I •<•". V. b Bnrbank Seedling Grapes These seedling grapes, of mixed heritage, are almost as large as plums. They are extremely early and of fine flavor; but they do not ripen evenly, as will be noticed. They have many good gualities to be retained, but several bad ones that must be eliminated through selective breeding. LUTHER BURBANK HIS METHODS AND DISCOVERIES AND THEIR PRACTICAL APPLICATION PREPARED FROM fflS ORIGINAL FIELD NOTES COVERING MORE THAN 100,000 EXPERIMENTS MADE DURING FORTY YEARS DEVOTED TO PLANT IMPROVEMENT WITH THE ASSISTANCE OF The Luther Burbank Society AND ITS ENTIRE MEMBERSHIP UNDER THE EDITORIAL DIRECTION OF John Whitson and Robert John AND Henry Smith Williams, M. D., LL. D. VOLUME VI ILLUSTRATED WITH 105 DIRECT COLOR PHOTOGRAPH PRINTS PRODUCED BY A NEW PROCESS DEVISED AND PERFECTED FOR USE IN THESE VOLUMES NEW YORK AND LONDON LUTHER BURBANK PRESS MCMXIV Copyright, 1914, by The Luther Burbank Society Entered at Stationers* Hall, London All rights reserved Volume VI— By Chapters Foreword Page 3 I The Thornless Blackberry — And Others — Some Transformations in *7 the Bramble Patch II The Raspberry and Some Odd Crosses — Much Betterment — And a OQ Few Baffling Problems «** JTI Designing a Strawberry to Bear the Year Around —And Other Work 70 With Strawberries IV The Sunberry— A Production From the Wild —A New Food Plant From a TAr Poisonous Family V A Dozen Other Delightful Berries —Offering Encouragement to 1 O C Combineand Build 1O° VI Great O Great Opportunities In the Grape —Generations of Grape 1 0 1 Experiments Help Us 1O1 VII The Cactus Pear— A Profitable Fruit —Its Flavors Fixed, Now Working oi q Mostly for Seedlesaness ^ia Some Inedible Fruits Which May Be Transformed —Even the Acrid Barberry Is Changing ••••••••< IX The Need for Improving Small Fruits —And Some of the Means For Meeting It List of Direct Color Photograph Prints .......... 305 349361 FOREWORD TO VOLUME VI In this volume Mr. Burbank tells how he produced the thornless blackberry, the white blackberry, the new thornless raspberry, and all of those other berry transformations which excite endless wonder in the minds of the uninitiated — yet which were produced by methods so simple, once understood, that they seem no more wonder- ful, after all, than their conventional cousins, with which, since childhood, we have been familiar. In this, as well as in the other volumes, there are indications, and suggestions, wherever pos- sible, of other improvements which are needed, and an outline of the ways in which there is likelihood that they may be brought about — with always a view to the practical betterment of existing berry patches. THE EDITORS. Mr. Burbank at Work Mr. Burbank is here selecting among boxes of second-gen- eration thornless blackberry hybrids. Some of these speci- mens are a cross between lh". thornless blackberry and the white blackberry; others between the thornless and the Himalaya blackberry. Through these experiments Mr. Burbank hopes to rid all of our best varieties of black- berries of their thorns. THE THORNLESS BLACKBERRY —AND OTHERS SOME TRANSFORMATIONS IN THE BRAMBLE PATCH THE nursery rhyme about the wise man and the bramble-bush will probably have little meaning for our grandchildren. For the brambles of their day will have no thorns with which to scratch out eyes — let alone scratch them in again. This, I think, is a fairly safe prediction, for the thornless blackberry is an accomplished fact, as anyone who has visited my gardens can testify; and the value of thornlessness in a berry-produc- ing vine is so obvious that the new product can hardly fail to supplant the old type of briar bush quite rapidly. Whoever has visited a blackberry or raspberry patch of the old type and attempted to gather the fruit, will recall, doubtless, bringing away sou- venirs in the form of scratches that were far more lasting than the fruit itself. [VOLUME VI — CHAPTER I] LUTHER BURBANK When any visitor who has the recollection of such souvenirs visits my garden and sees mam- moth clusters of beautiful blackberries growing on vines as smooth as pussy willows, the impres- sion gained is both vivid and lasting that here is a plant improvement of a very notable order. In point of fact, there is perhaps no other sin- gle plant development in connection with small fruits that constitutes so radical a change and so conspicuous an improvement as the removal of thorns from the blackberry. The bush itself no longer needs the thorns to protect it against ma- rauding deer or sheep as it did in the days when it grew in the woodland or nestled in fence cor- ners. On the contrary, as we have elsewhere sug- gested, the thorns are now detrimental to the plant in that they take a certain amount of energy and building material that might be put to a bet- ter use. And from the standpoint of the horticulturist, the thorn is not merely a detriment; it is a nui- sance of such significance as materially to inter- fere with the cultivation of the blackberry and very greatly to reduce its popularity. It may confidently be predicted that, once the thornless blackberries are generally introduced, the really delicious fruit that they bear will be seen far more commonly in the market than it [8] - " &• » ~. ft S3 a I LUTHER BURBANK has been in the past, and will soon achieve the popularity that it deserves. How THE BLACKBERRY LOST ITS THORNS As long ago as 1880, while I was still following the pursuit of a practical nurseryman and giving only incidental attention to plant development, I made experiments in the attempt to produce thornless berries. But these experiments were nearly total failures. The plant with which I worked was a black- berry bush known as the Wachusetts Thornless, which was introduced and alleged to be thornless about 1880. I raised seedlings from this plant, and also crossed it with other blackberries. But I was much preoccupied with other experiments and was greatly handicapped for means, and therefore neglected to carry the experiments to a practical conclusion. In point of fact the Wachusetts, which had been found partially thornless in the state of na- ture, had a goodly supply of thorns distributed here and there over the plant. It had fewer briars than most other blackberries, to be sure, but it was by no means the sort of bush to handle with impunity or rub against your face without the slightest danger, as may be done with the thorn- less blackberry of to-day. The Wachusetts was not of a really smooth [10] ON THE THORNLESS BLACKBERRY stem, and it had almost nothing else to commend it. Its berries were quite small and lacking in flavor, and it had moreover the pestiferous habit of suckering from the roots. So it naturally did not achieve popularity. Nor was anything heard of any other blackberry that laid claim to thorn- lessness until about ten years later. Then it chanced— in the year 1902 I think it was— that Mr. David G. Fairfield, of the United States Department of Agriculture, found in North Carolina a few plants of a wild dewberry, ap- parently Rubus Canadensis, that were nearly thornless. Mr. Fairchild had frequently furnished me specimens of one kind or another that he thought might be useful in my work. He now very kindly sent me a few ripe berries picked from the partially thornless dewberry. The seeds were carefully planted in boxes in my greenhouse. Of the several hundred seedlings that these produced, probably about one or two in the hundred were nearly or quite destitute of thorns. These few thornless plants were carefully se- lected, all the remainder being destroyed. From the fruits borne by these selected plants, a second generation was raised, from among which it was possible to select a great number that were absolutely free from thorns — showing LUTHER BURBANK no sign of any spicules on either stems or leaves. More than fifteen thousand seedlings were raised from the fruit of the best of these thorn- less plants, and out of that large number not a single specimen showed any tendency to develop thorns, every one being as smooth as the branch of an apple tree. Thus by inbreeding and selection from fruit produced by a partially thornless wild dewberry, I quickly developed a race of thornless berries that could be depended on to breed absolutely true as to thornlessness. If we interpret the facts of this development, in the light of later experience, we may infer that the condition of bearing thorns is prepotent or dominant over the condition of thornlessness in the blackberry. Thornlessness is, then, a reces- sive trait which will be submerged in a cross be- tween a thorny bush and a thornless one, but which will reappear after the manner of recessive traits, in a succeeding generation, provided two individuals of mixed heritage are interbred. The fact that only a small percentage of my first seedlings grown from the seeds Mr. Fairchild sent were thornless, suggests that the flowers of the bush on which they grew had been chiefly fertilized with pollen from thorn-bearing bushes. The fruit from such a pollenization would pro- [12] LUTHER BURBANK duce thorny bushes exclusively, owing to the dom- inance of the factor for thorns. But if a few ber- ries or individual drupelets of a berry had been fertilized with pollen from a flower of the thorn- less plant itself, these would (according to a for- mula with which we are already familiar) stand one chance in four of combining recessive fac- tors and thus of producing thornless progeny. And of course from there onward the case pre- sented no difficulty. The plant experimenter was now at hand to make sure that the thornless flow- ers were fertilized solely with pollen of their own sort. This of course could bring together only recessive factors, that is to say, factors for thorn- lessness, and the result could not be in doubt. The thorn-producing factor would be left entirely out of the composition of bushes sprung from such a union, and they would inevitably be thorn- less. THORNLESS, BUT LACKING QUALITY But while the production of a thornless race of dewberries was thus accomplished with com- parative ease, once the material with which to work had been supplied, it must be understood that this was really only the beginning of the task. The original berries from which the thornless vines were grown were of no commercial value. They were small and of very indifferent flavor. [14] ON THE THORNLESS BLACKBERRY To have produced a thornless race from them was an interesting scientific achievement, but one that at this stage had no practical significance. In order that the experiment should lead to the practical results at which I aimed, it was nec- essary now to improve the fruit of my thornless proteges. And, while something could be done in this regard by mere selection — in which case, of course, there would be no danger of having the plants backslide from a thornless condition — I soon found by experiment and observation that selection alone would be much too slow and doubtful a method for the development of such fruit as would be necessary to compete with the highly developed blackberries already in the market. For of course it could not be overlooked that the ultimate purchaser is much more vitally in- terested in the quality of fruit supplied him than in the question of whether this fruit grew on a thornless vine or on a briar bush. By the time I had reached the conviction that it would be necessary to adopt a more energetic procedure than mere selection in the education of the thornless berries, I had acquired through experience a very clear comprehension of the methods that must be depended on to inculcate the desired lessons. I knew that crossbreeding [15] LUTHER BURBANK afforded the only feasible means of introducing good qualities into the fruit of the thornless dewberries. Now the work of development took on aspects closely comparable to those that we have already reviewed at length in the development of orchard fruits. It was necessary to bear in mind such items as increased size of fruit, good flavor, firm flesh, and time of ripening — all of these being matters regarding which the thornless berries were defective. IMPROVEMENT THROUGH HYBRIDIZING Of course there was no dearth of material with which to effect hybridization. The dewberry is merely a trailing variety of blackberry, and it crosses readily with all other species of blackberry. I had at hand any number of blackberries bearing fruit of the finest quality. There would probably be no difficulty whatever in producing hybrids between the little thornless berry and the Lawton blackberry, for example, or my new Himalaya berry, or any one of a dozen others. And some of these would give, among varying seedlings, a certain member that would bear ex- cellent fruit. But, unfortunately, when such crosses were made, it was at once apparent that the thorny [16] LUTHER BURBANK condition had shown prepotency, and ajl the seed- lings that grew from thornless berries thus cross- fertilized were at once seen to be bearers of thorns. This was precisely the experience that had dis- heartened me, when, back in 1880, I had made the experiments with the Wachusetts partially thorn- less blackberry, to which reference was made above. But in the intervening time I had made many thousands of hybridizing experiments, and I now clearly understood — what at the earlier period I had known vaguely if at all — that in such a case as this we must look to the second filial generation for the kind of results we are seeking. The case is precisely comparable to that of the white blackberry, for example, or to that of the stoneless plum. When the white blackberry is crossed with a black blackberry all the off- spring of the first generation are black. And when the stoneless plum is crossed with the stone-bear- ing plum all the offspring of the first generation are stone-bearers. But in each of these cases the succeeding generation will show individuals in which the submerged character reappears — we shall have white blackberries and stoneless plums agkin. So I had every reason to believe that a com- parable result would be achieved if the thorny [18] ON THE THORNLESS BLACKBERRY hybrid seedlings born of my thornless race were given opportunity to redeem themselves in their progeny. The expectation was justified. In the second filial generation the thorny seedlings produced a certain proportion of thornless progeny. And these thornless bushes now bore fruit far superior to that of their thornless grandparent. They had inherited some of the good fruiting qualities of their thorny grandparent, even though they had repudiated his thorns. This was obviously encouraging. So the ex- periment was continued along the same lines through successive generations. I selected, of course, the specimen in each generation that showed the best combination of desired qualities and hybridized, in successive generations, the Lawton blackberry, the giant Himalaya, and vari- ous others, to gain size of berry, earliness of bear- ing, new flavors, more acid, and, in a word, to supply whatever defects could be discovered. The original thornless berry was a late bearer, and its fruit lacked size, spiciness, and refreshing acidity. But these qualities were supplied in good measure through successive crosses. One seedling in particular, grown in 1906, showed exceptional qualities, and the subsequent stock was largely grown from the fruit of this sin- [19] LUTHER BURBANK gle bush. Like its fellows, it bore strains of half a dozen races of high-grade market berries, blend- ed with the thornless strain. Of course each successive hybridization with a bearer of good fruit meant the introduction of thorns in the seedlings of the next generation. This was inevitable, since of course all the bear- ers of commercial blackberries were bearers also of thorns. The Himalaya in particular is an ex- ceedingly thorny bush, and the otherwise com- mendable Lawton is an almost equal offender. But whereas these thorny shrubs were prepotent in their influence over their direct offspring as was expected, some of their grandchildren always reverted to the thornless state. And so here as in various other experiments already described, advance was made by indi- rection. We are forced to seesaw back and forth in successive generations between thorny bushes and thornlessness; yet on the whole there was progress, inasmuch as each successive generation showed better qualities of fruit, and each alter- nate generation the recurrence of the thornless condition. Inasmuch as the thornless bushes, of whatever generation, will breed true to thornlessness if fer- tilized among themselves, it is obvious that each thornless generation constitutes a fixed race, pro- [20] Thornless Blackberry and the Recreant Seedling At the left, a typical stem of Mr. Bnrbank's thornless blackberry; at the right, a thorny seedling. The thornless blackberry almost invariably breeds true to thornlessness ; so it is to be surmised that this seedling is the result of a chance fer- tilization with the pollen of a thorny variety. LUTHER BURBANK vided the plant experimenter does not elect to disturb its fixity by a new hybridization. The result, up to date, is that after twenty years of selective breeding along these lines, the descendants of the little North Carolina dewberry (who are descendants also, of course, of various and sundry berries of more aristocratic bearing) constitute a race of blackberries growing on large, well-shaped, spreading bushes that are absolutely thornless. The fruit itself is a large, handsome, glossy black berry, of excellent flavor, profusely clustered — a fruit that makes inviting appeal to the wayfarer and which will exact no penalty in the way of scratches from those who gather it. I have told thus at length the story of the thornless blackberry, because the development of this fruit quite eclipses all my earlier work with the blackberries, and makes the record of the de- velopment of the thorny varieties, however excel- lent their fruit, seem an almost archaic per- formance. It must be recalled, however, that the present thornless blackberries of quality could not have been secured so expeditiously had not material been at hand for the hybridizing experiments through which size and flavor were bred into the fruit until, as just related, the perfected thornless varieties were developed. [22] *3?