Volume Number: 1  2  3  4  5  6  7  8  9  10  11  12 




If you are disposed to undertake a series of practical experiments along the lines suggested in the preceding chapter, it is by no means necessary for you to send to distant countries for the material. Of course, the professional plant developer is always on the lookout for plants from China and New Zealand and such far-away places. But the amateur need not be deterred by the difficulty of securing such materials. It suffices perfectly for him to go into his garden and begin his experiments with the first flower he chances to find there. Any old-fashioned flower garden, such as adorns the door-yards of millions of homes in America, will furnish abundant material for all the experiments that any amateur need care to undertake. Let me name almost at random a few of the common garden flowers that offer interesting opportunities for development, and any one of which will serve quite as well as another for the commencement of your tests of the possibilities of plant development. Take, for example, the familiar iris, known sometimes as the rainbow plant. There are specimens of it, in one variety or another, growing in every garden. It makes its way if given the slightest opportunity, and its somewhat lily-like flower with the graceful recurved fringed petals has retained its popularity generation after generation, notwithstanding the coming of many new favorites. My own work with the iris has had to do largely with a Japanese species known as Iris laevigata. On an acre of damp ground that I have at Sebastopol, I raised great quantities of these flowers a few years ago. The combination of colors was beautiful beyond description, varying in all shades of the rainbow. Among the seedlings were numbers that produced double flowers, and sometimes the double ones took on handsome and unusual shapes, in other cases the anomalies of form were grotesque and even monstrous, rather than beautiful. Some of the seedlings produced almost ten times as many flowers as others, the individual blossoms being of equal size. Some were tall and lanky and could hardly support themselves when in bloom. Others were short and compact. The range of variation was from dwarfed forms of eight inches to giants of four feet or more. And that the variation was due to heredity and not to any environmental conditions was shown by the fact that the dwarfs and giants might stand side by side in the same soil and subject to precisely the same conditions of moisture. There was not much demand at that time for new varieties, so I ultimately sold the entire lot of hybrid Japanese iris as a mixture, without names or numbers, not taking the time to sort out and fix different types by selective breeding. In addition to the Japanese form, I have raised a great number of other species, including one interesting form in which the seed pods turned out in a curious way and exposed the orange or scarlet seeds. This is a species known as Iris foetssissima. I grew this anomalous form extensively to produce a race that would have seed pods and seeds that would have better form and open more fully. It is not necessary to go into details as to the score or more of other species that I have grown, as they all reveal more or less similar tendencies to variation, and suggest over and over the same possibilities of development. It does not matter very much, then, what particular variety of iris is growing in your garden. Probably there are plants that bear purple flowers, others with yellow ones, and yet others that are white. This obviously gives you opportunity for hybridizing, and there will be abundant interest in watching the results of the blending of different colors. If at the same time that you are crossing the iris of different colors you save also seed from other plants, or from different flowers on the same plants, that are not crossed, you will be able to check the results of your experiment, and will find yourself launched at once into an investigation that offers fascinating possibilities. It should be explained, however, that the cross-pollenizing of the iris presents complications which will not be solved unless you make a very careful inspection of the flower. The stigma of the flower has a little lip under the unique petaloid pistils, very different in appearance from the organs of most other flowers. If you examine it closely you willl see that the little shell-like lip that projects is adjusted in just the right way to scrape pollen off the back of a bee as it enters the flower, or similarly from the head of a humming-bird. The arrangement is such that the bee or humming-bird will come in contact with the pollen of an individual flower only after it has passed the pistil, and the protecting sheath prevents the deposit of pollen as the insect or bird leaves the flower. Thus it is insured that self-fertilization will not take place. While the flower is, as I said, complex in this regard, nothing more is necessary than to study its mechanism attentively, pulling to pieces two or three blossoms to see just how the pollen must be deposited. After that you will experience no difficulty in cross-fertilizing the iris, and the results of your work are sure to be of interest.


