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DESIGNING A STRAWBERRY TO BEAR THE YEAR AROUND

AND OTHER WORK WITH STRAWBERRIES

A plant enthusiast was explaining the functions of plant life one day to that most appreciative and stimulative of all audiences, a company of school children. He had told of the supreme importance of the seed-how Nature must first and foremost think of that, because it is the link between successive generations of plants; the only means of assuring a continuance of the race. To bring the illustration home, he had said that the seed is the very heart of the plant. A little miss who had absorbed every word with the eager receptivity of the child mind looked up quickly as he finished and said: "Then the strawberry is a plant that wears its heart on its sleeve, isn't it?" It is only the imagination of children-or of the chance individual here and there who remains a child all his life and whom therefore we term a poet-that can sound the depths of a great subject with a single phrase like that. "The plant with its heart on its sleeve." That is the strawberry. Cowering, timid, nestling among the grasses, seeking obscure corners, retiring as far as it may from observation-and wearing its heart on its sleeve! The strawberry, it must be recalled, is own cousin to the peach and plum, the apple and pear, the rose, the blackberry, and the raspberry. But where these raise their heads into the air and hold out their flowers and fruit to the inspection of all the world, the strawberry has taken to earth and become a creeper. Yet whereas the other fruits shield their seed always with pulp of the fruit, and some of them even enclose it also in armor plate shells, the strawberry puts its seed on the very outside of the fruit, where they will inevitably be eaten by any bird that so much as pecks at the fruit itself, hence the pertinency of the little girl's characterization.

THE ODD CUSTOM EXPLAINED

But, of course, there must be an adequate reason for the curious conduct of the strawberry. A plant does not depart from the traditions of its ancestors and take on new and strange customs unless it finds advantage in so doing. The case of the strawberry is no exception. That this plant is admirably adapted to its environment, and for that matter to environments of great diversity, is shown by the fact that strawberries of one species or another grow in regions as widely separated as Patagonia and Norway and Alaska. And that the anomalous character of its fruit has very distinct advantages is evidenced by the fact that in all the diversified regions in which it grows the strawberry holds to precisely the same architectural scheme in the building of its fruit. The leaves and stems and manner of growth of the different species may vary considerably, although even here there is no very wide diversity. But as to fruit, every strawberry of whatever species may be instantly recognized as a strawberry by the most casual observer. You may never have seen the species before but you could not possibly mistake the fruit for the fruit of any other tribe of plants. A pulpy berry with tiny seeds sprinkled over it and only half imbedded in the pulp, like seed on the frosting of a cake, is a strawberry and nothing else. Almost every other fruit has counterparts that suggest close relationship. Peaches and nectarines, apricots and plums, apples and quinces, oranges and grape fruit, lemons and limes, blackberries and raspberries, watermelons and muskmelons-these and sundry other fruits seem to go in pairs, as it were. They show the result of Nature's constant tendency to experiment and to find new ways of doing the same thing, each method reasonably well-adapted to its purpose. But when the scheme of the strawberry had been perfected, it would seem that it must have proved so very admirable that there was little chance to improve upon it and no occasion to vary from it. Hence strawberries are quite in a class by themselves from the botanical standpoint, just as they are from the gastronomic standpoint. In admitting this, it does not follow that we must agree with the enthusiast who declared, not long ago, that the strawberry is the one fruit that is past all improvement. We shall urge in a moment that there is still a good deal to do before the strawberry can be considered a really perfect fruit from the standpoint of the consumer. It can be made, and should be made, to give up its seeds altogether, for example. Now that it has come under man's protection, it does not need the seeds, any more than the pineapple and the banana need them. Aforetime it placed the seeds on the very outside, where they would necessarily be eaten by any bird or animal that tasted the fruit, because it was imperative that the seeds should find means of transportation in order that the race of strawberries might spread and inhabit the earth. The plant that cowers close to the ground cannot depend in the least degree on the wind or any other inanimate agency to transport its seeds. It must look to birds and animals to aid in this direction. So the strawberry sprinkled its seeds on the outside of the fruit, having first taken the precaution to cover the inconspicuous seeds themselves with an altogether indigestible shell of cellulose. The subterfuge served the little plant extremely well, as its wide range of wanderings and secure foothold in diverse soils and varied climates sufficiently attests.