&ff||, i|ii!*i!*t*» * • ~2 >e, 2 2.E « 5 c* 3 c* * 3* LUTHER BURBANK And this material was largely the product of earlier experiments through which blackberries of the old type had been improved as to their fruiting qualities. It is necessary, therefore, in the interests of completeness, to retrace our steps and briefly to review the earlier experiments — some of which, indeed, were carried forward coincidently with the development of the thornless — through which new races of blackberries of exceptional quality, though still handicapped by thorns, were de- veloped. In connection with this story it is interesting to recall that the cultivated blackberry is essen- tially an American product. No other country until quite recently has appreciated the quality of this fruit sufficiently to cultivate and develop it. Wild species, to be sure, are abundant in Eu- rope, growing everywhere in England and in Ire- land, along hedges and in waste places; but the horticulturist has all along seemingly been preju- diced against the fruit, partly perhaps because of its offensive briars. The prejudice against the wild bramble was retained by the Colonial settlers of America — re- tained so persistently that fully two centuries were needed for this excellent berry to make its way into the fruit gardens. [24] ON THE THORNLESS BLACKBERRY Not a single horticultural variety of black- berry was introduced until almost the middle of the nineteenth century. Then the Dorchester was brought to notice, and about a decade later a better berry, the Lawton, which is still a standard, and two other varieties, the Holcomb and Wil- son's Early, were brought to the attention of fruit growers. As a significant industry, blackberry cultiva- tion is even more recent. It has almost wholly developed since 1870. It began with planting, on a commercial scale, the Lawton, which was later supplanted by the Kittatiny in some sections. This in turn gave way to the Snyder, and still more recently better varieties were developed. The evolution of the fruit had been gradual, but it has at last established a place in the horticul- tural ranks. I repeat my prediction that it will gain a new impetus now that the one great draw- back of the blackberry, its thorny stem, has been eliminated. It will take some time, howrever, to spread the thornless berry universally, and in the meantime the blackberries of the older type retain a meas- ure of interest. MATERIALS FOR DEVELOPMENT The chief American wild species, which fur- nished material for the development of the races [25] LUTHER BURBANK just named, are the common Eastern blackberry (Rubus nigrobaccus) , familiar everywhere throughout northeastern America, and a closely related form, considered by some botanists a mere variety, known as Rubus sapivus. The common wild plant is an upright grower, stout, has little recurving canes that are usually deeply furrowed lengthwise, and clothed with stout more or less hooked prickles. The other species or variety is slightly more erect, with fuller and firmer canes, differing some- what also as to shape of leaves. It bears berries that are usually rounded, generally soft and juicy, and of superior flavor. At my old home in New England this variety grew abundantly on sandy soil, being one of the best wild blackberries in that vicinity. I early noticed that this plant was inclined to vary widely. For example, the vines, although usually stiff, upright growers, some- times more resembled the common blackberry, or even tended to take on the trailing habits of the dewberry. When I came to know more about plant de- velopment I recalled this tendency to variation, and felt that here, as always, a fruit of this ten- dency should furnish material for the develop- ment of improved varieties. In due course I worked with the various culti- [26] ON THE THORNLESS BLACKBERRY vated varieties of blackberry, and soon developed some improvements, particularly with reference to the size of fruit, its flavor, and lengthening the season of fruit bearing. One of the improved varieties with which I worked had been lately introduced under the name of the Early Harvest; another was named Wilson Junior. But my most notable results at- tended the use of the native species, and in par- ticular the introduction of foreign species from remote parts of the earth. As early as 1879 I was earnestly working on varieties of blackberries, and of raspberries as well, that were obtained from my collector in Ja- pan, combining these with other wild and culti- vated varieties from various sources. My first really notable success, however, came about through selection, without the aid of hy- bridizing, from a berry that I introduced from India. This berry, in recognition of its origin, was named the Himalaya, sometimes shortened to Himalya. THE PROLIFIC HIMALAYA The seed from which this improved blackberry grew was obtained from India through exchange. It would appear that transplantation to an altogether new soil and climate had the same stimulating effect upon this blackberry that we [27] A Thorny Climber Beside the back fence of Mr. Burbank's garden at Santa Rosa there grow, within a few feet of each other, two black- berries which never fail to excite wonder. One is the typical thorny type shown above; the other is the absolutely smooth thornless blackberry — a complete transformation. The u;or- like capacities of the thorny blackberry bramble are familiar to everyone who has ever gathered blackberries. A Thornless Contrast This is the thornless blackberry growing beside the thorny one shoivn in the preceding picture. Not only have the thorns been completely removed, but the cane, as can be seen, has covered itself with a downy film, comparable only to the bloom which grows on plums. The plant shown here has possibly 100 feet of stalk and stem, every inch of which could be rubbed across the face without injury. LUTHER BURBANK have seen manifested in the case, for example, of the Japanese plum, the New Zealand winter rhu- barb, and sundry other plants. For there ap- peared among seedlings of the second generation an individual that showed a very marked im- provement over its parents. This exceptional seedling was cultivated and propagated, and its qualities proved so unique that it was introduced in 1885 by a special circu- lar, being christened, as just stated, the Himalaya. After the usual decade or so of probation, dur- ing which every new fruit of whatever quality must wait for recognition, the Himalaya took its place, first on the Pacific Coast, and later through- out the northern and central states, as a standard blackberry. After it came to its own, so to speak, its popularity was so great that for several years the plants could not be multiplied fast enough to meet the demand. It is a plant of extraordinary vigor. A single cane may grow more than twenty-five feet — some- times even fifty feet — in a season, and attain near the base a diameter of an inch to an inch and a half. The aggregate growth of cane of a single plant in a season may exceed a thousand feet — one fifth of a mile. And in point of fruit production, the Himalaya [30] Thornless Blackberry Buds The thornless blackberry is of mixed ancestry, the pro- genitor from which the thornless quality is inherited being a wild dewberry. Thornlessness in a brier seems almost a contradic- tion of terms, but it will be seen that the buds and leave* have characteristic blackberry qualities. LUTHER BURBANK far surpasses any other berry plant ever grown. Reports tell of a single bush bearing two hundred pounds of berries in a season. "My daughter and I picked fifty pounds of ber- ries from one Himalaya bush the latter part of August, 1906," writes one enthusiast, "and we scarcely missed them from the bush. This was after many others had picked from the same bush. I picked three pounds standing in one position. I could have picked double that amount if I could have reached into the bushes farther, but the en- tangled branches with their sharp thorns pre- vented me." The narrator adds this comment: "It is my opinion that if this bush were properly pruned, fertilized, and irrigated, as well as shaded from the extreme heat of the sun in July and August, it would bear between three and four hundred pounds in a season." Such a report is typical. The prolific bearing of the Himalaya is the subject of astonished com- ment from everyone on seeing this extraordinary vine for the first time. The fruit itself is of medium to large size, un- usually sweet, and spicy, with small seeds, and fine in quality. The berries grow in clusters some- times a foot or more across, and they continue to ripen after most other blackberries are gone. [32] Blackberry Blossoms As to blossom also, the Thornless is a typical and charac- teristic blackberry. The smooth stem may make one doubt, but observation of the flower will convince any pessimist that this is a true blackberry. LUTHER BURBANK If not pruned, the vines of the Himalaya will grow to a length of one hundred feet or more, like grape vines. They appear to be absolutely resistant to disease, and they have recently shown the ability to resist the extreme cold of Michigan and the far northern states. It should be known that the Himalaya takes a year or so more to come to its best bearing condition than ordinary black- berries, but when in full bearing a single plant will produce as much as a dozen ordinary black- berries. The elimination of the thorns is a matter to which sufficient reference has already been made. As to abundant bearing, nothing more is to be desired. The Himalaya at present produces all the berries that a vine can possibly support. DEVELOPMENT THROUGH HYBRIDIZATION As the experiments in the development of the blackberries continued, I quickly passed from the stage of mere selection to that of crossbreeding and hybridization. The plants utilized in these experiments in- cluded not only all types of native blackberries proper, and numerous foreign species, but plants of the allied race of dewberries. The dewberry, to be sure, is closely related to the blackberry; it is, indeed, a blackberry that has assumed a trailing habit. Or possibly the case [34] ON THE THORNLESS BLACKBERRY would be stated more truly if we say that the bush of the blackberry is a dewberry that has risen from the ground and assumed the habit of up- right growing. There is, nevertheless, a sufficient divergence to make the dewberry seem to casual inspection a plant of distinct type. And, at the time when my experiments were begun, there were probably few plant developers who would have supposed it possible to hybridize even the dewberry with the ordinary blackberry. Successive crosses were effected, nevertheless, at an early stage of the work, and in the course of my experiments the interblendings were so nu- merous and intricate that seedlings were pro- duced showing all gradations of habit between the trailing vine and the upright one; as well as all gradations of leaf and fruit form and quality. Sometimes in crossing a blackberry with a dewberry the trailing habit is greatly intensified, the hybrid being a long, vine-like, straggling plant. Again, the result may be just the opposite, a tall, upright, almost tree-like plant being produced. Some hybrids would run a distance of at least fifty feet. Others, perhaps of the same fraternity, would take on so tree-like a habit that their fruit could be reached only with the aid of a step- ladder. [35] LUTHER BURBANK But perhaps the most singular and interesting anomaly was that some of these hybrids bore flowers and fruit in every month of the year, though sparingly. At the time when I had a large colony of blackberry-dewberry hybrids, ripe ber- ries could be picked from one bush or another almost every day of the year. The possibility of producing, with the aid of such hybrids, commercial varieties of blackber- ries that will fruit at all seasons is inviting. Ex- periments already far advanced have greatly ex- tended the blackberry season, and there is reason to expect that the blackberry lover in the future will be able to secure this fruit, in one variety or another, from early spring until almost the onset of winter. As to other possibilities of blackberry devel- opment, something was said in the earlier chap- ter that described the development of the white blackberry. But much remains to be told. The chief development, however, through which not merely new varieties but new species of berries have sprung from the amalgamated stock of the forty-odd species of bramble fruit with which I have experimented, have had their origin in hy- bridizations that linked the blackberry with its relative the raspberry. The account of the altogether notable results [36] I o uif»i'i&»ii ft 3 » « 2 LUTHER BURBANK that have arisen from this alliance is an integral part of the story of the blackberry. But it may be told to best advantage in connection with the story of the raspberry in the succeeding chapter. — The thornless blackberry is an accomplished fact, and the value of thornlessness in a berry producing vine is so obvious that the new product can hardly fail to supplant the old type of briar bush quite rapidly. THE RASPBERRY AND SOME ODD CROSSES MUCH BETTERMENT — AND A FEW BAFFLING PROBLEMS LET us take up the story of small fruit de- velopment where the preceding chapter left it. We are still concerned with the blackberry, but we now have to do also with the companion fruit, which is obviously a not very distant relative, yet which has certain typical pe- culiarities that mark it as belonging to an alto- gether different branch of the race of brambles. Most conspicuous of these is the fact that the ripe raspberry separates from the receptacle when picked, whereas the blackberry is permanently at- tached to the receptacle. The raspberry, unlike the blackberry, has been cultivated in Europe from an early period. The red raspberry, in particular, grows wild all over Europe, from Greece to Spain and northward to Norway and Sweden. It was originally christ- ened Rubus Idaeus, after Mount Ida in Greece. [VOLUME VI — CHAPTER II] LUTHER BURBANK Like other cultivated plants, it tends to vary, and it is said that more than twenty varieties were under cultivation in England a century ago. The American colonists introduced this favor- ite European berry at an early date, but it did not find a congenial environment in the new coun- try. The long, cold winters of the northern states, and the dry heat of the southern summers were alike hostile to it; and its lack of hardiness denied it general recognition except as an occasional gar- den plant. But the new continent possessed many wild raspberries that were of course adapted to the environment, and in time these came under cul- tivation. Their introduction, however, was so gradual that it was quite unnoticed. The only raspberry cultivated extensively for the New York market early in the nineteenth century was known as the English Red. It is believed to have been an offspring of a native berry, known as Rubus neglectus (itself believed to be an accidental hy- brid of our wild red and black raspberries), but this was not generally known, and the name given the fruit suggests that it was supposed to be of European origin. During the latter half of the nineteenth cen- tury many improved red and yellow raspberries were introduced, and various of these have