A Plant that Melts Ice
( Originally Published Early 1900's )
IF you have ever visited the Alps in early spring, you will know well by sight the dainty little nodding bells of the Alpine soldanella, twin flowers on one stalk, like fairy tocsins, which push their heads boldly through the ice of the névé, and form a border of blue blossoms on the edge of the snow sheet. As the snow melts upward the flowers open in zones, one after. another, so that you can mark your ascent by the variations in flora and the different stages of development reached by the most persistent kinds at various levels.
There is one adventurous little plant, however, among these competing kinds, which in its eagerness to make the most of the short Alpine summer does not even wait, like its neighbors, for the melting of the snow, but, vastly daring, begins to grow under the surface of the ice sheet, and melts a way up for itself by internal heat, like a vegetable furnace. It may fairly be called a slow combustion stove, not figuratively, but literally. It burns itself up in order to melt the ice above it. This wonderful plant is the Alpine soldanella, the hardiest and one of the prettiest of mountain flowers ; it opens its fringed and pensile blue blossoms in the very midst of the snow, often showing its slender head above a thin layer of ice, where it fearlessly displays its two sister bells among the frozen sheet which still surrounds its stem in the most incredible fashion.
Comparatively few observers have noticed that the soldanella, fragile as it is, actually forces itself up through a solid coat of ice, not exactly by hewing its way, but by melting a path for itself in the crystal sheet above it. Yet such is really the case; it warms the ice as it goes. The buds begin to grow on the frozen soil before the ground is bare, under the hardened and compressed snow of the névé,which at its edge is always ice-like in texture. They then bore their way up by internal heat (like that of an animal) through the delicate sheet that covers them; and they often expand their delicate blue or white blossoms, with the scalloped edges, in a cup-shaped hollow above, while a sheet of refrozen ice, through which they have warmed a tunnel or canal for themselves, still surrounds their stems and hides their roots and their flattened foliage. This is so strange a miracle of nature that it demands some explanation ; the method by which the soldanella obtains its results is no less marvelous than the results themselves which it produces
The winter leaves of the soldanella, which hibernate under the snow just as truly as the squirrel or the dormouse hibernates in its nest, are large, healthy, tough and evergreen. They are, in fact, just living reservoirs of fuel (like the fat of the dormant bear), which the plant lays by during the heat of summer in order to burn it up again in spring for the use of its flowers. When I use this language, you will think at first I am speaking figuratively. But I am not; I mean it in just as literal a sense as when I say that the coal in the tender of a loco-motive serves as fuel for the engine, or that the corn in the bin of a stable serves as fuel to heat the horse's body. These leaves contain material laid by for burning; and it is by burning that material up at the proper period that the soldanella manages to melt its way out of the wintry ice sheet, and so to steal a march upon competing species.
The process requires explanation, I admit; let us try to understand it. Everybody knows, as a matter of common experience, that animals are warmer in winter than the air which surrounds them, warm-blooded animals, that is to say, which form the only class that most people trouble about. Not everybody knows, however, that the same thing is more or less true of plants as well—that many plants have the power of evolving heat for themselves in considerable quantities. But this is actually true; indeed, all growing parts of a stem or young leaf-shoot must necessarily be slightly warmer than the air around them. All growing shoots combine with oxygen and therefore, rise in temperature. In early spring, when the ground just teems with sprouting seeds and swelling buds, with growing bulbs, or shooting tubers, the temperature of the soil is sensibly raised ; and this very heat, evolved by germination, becomes itself in turn a cause of more germination; each seed and bulb and root and sucker helps to warm and start all the others. Spring largely depends upon the warmth thus produced. The earth, during this orgy of growth, is warmer by a good deal than the air about it; warmer even than it is in summer weather-indeed, were it not for the number of plants which thus start growing at once, growth would be almost impossible in very cold countries. Like roosting fowls, they warm one another.
At the risk of seeming tedious in this preliminary explanation, I must also add that flower buds and flower stems which grow and open very rapidly must similarly use up oxygen in their growth, and therefore rise in temperature. In a very few large and conspicuous flowers, such as the big white calla lily, this rise in temperature during the flowering period can be measured even with an ordinary thermometer. No bud can open without giving out heat; and the amount of heat is sometimes considerable.