The familiar four-o'clocks are all natives of America, but most of them had their original home in the sub-tropical and tropical portions of our continent. There is one, however, that is native to California, and various species made their way to the gardens even far to the north a century or more ago, and are now grown everywhere. The most striking peculiarity of the four-o'clocks is their tendency to combine different colors in the same flower in peculiar patterns. We have seen a great deal of color variation among flowers. We have seen numberless instances in which blossoms of the same species may be in one case red, in another pink, in a third yellow, and in a fourth white. We have seen also some instances of the mingling of different colors in the same flower, notably with some of the dahlias. But our attention has been called to no flower that mingles the colors in quite so anomalous a way as is characteristic with the four-o'clocks. For these blossoms, seemingly unable to decide between different colors, have hit upon a compromise of arranging the colors in definite stripes, which give the tubular corollas a very curious and characteristic appearance. In a lot of seedlings, supposedly of the same variety, the stripes may come in various widths of white, crimson, and yellow. Even when the seed is saved from a single plant, there will be great variation among the seedlings, in some the wide white stripes predominating, in others the crimson, and in yet others the yellow. Again, some of the flowers may come pure white, or yellow, or crimson, or pink, quite without stripes; or perhaps half of the blossoms on a given plant will be one color and half another. It is obvious that a plant showing such wide variation does not call for hybridization to stimulate variation. The mingling of hereditary strains is already sufficiently complex, and you will find quite sufficient occupation in attempting to sort out new races of a good color or combination of colors, and in fixing a dozen of them so that they will come reasonably true to type. If you succeed in accomplishing this, in the course of a few seasons, you will have performed an experiment that you will find full of interest, and your task will not have been carried out without giving you very suggestive sidelights on the problem of heredity. It is, in any event, a very curious anomaly that a plant should so have assorted its hereditary factors that they adopt this compromise. And your investigation, which endeavors to determine how accurately the tendency to striping is dependent on particular combinations of hereditary factors, will not only prove interesting, but may lead to valuable revelations. The entire problem of the study of heredity of color, notwithstanding the attention that has been given it, still bristles with unanswered questions. Your experiments with the old-fashioned four-o'clock may serve to give you answers to some of them. A somewhat simpler but perhaps no less interesting problem in color heredity may be taken up in connection with the equally familiar columbine. There are thirty or more species of the genus Aquilegia, or tribe of columbine, and examples of one or two of the more common ones are sure to be found in your garden. At least you can get seeds from which to grow them at any florist's. I have always been fond of the columbines because of their numerous species, and their wide range of color variation; also because of the curious shape of the flower and the tendency of the spurs to vary greatly in length, as well as in their tendency to open out in some cases, and in others to remain partially closed. There is, indeed, one old cultivated variety which has lost the spurs altogether. I made at one time some interesting experiments with this spurless kind of columbine, crossing it with many others, especially with one known as the coerulea, which has very large flowers of beautiful shades of blue. The hybrids of this spurless form with the other species produced beautiful large climatis-like flowers, some of them three or four inches in diameter. Perhaps the most interesting feature of the experiment was that the hybrids were entirely spurless. This shows that the condition of spurlessness, which is an anomaly presumably of recent origin, inasmuch as the spurs are a characteristic feature of the flowers of the wild columbines, acts as a dominant factor in heredity. This, of course, is what should be expected if it be true that the newly developed characteristics of a plant are dominant over the older ones. But the case of the columbines furnishes another interesting corroboration of this interpretation of Mendelian heredity. In the course of other experiments with the columbines numerous other species were brought into the combination through successive hybridizations, until my columbine colony carried the strains of more than a dozen recorded species. A most beautiful lot of hybrids resulted. Their various members revealed nearly all the colors of the rainbow. I introduced them to the trade as mixed varieties, as it did not seem to be worth while to fix the different types. On the contrary, the variety of blossoms seemed to be considered an advantage. But, in point of fact, even if it had been desired to fix the new types, it would have proved exceedingly difficult to do so. When you have two or more species of columbine in combination, the hereditary complications are comparable to those in the gourd family, to which we have had occasion to refer. It seems as if every member of a fraternity differs from all other members, and you cannot be at all sure as to what results you may attain by sowing seed from any individual plant. But these complications result in part from the fact that the different columbines are so easily crossed by the bees. This is a case where there is no difficulty in effecting hybridization; the difficulty is to prevent crosses that are not desired. If the plants are shielded from the visits of the bees, and careful hand pollenizing is effected, there is no great difficulty in combining the different forms in such a way as to get definite results, and the hybrid forms may be fixed by careful selective breeding. Of course, when you deal with a spurless form, if the individuals that you use are themselves hybrids of the first generation of a cross between a spurred and a spurless