been [401 The Familiar Blackcap This is the familiar wild black raspberry or Blackcap, sometimes spoken of as the Longworth Blackcap. The speci- mens here shown are better than the average run, having been im- proved b;i Mr. Burbank by means of selection. They rep- resent the species unmodified by crossing, however. LUTHER BURBANK utilized in the course of my hybridizing experi- ments. But perhaps the chief favorite among Amer- ican raspberries is the one introduced in the early forties by Nicholas Longworth, of Ohio, and known as the Wild Black or Black-cap Raspberry, Rubus occidenialis. This berry was a great addition to the list of cultivated fruits. It soon became a favorite ev- erywhere it could be successfully grown. Mr. Longworth himself introduced it into England, but it did not thrive in the English climate and it never competed with the native European species. INTERBREEDING THE RASPBERRIES The familiar cultivated raspberries of the pres- ent time owe their origin to the species just named, and to two other allied species, one our wild red raspberry, Rubus strigosus, a close rela- tive of the common European species, the other known as Rubus leucodermis, a western relative of the familiar black-cap. All the red raspberries now under cultivation have sprung from either the European or Amer- ican red species. The Purple-cane type appar- ently sprang from the Rubus neglectus (very probably a hybrid between R. strigosus and R. occidentalis) ; such varieties as the Reliance, Shaf- [42] ON THE RASPBERRY fer, Philadelphia, and Gladstone are, at least in part, probably of this origin, as was the historical English red. The Purple-cane was a native of the northeastern part of the United States, being especially common in New York. The original American red raspberry, Rubus strigosus, first became known to the horticultural world in 1860, through the introduction of Allen's Antwerp and Allen's Red Prolific. For several years preceding 1880 I had been raising seedlings of blackberries, raspberries, gooseberries, Juneberries, strawberries, currants, and various other berries on my experiment farm, and many variations were developed in that way which aroused my enthusiasm. These experiments were largely instrumental in teaching me the then not known or not gener- ally accepted value of cross-pollenizing as the means of introducing the tendency to vary among existing species or varieties. And my experiments with the different raspberries had a prominent share in the demonstration of this very important and hitherto unappreciated principle. In the course of these experiments it was first found that the black-cap would cross with the red raspberry, although with difficulty. Seedlings from this cross sometimes bore per- fect berries abundantly, but much oftener they [43] LUTHER BURBANK bore imperfect berries having perhaps only two or three seeds. Again, after blooming, there would be no development of fruit, only a core or stem remaining. Among some of these crosses I met with a dif- ficulty not encountered in crossing any other of the members of the great Rubus tribe. The plants at first seemed sickly, having little or no vitality. When transplanted from greenhouse to open field they made little growth the first season and the second season at about the time for fruit bearing they all seemed to fail utterly. Every seedling among a lot of these hybrids would sometimes thus be suddenly destroyed. In continuing the experiment, I found that there was strong individuality among the differ- ent plants, so that some of the red or yellow rasp- berries crossed readily with the black-caps, while others failed to do so; there being all gradations. In some cases the resulting seedlings would show the prepotency of one parent or the other. But, generally, in the first generation, there would be a blending of the characteristics of the two. UNDERLYING PRINCIPLES At that time no plant developer fully realized that all the best variations and recombinations in a hybrid stock appear in the second and a few succeeding generations. A recognition of this [44] .:'. rf^v' 1 A-J£ ^J r .ttT \ -v If? ^HaBisFg.B a ^ ||>lN,a|i||*'*j| g S.a.7 LUTHER BURBANK principle constituted my first very important step toward the development of new forms of plant life. I discovered, in connection with the raspberry hybrids, that in the second and a few succeeding generations different combinations were brought out in the most wonderful variety; and that from these certain individuals could be selected hav- ing almost any qualities of either parent com- bined in almost all possible proportions, and often greatly intensified. This was, as we now know, substantially the discovery that Mendel had made almost twenty years before. But no one heard of his discovery till long afterward (about 1900), and at about the time when I was independently learning the same lesson Mendel himself died, quite unknown to fame, without having been able to bring his dis- covery to the attention of the scientific world. Meantime, without formulating the principle in precise terms as Mendel had done, and without following up results with numerical exactness, I came to full recognition of the principle of blend- ing of characters in the first filial generation and their reassortment and segregation in the second and succeeding generations. All my experimental work was carried for- ward with a clear recognition of that principle. [46] ON THE RASPBERRY As to the work with the raspberries, my first aim was to accumulate as much available mate- rial as possible. This has been my custom throughout The chances of obtaining results from a large number of experiments are proportionately greater as the number increases, and I find, within limits of time, that it is just as simple to conduct a thou- sand or ten thousand experiments, or even a hun- dred thousand experiments, as to conduct a few. So I worked on a comprehensive scale with the raspberries from the outset; and it was not long before I developed several varieties of value; varieties, in fact, superior in size, quality, and productiveness, to any raspberries hitherto known. FIRST FRUITS OF THE EXPERIMENTS The first of my new raspberries offered to the public was named the Eureka. This raspberry, introduced in 1893, was de- scribed as "larger than any raspberry in cultiva- tion; bright red, firm, very productive, and sim- ilar to Shaffer's Colossal in its piquant acid flavor. It is nearly twice as large as Shaffer's Colossal, its great-grandparent, and a better color and qual- ity, firmer, handsomer, and in all respects an im- provement on that well-known variety. The bushes are more compact in growth, almost free from prickles, and of a sturdy appearance." [47] LUTHER BURBANK Particular attention should be called to the fact, just stated, that the new raspberry was al- most thornless. This was true of a number of my raspberries, as by selective breeding I was able to give these vines smooth stems at a time when my similar attempts to remove the thorns from the blackberry had not been successful. The difference was due, perhaps, to the fact that the raspberry, having been long under culti- vation, had partly lost its thorns through more or less unconscious selection on the part of many generations of fruit growers. The thorns had been reduced in many varieties to prickles, and occasionally individual specimens appeared that lacked even these. By selective breeding from such specimens I was able to produce varieties that had practically smooth vines. A selected seedling of the Eureka was remark- able for its habit of bearing in October as well as for the enormous size of the berries, which were frequently almost four inches in circumfer- ence. The berries were of a beautiful bright red, but were rather too soft except for home use. Another of my crossbred raspberries, orig- inated at the same time with the Eureka, was called the Dictator. This also is a mammoth bright red berry. It combines the flavors of the Gregg and Shaffer's Colossal from which it orig- [48] Thornless Raspberry Among other things, the experiments that produced the Eureka pointed the way toward the development of a thorniest raspberry. The stems here shown sufficiently demonstrate that this ideal was attained. A picture of the thornless raspberry has been given in Volume I. LUTHER BURBANK inated. The combination is one of the happiest, as the acidity of one is modified by the sweetness and aroma of the other. The berries were more than three times as large as those of the Gregg, and almost twice as large as those of Shaffer's Colossal, which until the production of these new hybrids bore the largest raspberries known. Another cross of the Gregg, this time with the Souhegan, produced a seedling that had astonish- ing crops of fine, medium-sized, red berries, that ripened during October. The Souhegan was also crossed with the Shaffer, and this union produced in the second generation a new variety that was known as the Sugar. From the seeds of other members of this same generation two or three other promising berries were produced. One of these bore large, firm ber- ries, conical shaped, and a dark rich purple color. A NEW SPECIES — THE PRIMUS BERRY All the raspberries commonly known to the cultivator, and many new ones that I imported from Asia and the Southern hemisphere, were growing on my grounds from 1890 to 1900, and were intercrossed very extensively. Numbers of highly interesting hybrids were thus produced, and at least one of these was of so distinctive a character as to merit the title of a new species. T50] The Dictator Raspberry This was another of the crossbred raspberries originated at the same time with the Eureka. This also is a mammoth ^ bright red berry. It combines the flavors of the Gregg and the Shaffer 9 Colossal, from which it originated. The combination is one of the happiest, as the acidity of one is modified bg the sweetness and the aroma of the other. LUTHER BURBANK This was the fruit that was introduced as the Primus berry. This highly interesting fruit, one of the first plants of any kind that could properly be termed a new species to be developed under the direct guidance of the hand of the experimenter, was the progeny of a hardy little berry indigenous to Si- beria and Russia, called the Siberian raspberry (Rnbus crataegifolius), and the California dew- berry. The little hardy Northern raspberry bore fruit about the size of a pea, of a dark mulberry color, with rather large seeds, and a flavor not such as particularly to commend it. It is, however, re- markable for its large palmate leaves, and the sturdy growth of its stems. The California dewberry, Riibus bitifolius, is a trailing vine which is extremely variable in fo- liage, habit of growth, size, and quality of fruit. It is found wild everywhere in the foothills and lower elevations throughout the Pacific slope of the United States, but seems to be at its best in Northern California and Oregon. The berries of this wild species are often produced abundantly. They are black, usually of good size, and of su- perior quality. They are often gathered in large quantities for market and home use. The fact that the dewberry bears so-called di- [52] ^tj r^ ~,< , *** 33 gS^S^S^rS-o^g^^^-a liirttlfRlnll LUTHER BURBANK oecious flowers — that is, flowers of opposite sexes on separate plants — has discouraged a very gen- eral cultivation of the plant. It is necessary to grow both male and female plants to ensure fer- tilization, and fruit growers do not relish the idea of having half their vines unfruitful. Nevertheless there was one variety of the Cal- ifornia dewberry, called the Aughinbaugh, which had been under cultivation for several years. This was the one selected for most of my experiments in hybridizing the dewberry; and this plant had a share in the production not only of the Primus berry, but of the even more remarkable Phenom- enal berry to which reference will be made in a moment. The cross between the Siberian berry and the California dewberry, from which the Primus sprang, was made without particular difficulty. I had learned by this time that blackberries and raspberries and dewberries could be hybridized almost indiscriminately; and the fact that one of the parents in the present combination had grown originally in Siberia and the other in California offered no barrier to the union. With the first lot of seedlings, five hundred or more, from this union of the California dewberry and the Siberian raspberry, some strange speci- mens were revealed. [54] A Natural Hybrid This natural hybrid raspberry was found growing wild by Mr. Burbank in Alberta, Canada. It was brought to Santa Rosa, and has been used in various hybridizing experiments. The chief interest of the plant, however, is that it is a natural hybrid that was growing in a state of nature, and appar- ently competing successfully with both of its parents. LUTHER BURBANK Nearly all were worthless plants, some of which seemed hardly to have vitality enough to live, much less to produce fruit. Others bore small, unattractive herries, insignificant in every respect. Three or four individuals, however, grew with unusual vigor. They differed so widely from the others that I was at first inclined to suspect that they were dewberries unhybridized. As to this, however, I was in error. One of these exceptional vines was particu- larly notable. It neither trailed nor stood up- right, but took an intermediate position. The leaves were not palmate like those of the rasp- berry, nor were they like the foliage of the dew- berry. They were a compromise between the two. The fruit, which was larger than that of either parent, resembled the blackberry most in form, but was of a dark mulberry color. When the fruit was just ripe it parted from the stem like the blackberry; but when fully ma- ture the core came out as it does in the raspberry. Thus the combination of all these important characteristics was almost absolutely complete. The hybrid was a perfect blend. It was this plant that was christened the Primus berry. Seedlings by the thousand were raised from this selected hybrid and all of them came as true [561 ON THE RASPBERRY as the seeds of any wild species of the family. The offspring closely resembled the Primus, but none of them quite equaled it in fruiting qualities. If found growing wild, the original Primus plant and its progeny would be pronounced by any botanist a distinct species. The explanation of the summary production of a hybrid differing in this remarkable manner from either parent and being so fixed in type as to breed true to the new form thus suddenly de- veloped would seem to be that the two parent species were separated almost to the limits of af- finity. The fact that most of the hybrids of the same generation with the Primus were feeble and degenerate creatures is corroborative. It ap- peared, however, that there were elements in the two types of germ plasm that if combined in just the right way would produce a virile offspring. By chance the right combination was effected, and the Primus berry was the result. The berry itself has not proved a great com- mercial success, but that is a matter of small im- portance. The real importance of the experiment was in what it proved as to the possibility of the production of new species through hybridization. This was, in short, one of the first instances to come under my observation of the production of a hybrid that blends the characteristics of the [57] LUTHER BURBANK parents, producing a new type and breeding true to that type. To my mind — and I think the facts are con- vincing to any unprejudiced mind — this and many similar experiments that have been successfully accomplished demonstrates beyond dispute that hybridization is one of nature's methods of cre- ating new species. I have dwelt at length on this subject in ear- lier chapters. I revert to it here because of the importance of the subject itself, and also because the Primus berry furnishes us a new and striking illustration of the truth of the principle. Of course the Primus berry was produced by artificial pollenizing of the plants that were so located geographically that they would have had no chance to hybridize unless brought together by man. But my observations show that natural hybrids are not at all unusual among wild mem- bers of this family. I have met with them often where two or three closely related species were growing side by side. Near Lake Sycamour, for example, at Alberta, Canada, I have observed two common raspber- ries, Rubus leucodermus, a red raspberry, and Rubus strigosus, a black-cap, growing in close proximity around the hillsides and along the streams. [58] ON THE RASPBERRY In every case where I found these two species growing together there were numerous natural hybrids in evidence. None of these hybrids were as productive as