clinched, and with stings and jaws vigorously plying fall to the jungle below, and seek satisfaction in mortal combat.
Here is a pretty little yellow and black banded flower-fly, which is having a quiet little picnic all by himself on a bed of yarrow bloom close by. But a big black paper-hornet has suddenly seen an attraction hither also, and is soon creeping stealthily among the blossoms with a wild and hungry look. But the hornets seemed to waste their time on the flies. Seemingly confident in their less complicated wing machinery, the two-winged fly rarely sought escape until within very close range of his enemy, and his resources never seemed to disappoint him at the critical moment.
Among the insect a.s.semblage was a large number of ants of all kinds and sizes, the common large black species being conspicuous. Here is one creeping and sipping along a gra.s.s stem. A small digger-wasp likes this gra.s.s stem too, but instead of exchanging courtesies on the subject, the wasp proceeds to bite the ant"s head off without ceremony, and continues sipping at the stem as though decapitation were a mere casual incident in its daily walk.
On the same stem a big blowfly has alighted. Judging from appearances, he has had his fill of good things, and is now making his leisurely toilet in the peculiar fashion of his kind, rubbing down his back and wings with his hind legs, twisting his front feet into spirals, and ever and anon testing the strength of his elastic neck attachment as he threatens to pull his head from his body.
This worldly act has been progressing for some moments under the gaze of a big black digger-wasp, who now concludes to cut it short. When at close range with his prey, the fly suddenly discovers the unhealthy location which he occupies, and actually protruding his tongue by way of parting salute, he is off with a buzz. He has barely taken wing, however, when a still louder buzz is heard, while a great black b.u.mblebee follows closely in his wake, until the sounds of both are lost in the distance. The hum of this b.u.mblebee is a frequent musical feature of the entertainment, and many is the dance that is set to its minstrelsy, as the burly insect darts in among the merrymakers and is off to his perch near by. It is only as we steal away and observe him closely that we learn the secret of his occasional sorties. There on a clover blossom he sits--sipping honey? Oh no. It is honey-dew that he is enjoying, and second-hand at that, as he devours the satiated bluebottle-fly which is empaled on his black h.o.r.n.y beak. For this is only a b.u.mblebee in masquerade--a carnivorous fly, in truth, which, safe in its disguise of respectability, hovers in the flowery haunts of the innocents and, of course, reaps his reward.
And what is this? A yellow-jacket has found an ambrosial attraction here upon the bramble leaf. Meanwhile a great black and white paper-hornet has seen his opportunity, and is soon slyly approaching behind the sipper. That he has designs on that jacket and its contents is apparent.