THE SEEDS NO LONGER NEEDED

But now, as was said, this expedient is no longer necessary. Men will take good pains to see that the strawberry is abundantly propagated. And as such propagation may most advantageously be made through the agency of roots and runners rather than with the seed, there is no longer any necessity whatever that the seed should be retained. There are a good many scores of them on a single fruit; and the draft on the energies of the plant required to produce this large quantity of concentrated germinal matter must be very marked. So when the strawberry has been induced to give up the seed-producing habit altogether, devoting its fruiting energy to the production of the juicy pulp of its unique product, the plant itself will advantage by the change, while at the same time gaining added favor with the fruit lover. Not a great deal has hitherto been done toward relieving the strawberry of its seeds, because hitherto the plant developer has been concerned to increase the fruit itself and has given small thought to the seeds or has ignored them altogether. But the briefest inspection of different strawberries will show that they differ a good deal as to relative abundance of seed; and there is no reason to doubt that the plant developer who undertakes this selective breeding with an eye to the preservation of plants that show a tendency to minimize the seed product, will gradually develop a race of seedless strawberries. It appears to be quite the rule that plants habitually propagated by root division or by rooting stalks or runners tend to lose their power of seed production when long cultivated. The pineapple, the banana, the sugar cane, the horseradish, and the potato, have been previously referred to in this connection. All of these, as is well known, are regularly propagated by the cultivator without the use of seed, and it is only under the most unusual conditions that any one of them nowadays produces seed at all. I took occasion to emphasize this fact once in a lecture or an interview by saying that I would very willingly pay a thousand dollars an ounce for horseradish seed. The joke went the rounds of the papers and hundreds of people all over the country watched their horseradish plants the ensuing season with an idea to gaining the prize. Needless to say no one has yet produced the ounce of seeds, or any fraction thereof. Of course there are certain disadvantages that will attend the entire giving up of the habit of seed production. It is not that the plant propagated exclusively from the roots or cuttings degenerates, as was once thought to be the case. In reality there seems to be no limit to the number of generations through which a plant thus propagated by division may maintain its original standards of quality. The familiar cases of the orchard fruits sufficiently support this belief. It may even be possible to improve a plant slightly by selection when propagated solely in this way. But, on the other hand, it is obvious that the plant that gives up the habit of seed production renounces the possibility of benefiting by the introduction of new strains through hybridizing-a process, as we have all along seen, that is the principal means through which plant evolution is brought about. So, as regards the strawberry, it will be desirable to make sure that we have developed a fruit to approximate perfection before we induce it to give up the habit of seed production altogether. It can hardly be claimed that the strawberry has reached this stage of development, notwithstanding the verdict of the enthusiast already quoted. But, on the other hand, it must be admitted that the best varieties of fruit approach an ideal standard rather closely. And when we recall that the development of these almost perfect varieties has taken place very rapidly and within comparatively recent times, it seems a fair conclusion that it will be possible to complete the perfection of the fruit in other directions in less time than it will take to remove the seeds. So the plant experimenter who would undertake the task of eliminating the seeds from the strawberry need not hesitate for fear of succeeding too soon. Unless Nature should produce a chance sport that is without seeds, or nearly so, somewhat like the nearly stoneless plum, the task of removing the seeds of the strawberry by mere selection would prove an arduous one. Yet, as I said, it can doubtless be accomplished; and the game is thoroughly worth the candle.

ORIGIN OF THE CULTIVATED STRAWBERRY

Partly because all strawberries are so much alike, it has been unusually difficult to trace the origin of this fruit. But it is known that the modern varieties have been developed in a period of not more than two centuries. The strawberry has indeed been under cultivation for an indefinite period. But the ancients were doubtless content, as we know that the moderns were until a few generations ago, with a small berry scarcely superior to the ones that grow wild in many regions of America. The systematic cultivation of the fruit began in England after new species of strawberry were introduced from North and South America. But the really notable progress did not take place until the South American species known as Fragaria Chiloensis was introduced early in the eighteenth century from Chili. Nor indeed was there any immediate improvement from the introduction of this fruit. But about the year 1760 a new variety suddenly appeared that was called the Pine strawberry because its fragrance suggested that of the pineapple. There was no record as to its origin, but the best authorities argue with good reason that it was a hybrid between the Chilian strawberry and the American species introduced much earlier from Virginia. As usually happens when different species are hybridized, a tendency to variation was produced, and before the close of the eighteenth century there were two important types of new strawberry of the Pine variety, one of which was named by the botanist Fragaria ananassa and the other Fragaria grandiflora. It is argued with plausibility that these are modified forms of the South American strawberry introduced from Chili, the precise share of other species in the combination not being perhaps clearly established. The most popular modern varieties of strawberries are the descendants of this so-called Pine stock, the most notable impulse to the development of new varieties having been given through the introduction of Keen's seedling in England in 1821 and Hovey's seedling in America in 1837. Subsequent development has come about through the usual method of crossing and selecttion. Of curse, many varieties, differing in such minor details as the production of runners, resistance to fungus attacks, and precise qualities of the fruit have been developed. Different races also show a diversity as to manner of flowering, certain varieties bearing pistillate flowers, just as the California dewberry does, whereas others bear perfect or bi-sexual flowers, as is customary with the members of the rose family in general. But these are minor differences; and, as we have seen, the strawberry type in all its essentials has been marvelously maintained from first to last. Now as always this fruit is unique and curiously isolated.