the parents, but the vines were usually stronger growers than either, and ap- peared to be hard pressing both parent species, with the prospect that they would in time sup- plant them in this region. I gathered large quan- tities of seeds from the best of these hybrids and brought them home for planting. Many seedlings were thus raised which obviously carried the com- bined characters of both their wild parents. These representatives of a new species devel- oped by hybridization under natural conditions have obvious scientific interest even though they failed to develop sufficient productivity to be of commercial value. Let me repeat that natural hybrids are much more numerous than is generally supposed. I have found them among other wild plants. Especially are they to be observed among straw- berries, blueberries, huckleberries and California lilacs (Ceanothus). I have elsewhere cited in- stances of the hybridization of the tar-weeds and the mints. There can be no doubt that some of our well-known species of to-day were produced by Nature in this way within recent times. I have elsewhere observed, and I emphatically [59] LUTHER BURBANK repeat, that any theory of the origin of species that does not recognize this among the methods employed by Nature for the production of new species is altogether inadequate. ANOTHER NEW SPECIES — THE PHENOMENAL BERRY The result of thus mating the dewberry with the little raspberry from an almost Arctic climate having proved so remarkable, almost numberless tests were made in which the dewberry was crossed with a great variety of other raspberries and blackberries. And among the hybrids thus produced there was at least one that might be considered more remarkable even than the Primus berry. This was the fruit which afterward became famous as the Phenomenal berry. This extraordinary berry was the outcome of a series of experiments in which the red and yellow raspberries were variously combined with the dewberry. In the first generation of these hybrids, numer- ous red berries and black berries were produced, but no yellow ones. A large proportion of the red varieties followed the raspberry in general char- acteristics except in form, but some of them ac- quired the high flavor of the dewberry combined with the aroma of the raspberry. Most of the seedlings of this first generation [60] <» 3 *s a a. LUTHER BURBANK resemble the wild dewberry in habit of trailing along the ground. Yet there were some that fa- vored the raspberry, standing upright. In flavor many were a good combination of the two par- ents, but the variation was pronounced in this respect. Some were highly flavored while others were quite insipid, and between the two were all gradations. Variations in size and shape were equally marked. Most of these seedlings were quite productive, but no one plant was sufficiently valuable to war- rant its introduction as a new variety worthy of cultivation. Berries were gathered, however, from the most promising of the dewberry-raspberry hybrids. Among the second-generation seedlings thus pro- duced was one that was of different caliber from all the rest as shown by the character of its fruit. No such berries were perhaps ever seen before as those that grew on this second-generation off- spring of the Cuthbert raspberry and the Cali- fornia dewberry. Some of the berries were an inch and a half long and an inch in diameter. They were a dark rich crimson color, slightly downy, and glossy. In flavor they combined the qualities of raspberry and blackberry, both flavors seeming to be in- tensified. In a word the fruit was a blend be- [62] The Phenomenal Berry The color print shows this remarkable berry much reduced in size. Many of the berries are an inch and a half long and an inch in diameter. In flavor the Phenomenal berry combines the qualities of raspberry and blackberry, both flavors seeming to be intensified. Its individual qualities are so marked and distinctive that it is entitled to be designated a new species. LUTHER BURBANK tween the fruits of the parent races. It was a new variety so markedly distinct from either parent as to justify the designation of a new species. The new berry was originally called the Hum- boldt, but was subsequently rechristened the Phe- nomenal by the purchaser. The new fruit was not altogether unlike the Loganberry, which was an accidental hybrid dis- covered by Judge J. H. Logan on his place near Santa Cruz, which was believed to be a hybrid between the red raspberry and the California dewberry. But the Phenomenal is far superior in size, quality, color, and productivity, and it is gradually displacing the Loganberry. Unfortunately the two are sometimes con- founded, and unscrupulous dealers have been known to sell the Loganberry under the name Phenomenal. The new fruit, like most other plant develop- ments— the Burbank plum, the Wickson plum, and the Pineapple quince, for example — was not fully appreciated for about ten years. But it is now a standard berry on the Pacific Coast, and as far as possible it is being introduced in other re- gions wherever it will thrive. As already noted, it is probably the largest of all known berries. As a fruit for drying and canning it is of the first importance. [64] ON THE RASPBERRY From the standpoint of the plant developer the Phenomenal is of additional interest because of its almost exact combination or blend of the qualities of its parents. I have raised numerous seedlings from the Phenomenal, but up to the present have found none that quite equals it in all its excellent quali- ties, though, like the Primus, it is a fixed new spe- cies, the seedlings not reverting to either parent form. The new berry has also been used as seed parent in a number of crosses with other black- berries and raspberries. Some thousands of seedlings thus produced are now under observation. Among these hybrids great variations will of course, occur, and while nearly all will undoubt- edly be of inferior quality, I have confidently ex- pected to find at least one that surpasses even the Phenomenal; and now this expectation has been fully realized in a new sweet variety which will later be introduced. OTHER PERFECTLY BALANCED HYBRIDS Hybridizing experiments of almost equal in- terest, even if not quite so striking in results, have been made between the various raspberries and the Lawton blackberry. The Lawton is a very prepotent parent in these crosses, and its characteristics will almost invari- [65] LUTHER BURBANK ably be found to predominate. Even the pollen of the Lawton when applied to the raspberry more often produces the Lawton type of berry than any other type. But in exceptional instances I have produced Lawton hybrids in which the prepo- tency was not so strongly manifested. Such was the case, for example, with a cross between a yellow raspberry known as the Golden Queen and the Lawton. This produced a hybrid so well-balanced that no one who saw it could tell whether it was a raspberry or a blackberry. Numerous seedlings of this hybrid strain were raised, and in the second generation the qualities of the hybrid were reproduced, as in the case of the Primus berry and the Phenomenal. No vari- ation occurred such as is usual in the second gen- eration of most hybrid blackberries and rasp- berries. The bushes had prickles that were short and stout instead of long and slender as in the rasp- berry. The leaves also had the rough, ribbed ap- pearance of the blackberry. The berries would cling to the receptacle (a blackberry trait), or part from it (a raspberry trait), according to ripeness. As to color, there were both red and yellow varieties among the hy- brid plants. The flavor of the berries was not exceptional, but in some other similar crosses [66] ?fg LUTHER BURBANK made at a later period the fruit was in some cases greatly superior in quality to that of either of the parents. Still greater interest attaches, perhaps, to a hybridizing experiment in which the parents were Shaffer's Colossal raspberry and the Crystal White blackberry. Some of the plants from this cross were of the most tree-like proportions. Most of them, how- ever, were barren, though they bloomed freely. But there were exceptional ones that fruited, and selected seedlings were grown from these through a series of generations. In the fourth generation a plant appeared which was of such extraordi- nary characteristics that it was given the name of Paradox. This plant was in all respects a most perfect combination of the two ancestral forms from which it sprang. The wood, bark, leaves, blos- soms, prickles, roots, and seeds could not by any test be proved to be like one or the other. The fruit, produced in abundance, was an oval, light red berry of good size, larger than that of either progenitor, and of fair quality. Many of the first generation descendants of the Paradox were partially barren, though bloom- ing freely. Sterility as to fruit was often associ- ated with gigantic growth. [68] An Alaskan Raspberry This Alaskan berry has qualities that entitle it to consid- eration on its own behalf, at least in the region where i native. Mr. Burbank is using it in hybridizing experiments; and his success with the Siberian raspberry and other types of wild fruit leads him to think that interesting developments will result from the combination of the Alaskan berry with other races. LUTHER BURBANK But some of the seedlings were fertile, and they manifested almost every possible combina- tion of qualities of the raspberry and blackberry. Some were similar to the Paradox, except that they had white berries instead of red. By saving seeds from the white and the red varieties separately, I found that they bred true, each constituting practically a fixed species. As to the vines themselves, there is very little variation, the canes and foliage presenting an exact balance between the raspberry and the blackberry. The berries are not of great commercial value, as the fruit though large is soft. I hope, however, to harden the berry by selective breeding, and in- troduce a better flavor. Although this hybrid progeny of raspberry and white blackberry may ultimately have commer- cial importance, it is chiefly prized for the scien- tific significance of its revelations. Descended as it is from a cross between the raspberry and the blackberry, it constitutes a fixed species differing radically from every other Ru- bus known. So in this regard the Paradox takes its place besides the Primus and the Phenomenal berries as offering an impressive object lesson in the pro- duction of new species by hybridization. Let it [70] LUTHER BURBANK be recalled, however, that the Primus was a first generation hybrid, whereas the Phenomenal ap- peared in the second generation, and the Paradox in the fourth. There has been occasion in an earlier chapter to tell of hybridizing experiments in some re- spects even more curious, in which the raspberry was fertilized with pollen of the strawberry. These experiments will be further examined in a later chapter, with reference to the interpretation of the observed phenomena of hybridization of the various brambles. But perhaps no comment could greatly add to the impressiveness of the simple recital of facts as to the production of new forms that, according to all botanical standards, should rank as distinct fixed species, through the purposeful blending, under the hand of the plant developer, of the ger- minal strains of the various blackberries and raspberries. — The chances of obtaining results in plant improvement are directly proportionate to the number of experiments tried; and a hundred thousand experiments may be con- ducted as simply as a few. 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 illustra- tion 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 [VOLUME VI— CHAPTER III] LUTHER BURBANK 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 cor- ners, 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 charac- terization. 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 cus- [74] BM *3?sss-3.!rs3s- s?i- srs-s. |f2*§!i&3 * HF* BBS SassSs a a • ^J 3.||g|||s^||| jja § . sISS* cS o HJifl 1 LUTHER BURBANK toms 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, al- though even here there is no very wide diversity. But as to fruit, every strawberry of whatever species may be instantly recognized as a straw- berry 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 necta- [76] ON THE STRAWBERRY rines, apricots and plums, apples and quinces, oranges and grape fruit, lemons and limes, black- berries and raspberries, watermelons and musk- melons — these and sundry other fruits seem to go in pairs, as it were. They show the result of Na- ture'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 stand- point 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. [77] LUTHER BURBANK Aforetime it placed the seeds on the very out- side, 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 straw- berries might spread and inhabit the earth. The plant that cowers close to the ground can- not 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 precau- tion 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 re- tained. There are a good many scores of them [78] Hybrid Strawberries These hybrid strawberries show the influence of wild pro- genitors in the form of the fruit. But all varieties of straw- berries, and for that matter all species, are of remarkably uniform structure. No one could mistake a strawberry of any variety for a fruit of any other race. LUTHER BURBANK 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, de- voting 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 hith- erto the plant developer has been concerned to increase the fruit itself and has given small thought to the seeds or has ignored them alto- gether. But the briefest inspection of different straw- berries 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 root- ing stalks or runners tend to lose their power of seed production when long cultivated. The pine- [80] ON THE STRAWBERRY apple, the banana, the sugar cane, the horse- radish, 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 condi- tions 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 writh 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 [81] LUTHER BURBANK improve a plant slightly by selection when propa- gated 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 in- troduction 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 desir- able 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, notwith- standing the verdict of the enthusiast already quoted. But, on the other hand, it must be ad- mitted that the best varieties of fruit approach an ideal standard rather closely. And when we recall that the development of these almost perfect vari- eties has taken place very rapidly and within com- paratively 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 under- take the task of eliminating the seeds from the strawberry need not hesitate for fear of succeed- [82] I ^a~ H.r li So «*" ^ 5 2 5? '§? r*8l58Sasr|| ll^rslili*!'" £"BB§IS82l'e§&. ^Is^so-Si^lS.s-g o.^s^.ft^os-soa ?«B?3S5;a??- o« 2 o' Vs LUTHER BURBANK ing 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 mod- ern varieties have been developed in a period of not more than two centuries. The strawberry has indeed been under cultiva- tion 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 contury from Chili. Nor indeed was there any immediate improve- ment from the introduction of this fruit. But [84] ~itjp !*JI«**?l'r LUTHER BURBANK about the year 1760 a new variety suddenly ap- peared that was called the Pine strawberry be- cause 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 Fra- garia 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 straw- berries 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 selec- [86] s - *«. ^2 H Ji j^g ^5 P **^ ** *•* *^ 53 *• o ** ii i?n*i ?55<§usio **%** s 2! 3'^s'^x ^ as** ^ o- rb •^ S; s1 S tu o 2 o w 2 6-S • *i 2 <* ••• 3!^I S. ^ LUTHER BURBANK tion. Of curse, many varieties, differing in such minor details as the production of runners, resist- ance 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 Cal- ifornia 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, al- though 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 varie- ties, and in addition have made hybridizing ex- periments 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 straw- berry with those of strawberries from Norway and from Alaska, and the native Chilian species, as well as with various wild species of our own. [88] !H 1 • — . * S W . . *^ ir ft ** ^ ™ LUTHER BURBANK I have also attempted to hybridize a species from India, the Fragaria Indica, with other straw- berries, but have been unsuccessful. It does not by any means follow that this cross cannot be ef- fected. But it is perhaps not worth while to de- vote 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 pos- sibilities of hybridization. It is rather interest- ing 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 culti- vated 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. [90] LUTHER BURBANK 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 gath- ering. This plant also varies widely in different locali- ties. 