Let Us Now Produce a New Pink Daisy
A Practical Lesson In Harnessing Heredity
An architect, in selecting the materials for his structure, sends for limestone to Bedford, Indiana, or for marble to Carrara, Italy, or for bricks to Haverstraw, N. Y., or for redwood rustic to California. In the process of turning his blue print into a building, he draws on the whole world-a little here and a little there-for his supplies. So, too, in the production of a new plant on which we wish to try our architectural skill, we must first seek out the things with which to build. Only our search will be not a search for substances, but a search for stored up heredities-not a search for bricks or stone or lumber, but a search for living traits.
The sturdy dandelions in our vacant lots, with their parachute-like seed balls, reveal a structural ingenuity and a fitness to survive which may have cost ten thousand generations of patient struggle. The sweetness of our cherries, our grapes, our plums, has been developed only through ages and ages of response to environment, with some environments so oft repeated that they have hardened into heredity. The flowers on our lawns may have acquired their colors in Germany, or in Ecuador, or in Siberia; our nuts reflect flavors picked up through a world-wide migration; and even our early vegetables show traits which hark back to times before animals and men came into their lives. So, just as the earth has stored up limestone in Indiana, and marble in Italy, and brick-clay in New York, and ten-thousand-year-old redwoods in California, for the architect to draw upon, just so, in a world full of plants, representing an infinity of ancestry with its infinity of heredity, will we find an infinity of traits with which to build. If we wish to change the color of a flower, or its scent, or its size, or its adaptability to climate-if we have it in mind to transform a tree or its fruit, or to give any plant a new trait or a new habit-the most practical way is to dig the quality we want out of the mass of heredity about us.
"I thought," says some one, "that plants could be transformed merely by changing the environments in which they grow." "So they can," replies Mr. Burbank, "if time is no object. But the quick and economical way is to take advantage of the combined environments of the past which are at our instant disposal; to short-cut to our result by using well established traits and thoroughly formed habits, rather than to spend the years or lifetimes which might be necessary to produce new traits and new habits from the beginning. It is better to seek out, first, what nature has stored away for us, and then to use new environments to improve or intensify traits and habits which already have the advantage of several centuries of start. It is the same principle of economy which we apply to everything we do. So long as there is plenty of coal within easy reach it does not pay us to build machines to utilize the energy of the sun's rays or of the ocean tides. And, similarly, so long as there are untold thousands of plants embodying, in some form, almost every conceivable trait we might desire-untold thousands of plants like the cactus waiting only our attention to make them useful-we can hardly afford to waste time in doing what nature already, laboriously, has done. The hard part, always, is to make the start. We who are late sleepers, for example, know the weeks of discouraging attempts it takes to fix the habit of arising at seven instead of eight, or at six instead of seven. Yet, once we have thoroughly accustomed ourselves to the new hour of awakening, it is just as difficult to get back to the old hour as it was to get away from it. It is as if the tendencies within us, having accommodated themselves to each other and to our surroundings, cling together tenaciously to maintain the equilibrium between themselves; when we change our surroundings they adjust themselves to the change with difficulty; but once adjusted, hold together as firmly again as they held before. So in plant life; when we transplant a flower or a tree, it shows signs, in accommodating itself to its new surroundings, of evident distress; it looks sickly, its leaves droop, it gives many outward proofs of the inward struggle which it is undergoing. As soon, however, as its suddenly scattered tendencis have collected themselves, the plant begins an era of immediate improvement, and does as well or better than it did before transplanting-as well, in fact, as its new surroundings will permit. If new habits are hard to start, new traits are harder. It is hard to teach a plant to twine when it has never twined before, or to persuade- it to be pink when it has always been yellow; just as it is hard to get a boy interested in the study of law when his likes, all his life, have been along the lines of engineering or mechanics. In the establishment of a new trait, in fact, the whole motion of life must be interrupted, its momentum arrested, the resulting inertia overcome, and new momentum in a new direction gained. But, if every difficulty has its recompense, we are well repaid for the labor of acquiring or instilling a new trait by the fact that, once acquired, it has a tendency of its own to increase and expand and grow. The boy who finally gets interested in law, who gets past the point where it becomes an irksome drudgery, begins, at length, to develop a steadfast love for his work so that what was to him, once, a bug-bear at last becomes an absorbing ideal. The cactus, for example, which produced its first spines with difficulty, now gets more and more spiny, although the need for spines has disappeared. Our flowers grow more beautiful, our fruits more luscious as their tendencies gain momentum. We may take it as a rule, almost, that a habit, once fixed, hardens: that a trait, once established, grows stronger and stronger. The easiest way, therefore, is to work with heredity, and not against it-to spend a month searching out a desirable trait or habit, rather than to spend a year or a decade trying to overcome an undesirable one."