variety, their progeny, when they are crossed with a spurred variety, will be in effect second generation hybrids and only half of them will be spurless. But this, again, merely illustrates the familiar segregation of characters and the reappearance of the recessive trait -in this case the spurred condition-in a rather definite proportion of the second generation progeny. Another anomaly among the columbines that offers good opportunity for experimental tests is furnished by the double varieties. I used to notice that if you crossed a double and a single one, you are about as likely to get a double as a single. Here, again, it would appear that the double condition of corolla acts as a Mendelian dominant factor, and that the strains with which I worked were themselves mixed. All in all, then, the columbine offers most interesting possibilities for the experimenter who likes to test for himself the principles of heredity. In the matter of color, there is the widest variation, some of the familiar forms being blue, others red and yellow. The curious spurs that characterize the flower, and the fact that some varieties lack them, furnish tangible features that may be tested, and the single versus the double corolla constitutes a third feature that is also susceptible to definite observation and record. So the experimenter who will work with a small number, differing as to characteristics of color and spur and doubleness, has opportunity for watching the interplay of hereditary forces; observing the dominance of certain hereditary factors, and the recessiveness of their opposing factors; and finally the segregation of the different characters and their reassembling in new combinations in the second generation, that will test his knowledge of the principles of heredity to the utmost, and at the same time will give him definite ideas about the practicalities of plant development that will be at once interesting and valuable. Meantime the experimenter may introduce problems of far greater complexity if he so desires by mixing larger numbers of the plants somewhat at random, and allowing them to be cross-fertilized by the bees. In this way he may secure, as I have done in some experiments, columbines of the most wonderful variety. In some of the mixed hybrid colonies, the blending of hereditary factors was so complex that among ten thousand plants there would be perhaps not five hundred that could be classified as approximately identical with one another, or as conforming to a specific type. In other words, there would be perhaps nine thousand five hundred individual plants, each of which might be said to constitute a distinct variety. In the course of these experiments I made perhaps ten thousand careful hand pollenations between different specimens of these variant hybrids, and, needless to say, secured plants with exceptional blossoms of many kinds. A similar line of experiment is open to anyone who has the smallest plot of ground in which he can grow a few scores of columbines.


If you were to seek experiments of a still simpler character, you might do well to consider the beautiful campanula, known familiarly as the bluebells of Scotland. These are hardy flowers, growing wild in great profusion, even far to the north. On a trip to Canada a good many years ago I was delighted to see great fields of companula as far north as Alberta. They are said to grow even in Siberia. So whatever the location of your garden, you will probably have no difficulty in raising bluebells. The plants, to be sure, are somewhat subject to the attacks of fungus pests and insects, but aside from this difficulty they are easily grown. It goes without saying that a flower that has become famous as the "bluebell" is generally blue in color. Yet it is by no means unusual to see specimens that are pure white. And it is this variation that gives opportunity for some simple experiments in cross-breeding. Nothing more is needed than to secure plants of the ordinary blue variety and others that bear white blossoms. The campanulas are easily crossed, and you will have opportunity to test the color variation in heredity in some of their simplest relations. There are, to be sure, many species of campanulas, and it is true that the garden varieties are likely to have been hybridized. I have, for example, raised seedlings from the white campanula, Rotundiflora, without securing any white ones. It will be necessary, therefore, for you to test your varieties by raising plants of uncrossed seeds at the same time that you are making the cross-pollenations. But this complication will only add interest to the experiment. The many tribes of coreopsis give opportunity for experiments of equal interest. These plants are cornposites, and in hybridizing them it will be necessary to use the method detailed in our story of the dahlia, washing away the pollen before applying pollen from the other flower. The different members of the family vary in color from deepest purplish crimson to light yellow and white. There are numerous species under cultivation, and there are wild ones growing as roadside weeds that are readily accessible. The variability of the different races makes them an interesting race with which to work. My own work with the tribe has included a good many species, the most important of which is the one known as the Coreopsis linceolita. The experiments look to the increase of the number of florets, as well as to the size of the flowers and abundant bearing. I also had in mind improving the form of the plant. There was no great difficulty in doubling the size of the flower, and in the course of four years, working with seed purchased in the common market, varieties were produced that were considered worthy of introduction, and that were distributed by several leading florists. The developed varieties had exceptional value because of the large size of the flowers and of the small center; also because of the long stems, making it a good flower for cutting. A fault of many of the annual varieties is that they have small, weak stems. As to all of these matters, the amateur can work by selection and by hybridizing. The wide range of color variation affords a ready guide in hybridizing experiments, and the ease and certainty with which the plants can be grown from seed adds greatly to their utility from the standpoint of the amateur.