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 [92] A Stage of Development In the course of his experiments, Mr. Burbank has worked extensively with several species of California strawberries. These show a very wide range of variation, growing in different ter- ritories, and give good opportunity for selection. As might be expected, combinations between these wildlings and the cultivated varieties often show great vigor of growth, and give the plant-developer the oppor- tunity he is seeking. LUTHER BURBANK 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 cur- rants, 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 [94] -**?m*3J, s> •se"s.iss"gs II °^a MtSpibi ** £. -«"s:.5?»&f5a slir!i;t:!!S eg S. «s6?si • .r-s"5 ^i:is.|3 ii«r fJ-O g LUTHER BURBANK 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 de- sirable characteristic of persistent bearing. The new strawberry has been developed through hybridizing stock that had among its ancestors such well known varieties as Long- worth'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. [96] >•**€$ JaB a o 5* ;» «c •» a* <* § S- <* rijfa » *« ft e a S-O-'I*:? 5.§ g LUTHER BURBANK inches above the ground, never growing upright. The foliage of the plant is pubescent or downy, accounting for its scientific name. In this regard also it is quite different from Solanum nigrum and Solanum guinense. The fruit grows in clusters of five berries that droop characteristically and always remain green- ish in color even when ripe, whereas the fruit of most other Solanums turns black on maturing. The berries are borne abundantly, and like the tissues of the plant itself they are free from poison- ous qualities. The wholesome nature of the plant is attested by the fact that it is eaten freely by herbivorous animals wherever it grows. Rabbits, cattle, and pigs eat it with avidity. PRODUCING THE SUNBERRY I have already referred to the long series of fertilizing experiments through which I endeav- ored to cross the various Solanums. I may add that Professor Hansen, of North Dakota, has also been interested in crossing the two fruiting Solanums of which we are speaking, and from which the Sunberry was ultimately pro- duced. But his efforts at hybridizing these species were unsuccessful. These details are mentioned to emphasize the fact that the production of the Sunberry — al- though, as will appear in a moment, it came about [118] ON THE SUNBERRY ultimately as the result of a single successful ex- periment— was by no means a task to be accom- plished offhand by the first person who chose to place pollen of one flower on the pistil of the other. I did this season after season, seemingly with no effect whatever. At last, however, in the season of 1905, after I had more than once half decided to relinquish the effort to hybridize these plants, my persever- ance was rewarded. I had cross-pollenized the great African stubble-berry, Solarium guinense, and the little downy nightshade, Solarium villosum, as I had done many times before, with no change or added detail of method, and for the moment I had no reason to suppose that the efforts had been more successful than before. But when the seeds were sprouted in the green- house, a certain number of plants were discovered that differed from any I had seen before. These plants were of a new type, and as they developed it became increasingly clear that they represented almost an exact compromise between the two parent species. There could be no question that they were the hybrids I was seeking. But the appearance of these hybrids was such as to corroborate the belief, founded on my long [119] LUTHER BURBANK series of unsuccessful hybridizing experiments, that the two Solanums I had finally mated were so widely different in constitution as to stand at the very limits of affinity within which crossbreed- ing is possible. We have discussed a number of instances in which similar crosses have been made between species widely separated. Such, for example, was the cross between the California dewberry and the Siberian raspberry, which produced the Primus berry; also that between the dewberry and the Cuthbert raspberry, which produced the Phenom- enal berry; and that between the plum and the apricot, which produced the Plumcot. In each of these cases, it will be recalled, the hybrid showing intermediate characteristics be- tween its parents, constituting virtually a new species, and proving its individuality by breeding true to type from the seed. It was rather to be expected, then, that the hybrid Solarium would similarly prove its individ- uality, and the expectation was fully realized. As the plants came to maturity, one bloomed but failed to produce fruit. The others, however, fruited quite abundantly, some of them profusely. The fruit was intermediate in size between the fruits of the parent plants. Its quality was en- tirely different from that of either parent. It had [120] A Relative of the Sanberry These are blossoms of a South American plant, the So- lanum jasminoides, sometimes called the potato plant. The blossoms of this plant closely resemble those of the sunberry, al- though the plants are very far from identical in other regards. The relationship between the two is not very close, but the similarity of blossom gives another illustration of the way in which a character may be trans- mitted and modified into different strains of plants from a dif- ferent ancestor. LUTHER BURBANK something of the flavor of the blueberry or huck- leberry of the East, and was especially delicious when cooked. It differed as widely as possible from the vile- tasting fruit of one parent and from the insipid, tasteless fruit of the other. It should be explained that there were only about twenty of these hybrid plants in a large colony of seedlings. The remaining members of the company were precisely similar to the mother plant on which they grew — this being the small, downy species, Solatium villosum — thus showing that they were not hybrids. It is probable that there was only a single fruit that had been hybri- dized, although the foreign pollen had been applied to many pistils. The entire company of new hybrid Solanums were probably produced from the seeds of a single berry, the other berries having been quite unaf- fected by the attempt at cross-pollenizing. But it sufficed to have produced a score or so of hybrids; I should have been delighted with a single one, after all these years of waiting. NEW SPECIES Naturally I selected the best two or three indi- viduals among the twenty hybrids — the ones ex- celling as to profusion, size, and flavor of berries. The seeds of these plants were carefully saved, [122] ON THE SUNBERRY and next season there grew from them a crop of plants precisely like the parents. The progeny of the hybrids followed their parents more closely than the unhybridized offspring of either of the Solanums used in the original cross usually do. As already noted, all species of wild Solanums tend to vary, but the new species reproduced itself exactly, except that a very slight difference in the flavor of the berries was barely perceptible. As two crops of these plants could be raised in a season, they were multiplied rapidly, and there was astonishingly little variation in the size, qual- ity, or growth of the bushes. Without exception the plants resembled the original hybrid, and differed radically from either parent of that hybrid. It was obvious, therefore, that a new and fixed species of Solatium had been evolved through the hybridizing experiment. As the reader already knows, the new plant was christened the Sun- berry. The unwarranted change of the name from Sunberry, the only name I ever authorized or approved for the plant, to "Wonderberry", and the mis-statements that have gained currency re- garding the origin of the plant and the character- istics of its fruit have been sufficiently referred to. The true qualities of the fruit itself have also [123] LUTHER BURBANK been revealed through a quotation from one of the many amateur gardeners who have grown it in successive seasons and found it a valuable addi- tion to the list of garden fruits. It may be added, however, that the Sunberry makes particular appeal because it ripens late in the season, after most other berries have ceased to bear. It is well to note, also, that the plant shows the hardiness and thrift and vitality usual with hybrids, and will often grow to better ad- vantage on a poor soil and without much cultiva- tion than when especial attention is given it. In most regions, to water it is a mistake, and to fer- tilize the soil for it an even greater one — making the blossoms drop. In a word, it is a plant that resents too much petting. It retains something of the character of its wild ancestors. As to inherent constitution, the Sunberry is a perennial, but it may best be grown annually from seed, quite as its relative the tomato is grown, although that plant also can live from year to year in the proper climate. As already stated, it grows true from seed year after year, proving thus its specific individuality, and differing not alone from hybrids in general but from the greater number of our cultivated fruits. [124] LUTHER BURBANK The Sunberry has unexpectedly been found adapted to cold northern climates. In the Alberta country, in the latitude of northern Alaska, the Sunberry is highly appreciated, especially as it is about the only berry that can be raised where the thermometer often goes to 40 or even to 60 de- grees below zero. VARYING TRAITS OF HYBRIDS From the standpoint of the gardener, the Sun- berry has importance as a notable addition to the list of small fruits. From the standpoint of the plant developer it may be said to have perhaps greater importance as illustrating the possibilities of the development of new species by hybridization — species markedly different from, and in many ways superior to, those from which they spring. It is true that other experiments have been detailed that illustrate the production of new forms of plant life through hybridizing already existing ones. A few paragraphs back several of these were named — the Primus berry, the Phenom- enal berry, and the Plumcot. But in the case of these fruits, it will be recalled, the parent forms were one or both bearers of valuable fruits. The hybrid plants improved upon their parents, but did not show entire departure from the traditions of the races from which they sprang. [126] ON THE SUNBERRY But the Sunberry, as we have seen, sprang from parent forms neither of which produced edible fruit. This was a union of two racial forms that were separated almost to the point of permanent seg- regation. The combination of hereditary factors of two distinct species from two hemispheres de- veloped a hybrid that differed very widely from either parent. As it chanced, this hybrid had qualities of fruit that gave it a new appeal and a standing, from the viewpoint of man, quite dif- ferent from that accorded either of its parents. The case, then, of the Sunberry emphasizes anew the principle that new species may be pro- duced through hybridization, and that, provided the parents are genetically separated just widely enough, their offspring may show such a blending of characters as to constitute a new form, and to be able to transmit these characters to its progeny in such a way as to meet the test by which species are everywhere recognized. We have seen that there is possibility of hy- bridization between forms that are a shade more widely separated, in which case the hybrid off- spring have the appearance of new species, but lack fertility. Such instances were presented in the hybrid colony of offspring of the dewberry fertilized by pollen from the apple and pear and [127] LUTHER BURBANK mountain-ash and rose; also by the hybrid be- tween strawberry and raspberry. These strange hybrids would clearly enough have been entitled to recognition as new species had they been able to reproduce themselves. But their sterility reduced them to the rank of mules — to make comparison with the most familiar in- stance of an infertile hybrid in the animal world. From these sterile hybrids the Sunberry dif- fers fundamentally in that it is if anything more prolific than either of its parents. Meantime the Sunberry differs from the hy- brids of another and more familiar type that arise from the union of parents that are so closely re- lated that cross-pollenizing is easily effected be- tween them. Such hybrids, of which we have seen many examples — crosses between the different daisies, between black and white blackberries, thorny and thornless briers, stone-seed and stone- less plums, and sundry others — follow, as we know, a characteristic line of development. The hybrids of the first generation resemble one parent more than the other. The hybrids of the second generation show wide variation, some of them re- verting to one ancestral strain and some to the other, the characteristics of each strain being vari- ously segregated and recombined. Nothing like the direct and complete reproduc- [128] A Brazilian Solanum This distant relative of the sunberrg — related also to the potato and the tomato — has been sent to Mr. Bur bank from South America, in the hope that its thorn might be removed. It is now undergoing training in Mr. Burbank's garden at Santa Rosa. Note the web-like effect of the leaves in relation to the main stalk and the smaller stems. LUTHER BURBANK tion of the characteristics of the hybrid in its off- spring, as shown by the Sunberry, is manifested in the case of these familiar hybrid forms that spring from the union of closely related species or varieties. WHAT THE SUNBERRY TEACHES All this should be borne in mind by anyone who is prone to reduce the principles of heredity to formulae of undue simplicity. The new formulae of the Mendelians, for ex- ample, which have such admirable application to many cases of the crossing of related forms — where particular unit characters are segregated and recombined — have no application, or to be applied must be distorted from their original im- plications, in dealing with such a case as that of the Sunberry. Here there is no clear balancing of dominant and recessive factors, with the overwhelming presentation of the dominant factor in the first generation and the reappearance of the recessive factor, beautifully segregated, in the second. Instances of inheritance of that order we have had presented again and again. We shall hear of more of them before we are through. But, in the meantime, let us not forget the lesson taught by the Sunberry — let us recognize that there are conditions of hybridization under [130] «*•••»•« •«•«.*» ;.. — vi 1 &• O* O* :inf!KliUi! ,si' :.gi|-a- Is-" ? |S^ "s?b 1 Sif-i 3" °-»-=-' =.§, ihiiiptfir'i |^s5' I*;?3* pM c 3 s a. 2 ^ a. g « * & "* c- 2ft<«^~ s.«%2-5 ^ ** 3 c^srS^so^sSca >.? o5=-.(^^3ScS«>^sl^.O ^iSHii81!'!^- B?25**'o3- §• ^^ -»«=•""» 2 a « a °*"> M. •H*l?I"iliw ..ill? I?5 *8 • •og.l 1111s § ? S" trCO'-^^ijD *^ X<***™ "S-V?ft?2^s-?