And now, I hope, we are in a position to understand how soldanella acts, and why it does so. It has to eke out a livelihood in the mountain belt, just below the snow line; and it is a low-growing type, which must flower early or else it would soon be overshadowed by taller rivals. For growth is rapid in the Alps once the snow has melted. Soldanella has thus to blossom and to secure the aid of its insect fertilizers, at the precise moment when they emerge from their cocoons in the first warm days of the short Alpine summer. If it waited later it would be overtopped and obscured in a very few days by the dense and rapid growth of waving grasses, and aspiring globe-flowers, and long-stalked, bulbous plants that crowd all around it. So the soldanella seizes its one chance in life at the earliest possible moment, and makes haste to pierce its way through the solid ice sheet while lazier rivals passively await its melting. That alone has secured its survival and success in the crowded world of the Alpine pastures. For you must not forget that while to you and me the Alps are an unpeopled solitude, to the Alpine plants they are a veritable London of competing life-types.
The canny plant lays its plans deep, too, and begins well before hand. It has made preparations. All the previous summer it has been spreading its round leaves to the mountain sun, and laying by material for next year's flowering season. Leaves, you know, are the mouths and stomachs of plants; and the soldanella has a type of leaves admirably adapted to its peculiar purpose : expanded in the sunlight, they eat carbon and hydrogen the livelong summer, and turn the combined oxygen loose upon the air under the influence of the sun. By the time winter comes, they are thick and leathery, filled with fuel for the spring, and, of course, evergreen. They have also long stalks which enable them during the slimmer to stretch up into the light, but in autumn they descend and flatten themselves against the soil, so as not to be crushed by the snows of winter.
The material laid by in the thickened leaves consists of starches, protoplasm, and other rich foodstuffs. The snow falls and the leaves, protected by their hard and leathery covering, remain unhurt by it. The food and fuel they have gathered is stored partly in the foliage and partly in the swollen underground root stock. All winter through, the plant is thus hidden under a compact blanket of snow, which becomes gradually hard and ice like by pressure. But as soon as the spring sun begins to melt the surface at the lower edge of the sheet, water trickles down through cracks in the ice and sets the root stock budding. The soldanella has collected its material deliberately as fuel, and uses it up on purpose to melt its passage. It absorbs oxygen from the air beneath the snow, combines it with the fuels in its own substance, evolves heat from their combination, and begins to send up nodding flower buds through the icy sheet that spreads above it.
The warmth the plant obtains by this curious process of slow, internal combustion, it first employs to melt a little round hole in the ice for its arched flower buds. At the beginning, the hollow which is formed above each pair of buds is hemispherical or dome shaped; the stem pushes its way up through a dome of air enclosed in the ice; and the water it liberates trickles down to the root, thus helping to supply moisture for further growth with its consequent heating. But by and by the stem lengthens and the bud is raised to a considerable height by its continuous growth. Still, so slight is the quantity of heat the poor little plant can evolve with all its efforts, that by the time the stem is an inch or two long, the lower part of the tunnel has curiously frozen over again.
In this stage, then, the melted space is no longer a dome; it assumes the form of a little balloon or round bubble of air, surrounding the flower bud. At the same time, the ice underneath, having frozen again, almost touches the stem, so that the bud seems to occupy a small clear area of its own in the midst of the sheet, with ice above, below, and all round it.
Gradually, in this way, the little buds manage to bore their way to the surface and to the sunshine on the out-side of the ice sheet. At last the stalk melts its path out, and a flower appears on the top, in the center of a small, cup-shaped or saucer-shaped depression. The exquisite blue bells are thus seen blooming in profusion, apparently out of the ice itself, or as if stuck into it.
If you look at the foliage on the bare ground beneath you will find that, when the flowers open, the leaves are no longer thick and swollen. All the fuel they contained has by this time been burned up for warmth; all the formative material has been duly employed in making the buds or blossoms, with the stems that raised them; and nothing now remains but drained and flaccid skeletons from which every particle of living matter has been withdrawn and utilized. Later on new leaves are produced in turn from the root stock, after the ice has melted; and these new leaves, raising themselves on their long stalks, and catching the sunlight, begin afresh to accumulate material for next year's growth and next year's burning.
But why do the flowers want so much to reach the open air at all? Why should they not blossom contentedly under the enclosing ice sheet? Flowers, after all, are mere devices for the fertilization of the fruit ; it is the seeds and the next generation that the plant itself is mainly thinking about. The plant wants its blossoms to attract the early spring bees and honey-sucking flies, which carry pollen from head to head, and so fertilize its seeds for it. And fertilization, to the practical minded plant, is the whole root of the question.
At the very same time that the soldanella raises its timid flowers, the bees and flies a little lower down the mountain sides are just escaping from their cocoons as full fledged winged insects. It is for their sakes alone that the pensive blossoms tint themselves in blue or violet, for you will find throughout nature that blue is the true bee color; and flowers that depend most for fertilization on bees or their allies are almost always decked out in blue or purple.