A really fine plant that offers opportunity for improvement, yet which has been little worked with, is the Shooting Star, sometimes called American cowslip, a member of the primrose family, classified under the genus Dodecatheon. There are sixteen or eighteen species described in botanical literature, yet so great an authority as Asa Gray thought that all the Dodecatheons in the world should be classified as one species. There are remarkable variations in size and color, however, yet the varieties are sufficiently fixed to offer good opportunity for experiment, and at the same time are closely enough related to that they may readily be crossed. The flowers of the various types show the widest variation-dark purple, crimson, rose, white, spotted, cream color, and yellow. There is opportunity for sorting out individual colors and their fixing through selection; and, on the other hand, for the combination of colors to produce new shades. The plants are handsome, and they furnish admirable material with which to work, not merely by way of gaining experience, but also with the possibility of producing worthy new varieties. The Salvia are members of the mint family. There are many species, showing a wide range of variation. The commonest one is known in every garden for its brilliant red flowers borne in such profusion as to make splendid masses to group along walls or as borders. There are other salvias, however, that have charming light blue flowers. The plant in the ordinary gardens is grown of course, only for its flowers, yet there is a species, known as Salvia sonomensis, or Salvia ramona, that is abundant on some of the hillsides in California, and that is to all intents and purposes identical with the cultivated sage. Its foliage has the exact flavor of that of the cultivated plant. I have at times thought of growing it to see if there could not be developed from it a sage that would be more valuable for seasoning than the one under cultivation. The common sage runs into numerous varieties, some woolly leafed, some golden leafed, and some with tri-colored leaves. It is possible that by hybridizing this plant with the wild variety improvement would be made in the unique quality for which its leaves are prized. From the present standpoint, of course, our interest in the salvias concerns their flowers. I have done a great deal of work with various members of the family, both in the way of selection and of hybridization. The plant is tremendously variable, even within the same species, and the various forms run more or less together so that it is difficult differentiating them botanically. But the contrast between the species bearing blue flowers and the familiar garden plant with its scarlet blossoms is striking enough to challenge the attention even of the least observant. The fact that the various species can readily be hybridized, while at the same time they show such variation as to color of blossom, gives them obvious interest from the standpoint of the amateur plant experimenter. It should be noted, also, that there are some salvias with white leaves, one of these having foliage so thoroughly covered with a white thick wool-like growth that the leaves make excellent pen wipers. The experimenter who works with one of these varieties could doubtless develop interesting modifications of leaf through selection alone, and, of course, hybridizing methods could be utilized to accentuate the variation. A plant that is exceptionally interesting because of the work that has been done with it in recent years is the familiar evening primrose (Oenothera). Mention has been made in another place of the famous work of Professor DeVries, which furnishes the foundation for his 'celebrated theory of mutation. It will be recalled that Professor DeVries found specimens of evening primrose that departed so widely from the form of their parent as to seem to constitute new species. The question whether these mutations were of unexplained origin, or whether they were really due to hybridization, is still perhaps an open one. But, in any event, the use made of them by Professor DeVries called particular attention to this plant, and has given it a place quite apart among flowers of field and garden. There are many species of evening primrose, and the tendency to vary among them is marked. Variation, however, does not extend to the flower. There may be all manner of modifications of stem and leaf, but the typical blossoms of the evening primrose are of a pleasing pale lemon yellow.