And, now, to a practical experiment. From almost any seed house we may procure the seeds of two African wild flowers. One is the African orange daisy, the other a white daisy of the same family. The orange daisy is a sun-loving flower, as its beautiful, rich tint clearly testifies. The white daisy, by its whiteness, shows equally unmistakable evidence of an ancestry which has preferred the shade. "Bright colored flowers," said Mr. Burbank, "are almost invariably those which have grown in the sun. White flowers are either those which bloom at night, or which, if blooming in the day time, have stayed in the shade. "Because the sun reacts with the soil to produce bright colors, while the shade does not?" was asked. "No," replied Mr. Burbank. "I prefer to believe that the bees make the colors. The flowers which grow in the bright light need their brilliance to attract the insects; flowers in the shade are more easily observed if they are light or white in color; it is all a matter of advertising contrast; and, throughout ages and ages, each particular flower has been striving to perfect a color contrast scheme of its own. It may be that the combination of sun and soil makes possible brighter colors than the combination of shade and soil; but wind-loving plants, like corn and trees, which grow in the sun, do not bedeck themselves in colors-only the flowers which find it necessary to attract the insects. In practice, at any rate, the color of a flower is one of the reliable guides in the study of its life-history. Taking the orange daisy and its white cousin side by side, we see at once a family resemblance. The leaf formation, the root formation, the arrangement and the number of petals, the arrangement of stamens and pistils, bespeak the fact that here are two plants of a kind; one orange and one white; the white one taller a little, more graceful perhaps, and slightly less hardy; but cousins, beyond doubt, having within them many parallel strains of heredity. Let us assume, then, that the orange of the orange daisy is the heredity of ages of sunshine, and the white of the other daisy is the inheritance of ages of shade; that both started from the same point, and that one found itself growing in cleared fields, while around the other developed a forest of shade, so that, finally, as environment piled up on environment and accumulated into heredity, each flower became so firmly fixed in its own characteristics as to constitute a species, as man has chosen to call it, of its own. If we take the seeds of the African orange daisy, and plant them in the shade, they will still produce orange flowers. That is stored up heredity. No doubt, if we continued, year after year, to replant them in the shade for a century or so, they would begin to transform themselves to white as the other daisy did. If we plant the white African daisy in the sunshine, it will still give us flowers of white-the heredity of ages overbalancing the pull of immediate environment, and needing a long continued repetition of environment to balance and finally overcome it; but if we were to keep it in the sun throughout enough generations, it would, no doubt, bear us flowers of brilliant orange. Here, then, is a single plant reflecting two divergent strains of heredity-one orange, one white - one sturdy, one weak - each strain so thoroughly fixed that in a lifetime it would be impossible, through pure environment, to overthrow it. Let us next take a twenty-foot flower bed, say, divide it in the middle, plant one side solid with the orange daisies, and the other side solid with white daisies, and let the bees and the breezes mix those heredities up to produce for us the new pink daisy which we have planned to produce. Up come the orange flowers, and up come the white. The breezes and the bees carry the pollen from flower to flower; the petals fall away, and disclose the pods of fertile seed in which, for the first time, these two strains of heredities are combined. In the millions of seeds which we can beat out of these pods, there are some with the white tendencies stored away unaltered, some with the orange tendencies still predominant-some with white pulling evenly against orange to make a red, some with orange slightly stronger than white, and all of the infinity of variation in between. We shall find in those seeds the mixed tendencies not only of the two species, but of all of the families of two species, and of the individuals of those families; mixed, upset, disturbed-so thoroughly that, not only will the life history of both parents be laid bare in the resulting plants, but through the blends, new characteristics, probably never seen before, will show themselves. Here we have taken two plants which, since the beginning, have been storing up traits; each working out its owen destiny; each separated from the other, perhaps by a mountain range or a lake, and thus never before brought to a place where those heredities could combine; then in a single season, through combination, we produce the seed for a new daisy reflecting every conceivable blend of those different heredities.