HYBRIDIZING EXPERIMENTS

My own experiments with the strawberry have been carried out on a rather expansive scale, although I have given by no means as much attention to this fruit as to a good many others. I have crossed all the familiar cultivated varieties, and in addition have made hybridizing experiments in which numerous wild species, some of them imported from distant regions, have had a share. I have, for example, commingled the strains of the best varieties of the cultivated strawberry with those of strawberries from Norway and from Alaska, and the native Chilian species, as well as with various wild species of our own. I have also attempted to hybridize a species from India, the Fragaria Indica, with other strawberries, but have been unsuccessful. It does not by any means follow that this cross cannot be effected. But it is perhaps not worth while to devote an undue amount of time to the experiment as the qualities of the Indian species are not such as make it certain a hybrid thus produced would have any value, except possibly as introducing a tendency to variation. The Indian plant bears a small, insipid berry, and is cultivated for ornamental purposes only. There are various wild strawberries growing along the Pacific Coast that offer interesting possibilities of hybridization. It is rather interesting to know that some of these are of the same type with the Chilian species that has already been named as the chief progenitor of the cultivated strawberry. One of these, known as the sand strawberry, is quite common along the coast, especially in the northern part of California. This is a plant with large, woolly leaves. It is greatly inclined to produce runners. It fruits sparingly, but the berries themselves are sweet and of fine flavor. There is great variation as to foliage and flowers, as well as in capacity for fruit production. The variation is best explained by assuming that this strawberry is itself a natural hybrid. Another California strawberry that has interest is the wood strawberry, Fragaria Californica, a plant that usually has small leaves, rather upright in growth, and producing fruit abundantly, though the fruit itself is insipid and hardly worth gathering. This plant also varies widely in different localities. In the Yosemite Valley I found a most astonishing variation in these as well as in other strawberries. Some of the wild varieties growing there were fully equal to the cultivated strawberry, while others were insignificant to the last degree. Some of the plants grew strictly upright; others had leaves that hugged the ground and spread in all directions. There was a wide range of variation as to form, size, foliage and fruit. This was quite the most interesting group of strawberries that I have come across anywhere. But these plants do not seem to thrive in the valleys as they do in their mountain home. As to the latter point, I have noticed a striking propensity on the part of certain strawberries to degenerate when placed under changed conditions of soil and climate. We have seen that plums and many other plants are stimulated to exceptional growth by precisely such a change. But when the promising wildlings from the Yosemite were transplanted to my gardens they ran to vines and produced very little fruit, although in their native habitat they had borne abundantly. The experience was precisely the same with certain strawberries that were sent from Alaska, and from Norway, and in many of those from Chili. When the Alaskan vines came to me, they were fruited and they revealed an abundance of splendid berries. But under cultivation in my gardens they failed to thrive and such fruit as they produced was of inferior quality. The new soil and climate, which had proved such a stimulus to Japanese plums and New Zealand rhubarb and European daisies, and almost countless others, proved a handicap to the Alaskan strawberries. The new environment was not adapted to their constitution. I have sometimes had the same experience with other plants, including certain varieties of currants, blueberries, huckleberries, and raspberries, as well as maples, beeches, hickories, and other trees from the eastern United States.