-^?JS. I5-P3 S] LUTHER BURBANK which characters appear to be permanently blended when first brought together; not momen- tarily linked in an unequal union to be segregated in the next generation, but fixed in a new and lasting combination that strikes a balance between the combinations presented by the parent forms. It is possible, to be sure, to interpret this aspect of heredity in Mendelian terms. Nor should we deny altogether the validity of such application, for we may well believe that there are gradations all along the line, could we search them out, be- tween the case of the sterile hybrid, born of widely diverged parents, and the case of offspring of members of the same species that differ only as to some varietal character. Of course the same laws, could we fathom them in their broader aspect, apply to each and every case. But, on the other hand, it is at least open to question whether it would not be better to reserve the application of the Mendelian terms to such types of inheritance as Mendel himself studied, in which there was interplay of dominant and re- cessive factors, and the varied segregation of the different factors in new combination in the second filial generation. Thus restricted, the Mendelian formula has in- dividuality and specific meaning. [132] ON THE SUNBERRY There is danger that it may lose such individ- uality and such specific meaning, and with these a large measure of its real value and importance, if the propensity of some present day enthusiasts to make the words Mendelism and Heredity synonymous is generally followed. Be all that as it may, at least we hazard nothing in saying that the case of the hybrid Sunberry, sprung at a bound into existence as a full-fledged species, is of compelling interest to the student of heredity, from whatever aspect he may view the subject. — Whatever else may be said of the Sunberry, for or against, the fact remains that it was a successful union of two racial forms that were separated al- most to the point of perma- nent segregation. The Utah Currant The familiar cultivated currant is the descendant of a wild species that was found in both Europe and America. A good many other species are found in various parts of the world, and Mr. Burbank has utilized several in crossbreeding experi- ments. Among these is the Utah currant, here shown, a native of Western America. A DOZEN OTHER DELIGHTFUL BERRIES OFFERING ENCOURAGEMENT TO COMBINE AND BUILD IX the ensuing chapter will be brought together for brief consideration the records of in- vestigations having to do with a varied com- pany of berries, some of them among our most familiar garden fruits, others practically unknown to anyone but the specialist. It must not be inferred that these berries lack importance because they are grouped here to- gether instead of being given individual chapters. It is only necessary to name the currant, the gooseberry, the huckleberry and blueberry, and the cranberry as members of the list to give assur- ance that the fruits under consideration have con- siderable economic importance. But it chances that my work with these fruits, and the others listed with them for present consideration, has been somewhat less extensive than with the small fruits already described. [VOLUME VI — CHAPTER V] LUTHER BURBANK So much remains to be told concerning the plants with which more notable developments have been achieved, that it seems best to conserve space by treating the fruits that are now under consideration somewhat summarily. It will appear, however, that the amount of work done in connection with these various fruits is by no means inconsiderable; and that in more than one instance results have been attained that would warrant more extended consideration were it not that they must be viewed in a relative scale. Let us then somewhat briefly run over the list of a number of interesting fruits that fully justify the title under which they are classified in the present chapter, yet which have associated with them no story quite so spectacular as some others that have been reviewed in recent pages. We may first recall a few less conspicuous members of the great Rubus family — the bram- bles. The more notable members of this remark- able family have been dealt with at length. But we cannot take leave of so notable a group without at least incidental reference to a few other mem- bers of the tribe that have shown interesting pos- sibilities of development. One of the most interesting among these minor Rubuses is the western raspberry, a wild black species, known to the botanist as Rubus leucoder- [136] Wild Oregon Currant This is another of the wild species of currant growing along the Pacific Coast, and one that gives promise of value as a hybridizing agent. Even in the wild state, as here shown, it bears fruit of a good size, and of fair quality. LUTHER BURBANK mis. This plant, as its Latin name suggests, has a white stem. As to fruit, it rather closely resem- bles the eastern black raspberry which is a parent of our cultivated blackcap. It is a strong, vigorous grower, producing stout upright canes and berries that are unusually sweet and of a pleasing flavor. Several years ago, while in the Eel River region in Humboldt County in California, I discovered many excellent plants of this western blackcap of specially vigorous growth, and producing berries of extra size and quality. A large number of berries were gathered from the most promising plants, and their seeds carefully planted. After several years of planting and selecting, a promising berry was produced, fully as good, I think, as most eastern blackcaps and much larger than any then known. Unfortunately, the stem and backs of the leaves of the plant are covered with long, sharp prickles, and these are so an- noying in cultivating or picking the fruit that it seems not worth while to introduce a plant thus handicapped. There is opportunity, however, to do away with these prickles through hybridizing and selective breeding along the lines already fully detailed in the account of the thornless blackberry in an earlier chapter of the present volume. When this has been done, the developed variety of the west- [138] ON SOME ODD BERRIES era blackcap will be worthy of a place in the small-fruit garden side by side with the very best varieties of raspberry under cultivation. It should be added that this species, like a number of the eastern Rubuses occasionally pro- duces nearly white berries. These also might be developed into fruits of real merit, and doubtless will be when someone finds the time and interest to carry out the experiment of developing them along the now familiar lines outlined herein. THE GAPE RASPBERRY One of the strangest forms of Rubus with which I have experimented is a species that came to me from New Zealand but which had its origi- nal home in Southern Africa. This form is known as Rubus capensis, in rec- ognition, presumably, of its having been found in the Cape region of Southern Africa. It is not confined to this region, however, as it is believed to be the same species described by Stanley as growing in various regions in the heart of the Dark Continent. The fruit borne by the Cape raspberry is of a dark mulberry color. It is of the raspberry type quite unmistakably but is larger than any other raspberry I have ever seen. The quality of the fruit is fair, and its large size makes it peculiarly attractive. [139] LUTHER BURBANK The foliage of the plant is peculiar, having a curious resemblance to leaves of the grape. In- deed the resemblance is so striking that people passing it at a little distance have often asked what kind of a grape I had that grew upright like a bush. The entire plant is highly ornamental, growing about four feet in height and bearing its hand- some, large, leathery leaves in profusion. The prickles on the leaves grow so close together and are of such texture that they scarcely injure the skin in handling them. The plant is not very hardy, but its other quali- ties make it a very desirable species for hybridiz- ing experiments. Indeed, I know of no wild species of Rubus in the world that gives more promise of being useful. My own experiments with the plant were not carried far enough to produce particularly notable results. But the plant invites attention from anyone who is inter- ested in the further development of our small fruits. Coming from the Southern Hemisphere, it should introduce a tendency to variability in a conspicuous degree when crossed with some of our northern species. Among other good qualities of the hybrid progeny, there should be a tendency to prolonged bearing, such as we have seen in the case of the [140] South American Currants Attention has been called repeatedly to the large use that Mr. Burbank makes of the South American plants in his hybridizing experiments. The currant furnishes still another illus- tration. It is fruit that is of no great value in itself, but no one can predict what possibilities it may reveal when hybridized. LUTHER BURBANK strawberry produced by the crossing of species from the two hemispheres. THE SALMON BERRY Another very interesting Rubus that shows great possibility of development is the native species familiar along the Pacific Coast from Cen- tral California to Alaska known as the Salmon berry, Rubus spectabilis. This is a tall, erect bush, with stout, perennial canes. The stalks are usually sparsely clothed with weak, slender prickles, but are sometimes nearly smooth. The flowers are borne singly and in pairs on slender stalks; they are large and showy, being bright red or purple. In Humboldt and Mendocino Counties, Califor- nia, I have seen this berry growing in the pastures where it became a genuine tree from twelve to fifteen feet in height, some of the stalks being two or three inches thick. It is reported sometimes to grow six inches in diameter. The cattle in the pastures browse on the plants as high as they can reach, and the berries are gathered with a step- ladder or more commonly from the back of a horse. The berries themselves are large and soft, al- most falling to pieces in the picking. They are unusually juicy, and with almost no acidity. There are two strongly marked varieties of [142] Fruit of the Flowering Currant There are several species of currant, that, owing to their rather exceptional flowers, are popularly designated as "flower- ing currants." Some of these grow wild in the Rocky Mountain regions, others along the Pacific Slope. In the wild species, the fruit is usually not of a high order, but in one case at least this has proved capable of great development through selective breeding. In general, the wild cur- rants are worthy of more attention than they receive fiom the fruit developer. LUTHER BURBANK Salmon berry. One has the pale yellow fruit, the other reddish, varying to dark crimson. These two varieties may be seen growing side by side, in some instances without intermingling, each in- dividual bush producing berries of one distinct quality and color. The Salmon berry requires a damp, cool atmos- phere and moist soil. When transplanted into the warm valleys it does not thrive. There chances to be a moist piece of sandy land on my Sebasto- pol farm, however, where it thrives fairly well. Here we have grown the Salmon berries from Alaska, Washington, Oregon, Northern Minnesota, and various parts of northern and central Cali- fornia for more than twenty years. Among these I have noticed considerable varia- tion in the size and color of both fruit and flowers. My experiments, however, have not been carried out extensively, partly because of the difficulty that attends the growing of the Salmon berry in this locality. But I have gone far enough to make me confident that the fruit is worthy of further devel- opment, although I shall probably leave the task for someone who is more favorably situated geo- graphically for the cultivation of this particular fruit. THE JAPANESE GOLDEN MAYBERRY We have already learned that the Rubuses are [144] Fruit of the May berry The Mayberry came to Mr. Burbank as a wild plant from Japan, bearing a fruit of small value. It proved responsive to the plant-developer's effoil;. and ultimately developed a fruit that was christened the Japanese Golden Mayberry. LUTHER BURBANK cosmopolites. The facility with which the seeds of the bramble berries of various kinds are dis- tributed by the birds doubtless accounts in part at least for the wide migrations of the tribe, and this in turn accounts for the great range of variation among the different species. In the course of my experiments with the fam- ily, I naturally enough looked to Japan to supply material, just as in the case of so many other tribes of plants. The species that I received from there certainly did not appear to be an encouraging plant to work upon. Yet it proved susceptible of development, and well repaid the efforts bestowed upon it. The plant in question was found growing wild high up on the sides of Mt. Fujiyama in Japan. It is known botanically as the Rubus palmatus. The collector who secured it for me sent the best specimens of the fruit that he could find, and roots of the plant itself. The plants that grew from these roots bore large, white blossoms, solitary and drooping on long, slender stems swinging from the leaf axils. But the berries were a great disappointment, being small and of a dingy, yellowish, unappetiz- ing brown color. Their flavor was as unattractive as their appearance. [146] Canes of the Mayberry The Japanese Mayberry is still undergoing development in Mr. Burbank's garden. Among other things, an attempt is being made to remove the thorns from the stems. Partial success has been attained, as these pictures illustrate. The tendency to variation here shown suggests indefinite possibilities of further improvement. LUTHER BURBANK Knowing the possibilities that lie in the hybridization of Oriental species with their Ameri- can relatives, however, I did not despair of the Mayberry, but hybridized it with the Cuthbert raspberry, a plant that proved a remarkable parent, as will be recalled, in connection with other hybridizing experiments — notably the production of the Phenomenal berry. The hybridization was effected without diffi- culty, and the progeny showed a tendency to rapid improvement. After a few generations, the berries were greatly enlarged, and took on a bright yellow color instead of the original dingy brown. The improvement in quality was also very appreciable. But what was perhaps most notable was the extreme earliness with which the hybrid plants fruited. It was, indeed, the early bearing habit of this Rubus that stimulated me to make the cross. It proved possible to retain and accentuate this habit while introducing the Cuthbert quality into the berries. The result was a new type of berry, as large as the Cuthbert raspberry, ripening in April, a month before the Hansell, a variety then famed for its early fruiting. Indeed the hybrid Rubus bears fruit at a time when the earliest of the standard raspberries have hardly awakened from their winter rest. This habit of early bearing combined with the [148] ON SOME ODD BERRIES unusual qualities of the berry itself seemed to justify its introduction. So it was announced to the public in 1893 as the Japanese Golden May- berry. The bushes on which the Mayberry grows are distinct from all others of the tribe, attaining a height of six or eight feet and being almost tree- like in form. All along the branches the white, bell-shaped blossoms are pendant, soon succeeded by the large, sweet, golden, semi-translucent berries. The plants do not at first bear very heavily, but as they advance in age they produce a sur- prising abundance of fruit. Unfortunately the hybrid Mayberry is not hardy, and so is not adapted to the climate in many parts of the United States. It has become almost the standard berry in the Philippine Islands, and it is sure to gain popularity in any climate to which it is adapted. More recently I have given attention to improv- ing the variety, and the developed races bear lus- cious fruit fully an inch and a half in diameter. The fruit is rather soft and more suitable for home use than for the market. But it is a productive and delicious berry, well worthy of introduction in all milder climates. Possibly a series of hybridizing experiments, [149] LUTHER BURBANK introducing some northern species of Rubus, would result in giving the plant hardiness, in which case it should become popular everywhere. Such a line of experiment is well worth undertaking. THE CLOUDBERRY In marked contrast to the Mayberry in point of habitat and hardiness is the Rubus from the far North that is commonly known as the Cloudberry, or, in some regions, the bake-apple berry, and known to the botanist as the Rubus chamemorus, a name given to it more than a century and a half ago by Linnaeus. The plant inhabits the peat bogs and similar localities far to the North, even within the Arctic Circle. Like many other arctic species of plants it does not confine its habitat to a single continent but is found in northern Europe and Asia as well as in North America. The same thing is true of Arctic species of birds and animals; the obvious explanation being that it is easy to wander from one longitude to another in the regions where all longitudes merge toward a common center. On this continent the Cloudberry extends southward along the mountain ranges to Maine, on the east coast, and on the west coast to South British Columbia. The plant bears berries of the characteristic Rubus type that are more commonly flattened [150] Squaw Berry The Squaw Berrg or partridge berry, known to the bot- anist as Mitchella repens, is a hardy perennial. Its berries are edible, but quite lacking in flavor. It may be expected, how- ever, that they can be much improved through selective breeding. LUTHER BURBANK raspberry-shape or nearly globular, of a bright red or yellowish color, and of a pleasing acid flavor. They are highly prized in all northern countries, being among the best fruiting Rubuses of Norway, Sweden, and Alaska and Labrador in America. It was my good fortune while in Alberta, along the North Fork of the Saskatchewan River, to see this interesting northern species growing wild. The plants with their small, slender, trailing branches and rounded