When we plant this seed the following spring, we shall have pure orange daisies and pure white daisies, pink ones, purple ones, yellow ones; daisies large and daisies small; daisies with big black centers, and daisies in which the centers are colored the same as the outside edges. We shall find some a deeper orange than the orange daisy because the balance which has determined the established shade of orange has been upset. We shall find purer whites than the white daisy ever knew-as a result of the upset. We shall find daisies with petals whose color front and back is the same, and daisies with different colors inside and out. We shall, in short, find all of the old inheritances of the flower and of the combinations of them-all of the colors, scents if there be any, shapes, sizes, forms, elements of strength or weakness-uncovered before us. And between the white and the orange we have but to select the particular pink flower of our fancy. If the flower we select, perchance, showed some weakness, or if its tint were a little too light or too dark, or if for any other reason among this infinite color variation we did not find the exact result we sought, another season or another would surely bring it forth; for next year, instead of planting white and orange, we should plant a selection of our new daisies, and instead of getting a combination of two parentages, we should get a combination of combinations. Then, having secured the color called for in our original mental blue print, we might find structural improvements to make in the flower-we might want to increase its height or to lengthen the daily period of its opening, or to rearrange its petals into a more chrysanthemum-like form, or to increase or decrease the size of its center - or to accomplish any one of a number of other ideals which we may have set up for our production. So on we go, season after season, always selecting, getting one this year which bears a podful of seeds for next, with the bees and the winds anxious to carry on the work, narrowing our lines of heredity down and down and down, until finally some day-maybe fourteen months after the experiment began, or maybe fourteen years, we can say: "Here is a plant such as no nan ever saw before-here is the exact plant which we have planned."
"But will the seed of this new pink daisy," some one asks, "produce more daisies of this same kind of pink?" "Of all of the seeds of that daisy," says Mr. Burbank, "there might not be one which reproduced its parent pink. The seeds of that daisy sown together in a bed might easily show as great a variation as the seeds of the white and the orange showed when they were first planted after the bees and the winds had done their work. But that need be no discouragement. By dividing the roots of the daisy we can, in a single season, from a single plant, produce a whole bed of plants-each similar to the original plant because each, in fact, is a part of the original plant. We should, at the start, then, propagate our pink daisy by dividing the roots. We should find that for practical purposes it would thus be possible to produce all of the daisies we desired. We might never even care to make use of the seed. But if we did, by keeping our new pink daisies together year after year, in eight years, or perhaps ten or fourteen, pink being crossed with pink, and the upset equilibrium restored, we should find that we were getting seeds which came true, or nearly true, to type. You see, we upset heredity to produce variation; then we let it settle down to a balance to perpetuate the particular variation which we have chosen."