NEW HYBRID VARIETIES

But, of course, there are many other species and varieties that have shown no such antipathy to the conditions it had to offer, and I have produced large numbers of crossbreed strawberries from various importations that have prospered. In the course of the past forty years I have probably grown and fruited strawberry seedlings to the number of more than half a million; and among these have appeared some varieties that have had qualities of a high order, yet among them all I have not until somewhat recently secured one that was thought in all respects superior to some existing variety. Therefore, none of these were introduced. Ten or twelve years ago I had one that was nearly perfect but which proved to be a poor keeper and therefore not suitable for the market. But more recently, as the strawberry strains became blended, a variety was produced which not only excels in quality but has the highly desirable characteristic of persistent bearing. The new strawberry has been developed through hybridizing stock that had among its ancestors such well known varieties as Longworth's prolific, Brandywine, Monarch, and the Arizona Everbearing, and one or two varieties from Texas. The later hybridizations, through which the perfected strawberry was finally secured, have involved crossing the Chilian strawberry with the white strawberry from Virgina and with the wild Pacific Coast strawberry. From these two lines of hybrids I have obtained the only seedlings that have been thought worthy of introduction. The paragon of these is a plant of vigorous growth which makes just the right number of runners, and which has a healthy, thick, dark green foliage. The fruit is borne in clusters well up from the ground, and is delicious in quality, I confidently believe, beyond any strawberry before known. This has been the universal verdict of those who have tasted the fruit of this complex hybrid. When John Burrows visited my garden, for example, he unhesitatingly pronounced this strawberry the finest in the world. So great was his enthusiasm that he wrote to eastern seedsmen, advising them to secure this strawberry, as everyone would soon be wanting it. The fruit of this hybrid is not extraordinarily large, but it is firm in texture, of a fine crimson, and unlike most other strawberries it has a yellow flesh. Its lusciousness and deliciousness of flavor will give it a place apart even among the most select varieties of the fruit. But quality of the fruit is not the only merit of the new hybrid. The plant has also, as just intimated, the singular and important quality of bearing fruit throughout the summer. The main crop comes at the usual time for strawberry ripening, but berries continue to ripen, even if less profusely, month after month. Doubtless this habit of perpetual bearing is a trait brought out by the mingling of so many racial strains; in particular by the union of races from the two hemispheres. The summer of Chili is of course our winter. I have several times adverted to the confusion that seems to overtake many plants when brought to our northern latitudes from the southern hemisphere. The case of some of the New Zealand apples, which were confused as to time of bearing for two or three years after being imported, will be recalled. Also the case of the winter rhubarb, which came to be a perpetual bearer partly through the influence of such transplantation. The new hybrid strawberry, which combines ancestral strains from the two hemispheres, furnishes another illustration of the tendency to retain ancestral habits as to time of fruiting, and thus, where parents from both hemispheres are involved, to develop among some of their seedlings a new habit of perpetual bearing. It will probably be possible, by further selection from the new race of all-the-summer bearing strawberries, to extend their time of fruiting, as was done with the winter rhubarb, until they bear throughout the year in any climate where the winters are sufficiently mild.

NEW VARIETIES IN THE MAKING

Other novelties that have developed among the progeny of the company of widely hybridized strawberries include constant producers and enormous producers that as yet lack some other quality which will presently be supplied. I have also a white strawberry, grown from a variety that I grew in my childhood back in Massachusetts, and which was said to have come from Virginia. By hybridizing this species a few promising white strawberries have been produced with new and delicious flavors. These are not yet quite as productive as could be wished. But second generation seedlings in great numbers are being raised, and interesting results are sure to be attained in the near future. My strawberry stock, like my stock of plums and some other fruits, now consists of complex hybrids from which almost anything may be expected. At least it is certain that new combinations of qualities, within the extreme range of strawberry variation, will appear among the seedlings of these conglomerate yet carefully nurtured and selected stocks. Summarizing my work on this fruit, I would say that selections have been made almost altogether for flavor rather than for size and color. I thought that a good home strawberry that is tender, sweet, and of fair size rather than of exaggerated proportions, combining these qualities with the exquisite flavor of some of the wild berries, would be a distinct acquisition. The varieties already in the market were many of them of enormous size, but for the most part they lacked flavor. Anyone who has known the small wild strawberry at its best must always experience a certain disappointment in eating the cultivated varieties. Moreover, most of our market strawberries are hard, being judged by the growers and the dealers by their shipping quality rather than by their flavor. It seemed desirable, particularly for home use, to develop the strawberry for its appeal to the palate as well as to the eye; in other words, to restore to the fruit something of its pristine flavor, while retaining the good qualities introduced in recent times by selective breeding. Such an endeavor to improve the flavor of the fruit, combined with the idea of all-the-year bearing and ultimately of seedlessness, may be said to suggest the lines of improvement along which the plant developer of the immediate future should work in perfecting the strawberry. But the production of the seedless strawberry, as already pointed out, must be the final stage of the process of development. When the seeds are gone, there will obviously be no further opportunity for improvement by selective breeding, with or without hybridization. But long before the seeds are bred out, we shall doubtless have many varieties of strawberries that approach perfection as to all other desirable qualities.

-Nature has done much for the luscious strawberry, but there is still as much or more for us to do.

This text is from: Luther Burbank: his methods and discoveries and their practical application. Volume 6 Chapter 3