or almost heart-shaped leaves, were very attractive. Some of the seeds were procured for cultivation. The seeds germinated perfectly and vigorous plants developed. But, although they were placed in as damp and cold a spot as could be found on my grounds, they did not thrive in the warm, dry atmosphere of a sunny California summer. The change from the northern habitat was too great, and, although the plants lived for a year or two, no important developmental experiments were made with them. They so obviously found the conditions uncon- genial that it was thought best, after a year or two, to discontinue the attempt to reconcile them to the change. Whoever considers the production of hardy varieties of raspberries, however, should bear the [152] ON SOME ODD BERRIES Cloudberry in mind. It offers obvious possibili- ties as a hybridizing agent to give hardiness of the most "ironclad" kind to a variety that may lack that essential quality. Possibly the Japanese Mayberry will ultimate- ly be made adaptable to northern climates by such an infusion of new blood. THE EVERGREEN BLACKBERRY As further illustrating the wide range of the bramble tribe, we may refer to a species that is indigenous to the South Sea Islands, whence it was introduced into this country and Europe so long ago that there is no clear record of its com- ing. Indeed, the precise place of its origin is somewhat in doubt. The species referred to is the Evergreen Black- berry, Rubus lacinietus. In our northwestern states, especially in western Oregon, this black- berry is cultivated extensively. It is popular as a home berry, since it produces fruit from midsum- mer until late autumn. As its name implies, this is an evergreen, or nearly evergreen plant. It is a trailing bush with thick perennial canes armed with very stout re- curved thorns. This blackberry was worked upon quite ex- tensively on my place in 1890, and the following years, at the time when my chief experiments in [153] LUTHER BURBANK the hybridizing of the Rubuses were at their height. Among the hybrids produced were some very curious forms, the variation in the shape of the leaves being especially remarkable. Some of the leaves resembled those of the grape, others were much dissected, like the leaves of a wild carrot. The most promising of the hybrids were pro- duced from a cross between the Evergreen and the popular Lawton blackberry. Some selected seedlings from this cross, in the second genera- tion, were rampant growers, thorny, with curious, handsome, palmate leaves and delicate pink blos- soms. The berries ripened late in the fall. Some were rather large and possessed a superior aro- matic sweet quality not found in the common summer varieties. One of these promising hybrids was mentioned in my New Creations in 1893. It was never intro- duced into cultivation, however, as its merits were not quite equal to those of some other riri- eties of different parentage. But there is no do< i>t in my mind that if the experiments with the Ever- green blackberry, of this or some other hybrid combination, were carried to a more advanced stage, really useful varieties would be obtained. THE COMMON CURRANT Notwithstanding the importance of the Rubus [154] SS-sS^g^aaS1* rllflPISifs* « o 5. JI a.r-« LUTHER BURBANK family, its members have by no means a monop- oly among the popular small fruits of the garden. There is at least one other bush that may claim to compete with the brambles in wide range of habitat and in general popularity among gar- deners. This, of course, is the familiar currant. The forebears of the currant grow wild, repre- sented by various species in both Europe and America. The wild red species, Ribes rubrum, from which all our common cultivated red, white, and pink currants, large and small, sweet and sour, are descended, is indigenous to both conti- nents. It has maintained its specific identity re- markably through long generations, as the close similarity of the specimens found wild in Europe and America testifies. The more common Amer- ican wild species, however, in most regions is the black currant, which also has a European con- gener. The American black currant is a hardy plant, growing far north in Canada. It varies greatly in different regions, both in appearance and in the quality of the fruit it bears. There are other wild species and varieties without number, so that there is abundant mate- rial supplied the plant developer for work with this valuable fruit. I have experimented with a large number of [156] ON SOME ODD BERRIES varieties from different regions, and have pro- duced some interesting anomalies. One of these was the result of hybridizing a native red species known as Ribes sang nine um. By selection and cultivation, varieties of this plant have been pro- duced on my ground that bore flowers of brilliant colors and the largest fruit, perhaps, ever seen on a currant bush. Most of the crosses of this species were made between a form collected on Vancouver Island, British Columbia, and the forms native to the regions about San Francisco. The Vancouver forms had long racemes of light crimson flowers and small bluish fruits. The coast form has larger fruits with a more resinous odor, the ber- ries varying in color from bluish to black. My efforts with these species were mostly directed toward increasing the size of the fruit. As just stated, the results are quite noteworthy. Bui the experiments are still under way and the ultimate possibilities of development are yet to be revealed. My experiments in hybridizing the currant have extended to all the species and varieties that I could obtain. At times I have had five thousand currant seedlings under observation. In addition to the European and American species, I have worked extensively on varieties [157] LUTHER BURBANK imported from Japan and China, and from north- ern Asia and Russia. I have also crossed the currant with the goose- berry, but the hybrids in this case produced no fruit. Notwithstanding the large number of ex- periments and their interesting results, I have not produced any new currant that was thought worthy of introduction. There is now under ob- servation, however, a hybrid seedling from the Calif ornian species already referred to — Ribes sanguineum, which is several generations removed from the original, and which bears long clusters of very large blue berries with few seeds. This is the best of thousands of hybrids that I have grown, though I have produced a few really good currants of unique form and flavor, as well as a flowering currant of unusual size and beauty. All in all, my work with the currants, while substantiating and emphasizing the principles of plant development that work with other plants had made familiar, and while showing many fea- tures of interest, has not resulted in any very striking developments; largely, perhaps, because attention was diverted from this line of work to other experiments of greater immediate promise; and because the experiments were too radical, taking in so many species that so many unique characters appeared that I had not time to segre- [158] The Balloon Berry An unfamiliar, but promising fruit with which Mr. Bur- bank has experimented extensively in recent years is the variety of Rubus, called the Balloon Berry, so named because of the shape of its fruit. It may be trained as an upright shrub, and its large white blossoms appear very early in the spring. LUTHER BURBANK gate them. If I had worked with a single species, more immediate commercial results might have been attained. Much of the work with currants was done for its aesthetic and scientific interest rather than for immediate commercial prospects. THE GOOSEBERRY The currant has a very close relative which vies with it in popularity, particularly in England —the familiar gooseberry. This plant, indeed, is in reality a currant that has developed or re- tained the habit of bearing prickles both on the stem and on the fruit itself. This is the practical distinction between the gooseberry and other varieties of currants. All the plants of this tribe belong to the same genus. There are some species in California that puzzle a botanist as to whether they should be classified as currants or gooseberries. In Europe, and particularly in England, the gooseberry has been cultivated with the greatest possible care and through selection the fruit has been brought to a very large size, superior qual- ity, and unusual productiveness. But unfortunately the thorns have never been eliminated, except in the case of one or two in- ferior varieties. These were offered several years ago by an English firm, but their quality of fruit was so inferior that they have not become popular. [160] Balloon Berry in Bearing This shows the balloon berry later in the season when in full bloom. It will be seen, however, that there are still blos- soms on the vine. The blossoms and fruit are shown in larger view in subsequent pictures. LUTHER BURBANK It has already been mentioned that I was able to hybridize the gooseberry and the currant. The cross is very difficult to make, however, and in my experience the hybrids were sterile. This sug- gested that the two plants, notwithstanding their affinities as judged from the standpoint of the botanist, have really diverged rather widely. But there are many species of gooseberry as well as of currant, and it would doubtless be possible to find varieties of the two plants that have closer affinity. The hybridizing of these would offer interesting possibilities. I have experimented extensively with the gooseberry, as with the currant, and have pro- duced a great number of gooseberries of superior quality; none, however, that were really notable. Some of my most interesting experiments had to do with the native species known as the Coast gooseberry, Ribes divarication, which grows around Tomales Bay. I have also worked with the Canyon goose- berry, Ribes menzieszi, a tall rapid-growing shrub with rather small leaves and very prickly stems. The berries of this variety resemble a chestnut burr rather than a gooseberry, the spines occupy- ing the whole surface of the fruit. The fruit itself is excellent in flavor and is prepared for eating by being placed in hot water so as to soften the [162] Flower and Fruit The balloon berries have an unusual habit of bearing flowers and fruit at the same time, as here illustrated. It will be seen that the flower is closely related to that of the blackberry. The fruit is also not unlike a blackberry except that it is almost globular in shape. LUTHER BURBANK prickles, after which the pulp is easily crushed out. I have developed several partially thornless varieties of this gooseberry, and have also had partially thornless ones sent me, showing that the species tends to vary. But the seedlings from these partially thornless plants always produced thorny varieties. It is probable, however, that further experiments might reveal specimens that would drop the thorns altogether and would breed true to thornlessness just as the thornless black- berries do. This, indeed, should be the aim of the plant developer in connection with all varieties of gooseberries. The plant offers a splendid oppor- tunity for hybridizing and careful selection. If it could be induced to shed its thorns and still bear large fine fruit, the gooseberry would gain enormously in popularity. At present there is a not unnatural prejudice against this fruit be- cause the thorns constitute an almost intolerable nuisance, their sting being peculiarly irritating. My own experiments were carried far enough to suggest the probability of the production of thornless varieties. As to fruit, several varieties were produced that I thought superior to any pre- viously seen. But I was not able to introduce them properly, and after keeping them several [164] The Stalk of the Balloon Berry The stalk of the balloon berry is very characteristic in form, being almost square. Like most other Rubuses, the bal- loon berry bears thorns, but the thorns are very small; probably they may be removed altogether by selective breeding. LUTHER BURBANK years the bushes were destroyed to make room for other plants of greater promise. Subsequently, however, I regretted this and now feel that these plants might have rewarded further experimental efforts had I been able to find time for them. Certainly the gooseberry is well worthy of greater attention, from some plant developer who works along modern lines, than it has hitherto received. THE HUCKLEBEERY AND CRANBERRY Another interesting tribe of plants supplies us with the familiar market fruits known as bilber- ries, huckleberries, blueberries, and cranberries. These berries are little grown in the garden, but remain even to this day products of the wild, although the bushes on which they grow may be taken under man's protection and given a cer- tain encouragement in woodland or swamp. The botanist classifies the various huckleber- ries and cranberries in the genus Vaccinium. There are widely scattered representatives of the tribe in both hemispheres. Most of them are branching shrubs or creeping vines. A large por- tion of them are vigorous shrubs like the blue- berry and huckleberry; whereas on the other hand the cranberry is a trailing evergreen. The varie- ties in the different species are so numerous as to tax the skill and patience of the botanist. [166] ON SOME ODD BERRIES The berries are produced in enormous quan- tities. A mass of blueberries in fruiting time may seem to spread a blue carpet throughout cleared woodlands and pastures. And as to the cran- berry, I recall that in my father's meadow where these plants grew, I used to see the men rake the berries off the vines instead of picking them by hand, so profusely were they clustered. A very interesting feature of the blueberry and cranberry pastures, which I observed even as a boy, was the great variation, sometimes within the same square rod of ground, not only in the size of the berries but in their shape and quality. From the same patch, some berries would be sweet and highly flavored, others insipid and al- most flavorless. But individual patches as a rule appeared to be developed from one original seed- ling which had suckered out in various directions just at the surface of the ground, the trailing branches rooting wherever they touched the earth. Individual groups of plants, sprung thus from one seedling, would usually show the same quali- ties of fruit. On my last visit to New England I selected from the old blueberry grounds some of the most productive plants, and transplanted them to the experiment farms at Sebastopol. It has often been stated that the blueberry [167] LUTHER BURBANK cannot be cultivated to advantage, because it ceases to produce much fruit when removed from the wild state. My experiments did not justify this belief, as the bushes brought from the east were if anything over-productive. I have never seen plants of any kind produce a greater quan- tity of fruit in proportion to the weight of the plant. During the ripening season the bushes seemed to be a solid mass of berries. This over-produc- tion of fruit greatly restricted the growth of the plants themselves. By way of comparison I one season removed all the fruit from a certain number of the bushes. Relieved of the burden of fruit production, these plants made a large growth, quite outstripping the others; and the second year they produced a splendid crop. I was convinced that under proper conditions the blueberry might become profitable under cultivation in California but had not time to follow up the matter, and all were presently destroyed. The same fate awaited a collection of huckle- berries, bilberries, and other blueberries of vari- ous kinds that I had gathered from British Amer- ica, Oregon, Washington, and even from Norway. More recently I have received an allied plant said to be of unusual value from the mountains of [168] Interesting Hybrid Berries Some of Mr. Burbank's most recent and interesting experi- ments have to do with new types of berries. The boxes here shown contain some second-generation seedlings of crosses between the Balloon Berry and the Hawaiian raspberry. There are also a number of straight seedlings, of both parents, indicating the range of a season's work, along a single line. LUTHER BURBANK Central Japan. No important results from the de- velopment of this plant have as yet materialized, however. The blueberry and huckleberry are extremely difficult to raise from seed. But if kept sufficiently moist this may be accomplished. Cranberry seedlings can be grown by washing out the seeds and sowing in a protected place or in damp sphagnum moss. The young seedlings can be transplanted like other fruiting plants, but the operation is rather delicate as with all other Vacciniums. The soil must always be virgin soil, and with hardly a trace of lime, as