The architect can always build a second structure better than the first, and the plant improver, likewise, finds in each experiment a multitude of new suggestions for the production of still other changes or improvements. In even the handful of daisy variations which can be reproduced here, there are to be seen countless new tendencies, any one of which might lead to the perfection of a wholly different, if not a better flower. There are, of course, the variations in size-and those with the long petals show that with encouragement the flower, simply by quantity production and continued selection, might produce an offspring with blossoms three inches or four or more in diameter. There are, in the pictures shown here, some which indicate a tendency toward doubleness which gives rise to the thought that the new pink daisy, if desirable, might be entirely filled up with petals so that its center would not show at all, even as its very distant relative, the old maid's marigold, has been filled up-an interesting process which will be explained later. Those daisies with the tendency toward darkened petals at the inner end might be cultivated and selected until finally they produced an offspring of a purplish black in the center with only a fringe of color, or, until the whole inside was solid black. In other of the variations which are shown, it might be noted that some are pink, or yellow, or of colors in between, inside and out, while others show deep red or purple streaks on the backs of their petals. From these it might reasonably be expected to produce a daisy having one color within, and another color without. From the bed of seedlings pictured, with no two daisies exactly alike, there might be prepared a list of a thousand different tendencies, each susceptible of cultivation, each the possible starting point of some new transformation. It is only when the life history of a plant, with all of its divergent tendencies, is uncovered in some such way as this, that the plant architect can see the full possibilities of further improvement.
The pink daisy which Mr. Burbank grew especially for the purpose of illustrating this chapter may, or may not, be a desirable production-it may or may not repay the thought and effort which it cost-but it shows the simplest method which the plant architect has within his reach-a method which, applied in the same way toward the accomplishment of a more utilitarian purpose, has meant and will, more and more, continue to mean, untold fortunes of added wealth to the world.
In order that the illustration may be complete, let us sketch some of the possibilities of employing this method. Let us begin with some garden vegetable which for centuries has been picking up traits along the lines in which we have encouraged it-working away, always, from the wild, and toward the accomplishment of our ideals. Let us say that we have been selecting it, unconsciously perhaps, for its tenderness, or sweetness, or early ripening, or productivity, or along any line which has made it more desirable or more marketable. Its evolution, then, has been simply a slow response to a new environment which for the first time in its history included man. Suppose, now, that we desire to work, in a single season or a dozen seasons, an improvement in this vegetable which will overshadow all of the improvement which countless generations of cultivation and unconscious selection have wrought. Our first step is to secure its wild counterpart-inedible, maybe, sour, perhaps, tough, no doubt; wholly undesirable as compared with the plant which the seed bought at any grocery store will produce. Nevertheless in the wild brother of our plant there is confined an infinity of old heredity just-is an infinity of old heredity was confined in those two daisies; and the bees, and the winds, can bring forth variation between the tame and the wild, just as striking and just as widely divergent as the variations in the daisies. Perhaps the first attempt to mix up the heredities of the tame and the wild might produce no improvement--only retrogression. But if we keep on mixing heredities and combining combinations of them, we shall soon see before us evidences of all of the tendencies of the plant-tendencies which, though perhaps not desirable, point the way to an end worthy of accomplishment. Then, instead of working with a single wild and a single cultivated plant, if we seek out a dozen wild plants or a hundred of them-some plants from mountain environments and some from swamps, some from rich woodland soil, and some from the desert, we shall get a still better idea of the possibilities stored within the plant-possibilities which need only combination and selection to bring forth a perfected product.
Or, suppose we have a tree which bears delicious fruit in small quantities. Let us then find one with a tendency to over-produce, even though its fruit, in size, flavor and appearance, be inferior. In some combination between the two, simply by following the leads which those combinations themselves will give, we shall in a few years, very likely, discover one variation which combines the productiveness of one strain of heredity with the deliciousness of another.
Or, perhaps, we have a plant which bears us berries of wonderful flavor, but too small to be marketable. Let us find a plant with large, beautiful berries, even though they be insipid, and see if, between the two, by matching heredities, there is not to be found some new berry which is luscious, large and beautiful.
Or, supposing that in our own particular soil there are varieties we should like to grow which fail to prosper, while other less desirable varieties do well. Our problem then is but the combination of heredities to bring the desirability of one with the hardiness of another into a single new plant which, as it were, we make to order.