I have experimented with the primroses, crossing them quite extensively. One form that was received from the mountains of Chile has given some interesting results through selection, in that it now produces blossoms, a single petal of which would cover the entire blossom of any of the larger primroses under cultivation. The flower itself is sometimes six inches or more in diameter. A bed of these plants reminds one of a lot of handkerchiefs spread out on a lawn, as the blossoms are somewhat square with rounded corners. A new crop is produced each morning throughout the entire summer. The plant itself is somewhat trailing, and about two feet to two and one-half feet in diameter. It is a perennial, though it commences to bloom quite early in the season. This large flowered variety has been produced by most rigid selection for size, form, and whiteness and substance of flower, and it far surpasses all other members of the genus in size and beauty. I have hybridized this Chilean race with the common Oenothera acaulis, or Taraxacifolia, and produced a large number of intermediates, from the best of which I have made selection. These hybrids seem to come absolutely true in the second generation, so far as foliage is concerned, being in all cases intermediate between the two species. This is perhaps what would have been expected in a member of this race, in view of the observations of Professor DeVries. The plant seems to have an exceptional propensity to form new types. This, of course, is precisely the characteristic that gives the plant interest from the standpoint of the amateur experimenter. So a plot may very well be set aside in the flower garden for some evening primroses of two or three species. Hybridization will readily be effected by the insects, if the experimenter does not care to take the trouble to hand-pollenize the plants, and the production of some interesting new forms may fairly be counted on. I will name only two other common plants from among the almost numberless ones that might be selected, as offering advantageous material for selection by the amateur experimenter. But these are about the commonest of all, and in some respects among the most beautiful and interesting-the golden rod, and the aster. These plants are almost universally associated when growing wild in the field, and their blossoms form so beautiful a contrast that the two may very well be transplanted to the garden together. I have experimented quite extensively with the goldenrods, and at the same time made a collection of the native asters. And while the twvo plants are so very different, the fact that they blossom together late in the fall and harmonize so beautifully in the landscape, makes it worth while, as I have just suggested, to work on the two in combination. The golden rods are of so many species and so variable that they tax the skill of the botanist. To differentiate between them accurately is a task lying far beyond the skill of most amateurs. But for that matter, it is my observation that the different species hybridize so freely when growing wild that the specific lines are thoroughly broken down. Any botanist who pretends to fix hard and fast lines between the different species of golden rods, and does not take account of the hybrids, which are even more numerous in many localities than the parent forms, will not gain a very adequate idea of the golden rods as they actually grow. Any species of golden rod will serve the purpose of the experimenter. But, of course, it is desirable to have a number of species, and it is obviously worth while to make careful selection in deciding which ones to transplant to your garden. I have spent many days on a few acres of ground, searching among the multitudes of golden rods for the most beautiful individual specimens. From these selected seed was collected, or the roots themselves dug, to furnish the basis for further experiment. Some of the wild forms seem almost perfect, yet when taken under cultivation and carefully selected they prove susceptible of betterment. The hybrids, in my experience, are not as variable as might be expected. But this is no doubt because the plants with which we worked were themselves hybrids. In point of fact, one can seldom be sure, in working with the golden rods, that one is working with pure species. But such complications, of course, give added interest to the work of the plant developer after he has the fundamentals of the method fairly in hand. And I can think of few problems that would be more interesting than to attempt to untangle some of the hereditary complications among the golden rods. The fixing of types by selection; the improving of the best existing ones; and the development of new types by hybridization-these are all methods that offer opportunity for fascinating experiments. Whoever takes the trouble to make friends of the golden rod is not likely to regret his experience.

-Any old-fashioned flower garden will furnish abundant material for all the experiments that any amateur need care to undertake.

This text is from: Luther Burbank: his methods and discoveries and their practical application. Volume 10 Chapter 2