Sometimes, however, the ice sheet above is too thick to pierce, and then the bud, after making manful efforts to melt its way out to the open air, is forced to give up the attempt in despair, and unfold its petals within its icy cavern. In that case, of course, no insect can visit it; and such cloistered blossoms are therefore obliged to have recourse to the inferior expedient of self-fertilization. I say inferior, because all higher plants strive as far as possible to produce seedlings which shall be the offspring of a distinct father and mother. It is in order to prevent such disastrous results on a large scale that the soldanella has invented its curious device for pushing its way boldly through its native ice sheet to the sky and the insects.
In the struggle for existence, every point of advantage any creature possesses must tell in its favor, and the soldanella has thus been enabled to hold its own bravely in the intermediate belt at the margin of the ice field. But its limits are narrow. In the open ground it is soon lived down by more hardy kinds, which rise higher into the air; its range is entirely bounded by a narrow belt just where the ice is melting. Above that point it can-not grow; below it taller enemies soon oust and dispossess it. It utilizes its short time between these two impossibilities.
Strange as it sounds, too, the ice itself acts as a sort of protective blanket or coverlet to the trustful soldanella. Only a plant that could pierce the ice could ever have hit upon such a paradoxical mode of warming itself by its own internal combustion. If an herb that flowers in the open were to make experiments in warming itself in the same manner, its attempt would necessarily fail, because as fast as it heated the air the wind would blow the heated portion away, and the plant would therefore derive no benefit from its expenditure of fuel. But we all know how Eskimos can live in a snow hut, keeping it warm inside by their own breath and the heat of their bodies. It is just the same in principle with the soldanella's cave. The little dome or cavern gets warmed within by the respiration of the flower bud, and the heat thus produced is retained within the walls of the cavity. It is almost as though a mouse or other small animal were to try to bore a path for itself through an ice barrier, not by gnawing the ice, but by breathing upon it slowly till it melted.
See, then, how absolutely the soldanella behaves like a man who is making a conservatory. It lays by fuel for the stove in its leaves to keep its flower buds warm and to force them in spring at a time when they could not blossom without the artificial heat thus supplied them. It keeps in this heat within a transparent covering, the doors of which are never opened. As for light, that reaches it through the crystal summit. But it employs the heat also to bore its way out ; and, as its ultimate object is to get its young seeds fertilized, it finally pushes its flowers out into the open air, where they may receive the attentions of the fertilizing insects, just as the gardener does, without knowing why, when he wishes seed set. The pendent, bell-shaped blossoms again, even after they are open, are admirably adapted for keeping in the heat; and they are also exactly fitted to the shape and size of the bees and flies that act as their chartered carriers of pollen. A plant, in short, has to accommodate itself at every point to the needs of its situation; it has to secure for itself a firm foothold in the soil, and a due share of food from the surrounding air (for its diet after all is chiefly gaseous) ; it has to take care that its pollen shall be duly dispersed, and its seedlets fertilized; and finally, it has to see that its young are satisfactorily settled in the world, and deposited on likely spots where they can germinate to advantage. It must be a good parent as well as a prudent and cautious adventurer.
The struggle for life carried on under these circumstances has sharpened the wits of plants to a far higher degree than most people imagine. Plants have developed almost as many dodges and devices for securing food or avoiding enemies as animals' themselves have; and this single instance enables us to see with what forethought and cleverness they often provide against adverse chances, Soldanella, indeed, could not exist at all upon its ice-clad heights if it did not lay up food and fuel in summer against the needs of winter, like the bee and the ant; if it did not burn up its own fat for warmth like the dormouse; if it did not tunnel the ice as the mole tunnels the earth; if it did not retire beneath the snow sheet on the approach of winter as the queen wasp re-tires into the shelter of the moss when frosts begin to kill her worker sisters, or as the squirrel retires into his hole in a tree at the approach of December. Ancestral instinct teaches the one just as much as it teaches the other; and those who have closest watched the habits and manners of plants have the highest respect for their industry and intelligence.
Looked at from this point of view, we may consider indeed that every seed, bulb, or tuber, is not merely a reservoir of material for future growth, but also a reservoir of fuel for supplying the heat necessary to the first stages of sprouting or germination. And without elaborating this question further, I may add that if you will examine closely many early spring buds and flowers, especially such as willow and hazel catkins, you will find not only that they are formed over winter and enclosed in warm overcoats to protect them from the cold, but also that they grow in spring before the air is warm enough to stimulate growth directly,—or in other words, that they depend in part for heat upon the consumption -of their own internal fuels.