Or, if there is a variety which will not withstand the rigor of our winters, perhaps it can be combined with a poorer variety which has been educated to them. Or, the other way around, if there is a plant which withers in the heat of our summers, perhaps some combination can be effected with an already existing brother or cousin, which, throughout the generations, has conquered the obstacle of heat.
And so on throughout the whole world-wide range of environment. We shall find plants which have grown accustomed to the wet, and plants which are hardened to the dry; plants which thrive in heat and plants which thrive in cold; plants which like sandy soil, and plants which can do well even in adobe clay; plants which have become used to the glare of the sun, and those which live retiring lives in the deepest recesses of the shade; plants which bear flowers large and small, early and late, of short seasons and of long, fragrant and unscented, simple and complex. We shall find fruit-flavors which are sour, sweet, acid, bitter; fruit skins which are smooth, fuzzy; fruits themselves that are large, small, even, irregular, coarse, delicate; we shall find those which will stand shipment across a continent and those which spoil almost as soon as they are picked. We shall find a range of differences in wild plants, as great as the range of environments in which they have grown. And we shall find a range of differences in cultivated plants as great as the range of differences in races and nations and individuals who have grown them.
"I saw an interesting illustration on the relation between heredity and environment at the circus one day," said Mr. Burbank. "There, in a wire cage, was a tiny dog together with a lot of monkeys. While I was watching, a trainer appeared and snapped his whip. The monkeys quit their play with the dog, ran around in a circle, and climbed up the wire of the cage. The little dog followed them, but could not climb. He would start up and drop back, start up again and drop back again. Then he would look down at his feet, and if a dog ever showed surprise, that dog did. He seemed to be wondering why he could not climb as monkeys do. The environment was there, but the heredity was different. We see the same thing in plant life. The sweet peas with their tendrils and the nasturtiums with their leaves can climb like the monkeys, while other plants can not be forced to climb because there is no climbing heredity within them. You may try to make corn climb a hop pole, or to make hops grow straight in the air without a pole or string. But in a lifetime you can not succeed. It is heredity, heredity, heredity. Environment, unless oft-repeated, only serves to bring heredity out. The climbing monkeys and the disappointed dog show us an important truth in our work. If we want to take advantage of a climbing tendency in a plant or an animal, let us by all means find a plant or an animal in whose heredity that climbing tendency is a part. Let us not try to teach monkeys to bark, or dogs to swing from the limbs of trees by their tails; let us not try to make corn climb the hop pole, or to transform hops into shade trees. Maybe these things could be done. In fact, with unlimited time, there is no question that they could be done. But with plenty of plants about us with ready-made heredities of which we can avail ourselves in a single season, it would be folly to try to accomplish the same result in a harder way, well knowing that only the twentieth or thirtieth generation ahead of us could see the results of our work. In our search for heredities we shall find many plants which are scarcely worth working with-plants whose environments have not led into heredities which are desirable for our ends. But at the same time we shall find scores and scores of plants in the least expected places-plants like the cactus, which, at first, seem impossible of use-which with a little encouragement yield us rare heredities for our work."
When the masons, and carpenters, and decorators have finished the architect's house, and the keys are turned over to the new owner-then, and from that moment, the structure begins to depreciate until it crumbles in decay. The furniture movers dent the stair rails, the children scratch the doors, dust begins to darken and destroy the lustre of polished surfaces; and the sun and night, and the frosts and the thaws, and the rain and the heat, slowly and irresistibly carry the structure on its downward grade. But when the architect of plants has combined old traits into the production of his ideal, he has fashioned something which, if his work is well done, the suns, and the rains, and the frosts, and the winds will not depreciate; he has produced a living thing which, in spite of discouragements, and neglect, and abuse, will keep on, and on, and on-improving as it goes.
How few, indeed, are the materials which the architect of buildings has at his command, when compared with the range of living traits which the architect of plants may call into play!
-Our search, then, is a search for stored up heredities-a search for living traits.
This text is from: Luther Burbank: his methods and discoveries and their practical application. Volume 1 Chapter 5