all Vacciniums prefer what is commonly called an acid soil. The cranberry, like most other members of the tribe, spreads by sending out runners. It can be propagated by cutting the vines into small pieces. The plant does not thrive in California except in some bogs of the northwestern part of the state. In regions to which it is adapted, however, the cranberry is a crop of considerable importance, and there appears to be a splendid opportunity for someone to conduct experiments for the de- velopment of better varieties. Mere selection from the existing varieties would probably accomplish much. And of course still further progress could be expected if the dif- [170] A Near View of the Hybrid These are second-generation hybrids of the Hawaiian raspberry and the Balloon Berry. They were raised in the sea- son of 1924, and have not yet come to bearing. Interesting results are expected. LUTHER BURBANK ferent varieties were hybridized. By such work the crop could without doubt sooner or later be doubled in quantity, the size of the berries in- creased, and their quality greatly improved. The most desirable characters for the plant developer to have in mind would be, first, quality of the fruit, next size and color. The vines them- selves could be improved, both as to manner of growth and abundant production. Here as with other berries it would perhaps be possible to eliminate the seed, and this would obviously be of great advantage. The cranberries differ less than plants that have been more under cultivation, but they nev- ertheless show enough of variation to give full opportunity for selective breeding; and of course the variation could be increased by hybridizing, as with other species. Two INTERESTING TREE FRUITS To conclude this survey of common fruits that beckon the plant developer yet which have been largely neglected, I must make brief reference to the berries of two plants that differ radically from the vines we have had under consideration inas- much as they are trees or large shrubs rather than bushes. The plants referred to are the Mulberry and the Elderberry. [172] Pure Bred and Hybrid Compared The front box shows second-generation hybrids of the Balloon Berry and Hawaiian raspberry, like those shown in the preceding picture. The box in the rear shows the Hawaiian rasp- berry unmodified. A comparison of the two types of leaves gives a good idea of the modification effected by hybridiza- tion. There is, of course, a considerable range of variation among the second-generation hybrids, giving opportunity for selection. LUTHER BURBANK The mulberry is a relative of the fig, and it bears abundantly a fruit that is distinctly sug- gestive of the blackberry in general appearance, but which has a characteristic flavor of its own. Although the fruit of the mulberry is not alto- gether neglected, yet in general the tree is raised to furnish food for the silk worm or for ornament rather than for its fruit. It is obviously difficult to gather a crop of berries distributed among the branches of tree, and this fact no doubt accounts in part at least for the failure of the mulberry to gain popularity as a fruit producer. It would be possible, however, to train the mul- berry tree to a lower and more spreading growth, as it is generally propagated by grafting after the manner of orchard fruits. Indeed, that is the best way to propagate the fruiting varieties of mulberry, as it cannot be depended on to breed true from the seed. In point of fact the fruit of several of the best cultivated varieties is alto- gether seedless. Reference has been made in another connec- tion to my experiments in hybridizing the mul- berry with its relative the fig. Notwithstanding the lack of success of these experiments, it seems possible that further experiments along the same line might lead to interesting, and perhaps to valuable, results. [174] ON SOME ODD BERRIES As to the other berry-producing tree just men- tioned, the elder, the possibilities of fruit devel- opment are even more inviting. The common European elder, Sambucus nigra, has developed into a number of handsome orna- mental varieties, most of which are offered by the American nurserymen. Our native eastern species, the Sambucus Canadensis, the commen elder of the eastern United States, has also developed sev- eral forms; and there is a California species, S. glauca, that shows a like tendency to variation, both as to size of tree and size and quality of fruit. The berries of the elder are borne in large clusters, sometimes in enormous profusion, so that the bushes fairly break under their weight The fruit is generally bluish black, with a very thick white bloom. A curious anomaly is sometimes shown by an- other European or Asiatic species, S. racemosa, a variety of which grows in various parts of north- ern California and northward along the Pacific coast. This sometimes makes a large, rambling, tree-like bush, and the singularity in question consists in the fact that some of the bushes bear berries of a brilliant yellow color and others red- dish purple or almost black berries. The bushes intermingle almost indiscrim- inately, yet there is no intermingling of the differ- [175] LUTHER BURBANK ent berries on the same bush. Each plant bears exclusively berries of one color or the other. I have experimented extensively in the im- provement of the berries of the different elders and these experiments are still under way. My experiments began with the planting of seeds of the Mexican elder, which bore berries of medium or small size and of black color. Some of the plants that grew from these seeds produced, much to my surprise, berries yellowish-white in color. Observing this tendency to variation, I at once surmised that improvements might be made in almost any direction with a plant that showed this tendency. So more seedlings were raised, and selection was made according to my usual method. From the best of these seedlings many plants were produced that bore berries of a yellowish white or sometimes grayish color. While the ber- ries were bitter, like elderberries in general, I noted that some were less bitter than others. Moreover, there was a diversity in size, and a great variation as to productivity. A few of the trees bore a constant crop all summer, blooming and bearing fruit throughout the season and well into winter. This was another unusual break in the tradi- [176] •i ci •f £ I ls-5.^ = 2. = 5-a^E53 g. § * S wSr^T-alaTSx LUTHER BURBANK tions of the family and one that seemed to offer pleasing possibilities. The experiment has continued along the lines of further crossing and selection. A few seasons ago I had from twenty-five to thirty thousand elder plants in bearing. From these the best, to the number of about seventy-five, were selected. And the trees of the generation now under obser- vation bear really delicious berries, without a trace of bitterness. Some are quite sweet, others acid. The best of them are an astonishing improve- ment over any elderberries I had ever seen be- fore. They make pies of excellent quality. The berries are grown in abundant clusters and they are individually of the size of small cur- rants. When dried they turn a light golden color, like the whitest of the white raisins. In flavor they can hardly be distinguished from the best raisins, though so notably different in size. The progress already attained makes it cer- tain that we shall soon be able to educate this elder to a condition that will make it highly ac- ceptable as a productive fruit, especially for arid regions. The elder grows readily from cuttings and will thrive in dry climates. I have under way also a series of hybridizing experiments in which the different elders, notably [178] ON SOME ODD BERRIES the progeny of the Mexican elder, and the Cali- fornia species already referred to, Sambacus clauga, and the hardy Dakota elders are com- bined. To produce still further variation and fa- cilitate progress, I have also crossed the new elder with species from Ariozna, one of which is a very large tree for an elder. From a second generation cross I got prob- ably one individual in forty that bore black ber- ries, but from the third generation not a single one out of several thousands was black. I se- cured, however, one that bore berries of a gray or mulberry color and two or three having a ten- dency to a mixed color. All the rest were white or amber. It will appear, then, that a race of elders has thus been produced that bears fruit of an attrac- tive white or amber color and of such quality as to commend it highly, as a substitute for other berries, in regions where the garden fruits in gen- eral do not thrive. Moreover, there is every prob- ability that the experiments now under way will result ultimately in the development of varieties of elder of such improved quality as to make a valuable addition to the orchard even in compe- tition with the most popular fruits. The elderberry has qualities of its own that will commend it strongly. If for no other reason, [179] LUTHER BURBANK the fact of its development on a tree or large shrub gives it peculiar attractiveness. The vine-like growth of many bearers of small fruit, notably the raspberries and blackberries, necessitates methods of cultivating, with perpetual pruning that many horticulturists find irksome. The elder shrub can take its place in the fruit orchard along with the trees that bear apples, or plums, or peaches, re- quiring no special treatment or attention, and constituting a permanent acquisition for the fruit grower. — There are opportunities in the by-paths of plant improve- ment, opportunities untold, which call out for patient specialized effort, and which will well repay the investment of that effort. GREAT OPPORTUNITIES IN THE GRAPE GENERATIONS OF GRAPE EXPERIMENTS HELP Us THE grape is the patrician among climbing plants as the strawberry is among trailers. The family to which it belongs is one of the smallest, as regards number of species, among plant tribes. But it is an oligarchy having very great distinction. What the membership lacks in numbers it makes up in quality. The grape is known everywhere and has been culti- vated by man from the earliest times. Doubtless as much attention has been given to it as to any other tribe of plants. Indeed it may be ques- tioned whether there is another that can compete with it in this regard. Of course the main reason for the extreme favor shown the grape by man has been all along the capacity of the plant to produce a fruit hav- ing a juice of unique quality that ferments readily to form a potable beverage. [VOLUME VI — CHAPTER VI] LUTHER BURBANK It is as a producer of wine rather than as a producer of fruit for the table that the vine has everywhere gained greatest popularity. Nevertheless the quality of its fruit is alto- gether noteworthy, and such as to give the plant distinction in the eyes of the horticulturist, even were it considered solely as a producer of table fruit. Moreover, there are certain kinds of grape that contain so high a sugar content that they dry without fermenting, constituting a third impor- tant commercial product — the raisin. All in all, then, it is easy to understand why the grape must be considered as a fruit standing in a class by itself, and having importance second to none. The manner of growth of the grape and the character of the clusters in which its fruit is borne are no less distinctive. No other fruit under cul- tivation in the least resembles the grape in either regard. And as to shape and appearance of the individual berries no less than in the matter of fragrance and flavor the grape manifests the same individuality. Different varieties show diversity of form and color and flavor, to be sure, but no grape of any variety is likely to be mistaken for a fruit of any other kind whatsoever. It is clear that we cannot attempt in the space at command to present anything like a compre- [182] s-^5., flM3£lS > Q. g c« -Q Ct sfa:*** -< •$*?* I 13 3^ t 2.C, ^ •3 B C M 2* i^ mi LUTHER BURBANK hensive story of the growth and development and world-conquest of this extraordinary fruit. Nor would it comport with the present purpose to do so. The main facts as to grape culture are mat- ter of common knowledge. Our concern must be with such features of habit, and constitution, and adaptability of the grape as particularly concern the plant developer, and have to do with the pos- sibilities of improvement. In particular, of course, here as elsewhere, we shall be concerned with a presentation of the work done at Santa Rosa and Sebastopol in con- nection with the development of this plant. This, as will appear presently, has looked chiefly to the improvement of the grape as a table fruit. I have not been concerned with varieties of the grape that are especially utilized by the maker of wine. These have been specialized to the point of approximate perfection in the great wine-growing districts, and it would be useless to experiment with them in any region except the one in which they are to be cultivated, because it is well-known that the grape takes directly from the particular soil in which it grows something of the unique qualities of flavor that determine the rank of any so-called good wine in the esti- mate of the connoisseur. It is only in two or three small districts of [184] Grapes of the Concord Type The familiar, and always popular Concord grape, has, naturally, been given attention by Mr. Burbank. He has pro- duced improved varieties of this grape by direct selection, without crossing, although he has also used the grape in his hybridizing experiments. LUTHER BURBANK France, for example, that grapes are grown from which the clarets can be made that are adjudged superlative in quality. It does not at all suffice to transplant cuttings of these vines to other regions. It would be nec- essary to transplant soil and climate also if the grapes are to retain their unique qualities of wine production. But the case of the grape considered as a table fruit is obviously different. Even though this also is doubtless influenced by the soil, the tests ap- plied to it are not of quite so refined a character, and the grape developed in one region may be expected to retain at least approximately its unique flavor when grown in another climate. So I have striven to develop varieties that would have commendable qualities of fruit and such qualities of hardiness of vine and prolific bearing as would make them suited to cultivation throughout wide territories. Here as elsewhere I have had in mind the needs of horticulturists not in one region merely, but in many regions, and have endeavored to pro- duce plants having the widest possible adapta- bility to varying soils and climates. The measure of success that has attended this effort in the case of the grape will be partially revealed in the ensuing pages. [186] • §H?;II s 3 &• 2-* 3.5. a aa898%-S 3*B3R^.|.Sff|eilRfi O C O N *Q 9 ^c«e^ **** LUTHER BURBANK During a period covering 40 years I have prob- ably raised no less than 75,000 to 100,000 seedling grapes from the best table varieties. I have hy- bridized many varieties, both European, Amer- ican, cultivated and wild; also other wild species from Mexico, Australia, China, and Japan. I have likewise attained interesting results by working with bud sports, and with the tuberous grape of Mexico. MATERIALS AND METHOD To raise grape seedlings, it is only necessary to gather the seed from the variety desired, and keep them barely moist until planting time. Plant as soon as the frost is out of the ground in well- drained land, in rows about 3 or 4 feet apart. Scatter the seed thinly in narrow drills. Cover with sandy or leaf-mould soil, about one inch deep in a humid climate, a little deeper in dry soil like that of California. In the latter case it is well to have the upper half of the covering of sawdust, so that the seed- lings do not have too great a weight to lift in push- ing through the soil. During the summer the very poor seedlings, those which are attacked by mildew and which have made weak, uncertain growth may be up- rooted at once, giving the others a better chance. Later, while the plants are dormant, transplant [188] S^SS-S •l!**t ge » f*v •a c^ >-N Ml II LUTHER BURBANK the most promising of these to rows about 12 feet apart, the individual plants being from one to two feet apart in the rows, according to the variety. Like most other cultivated fruits, grapes do not come true from the seed. Among American grapes, if seeds from a vine bearing black fruit are planted, about 99 out of 100 black-fruited seedlings may be expected. With red grapes about the same proportion will follow the parent color. But from a white grape probably less than one-fourth will come white. With the European grape, Vitis vinifera, the most variable and commercially the most impor- tant species in the world, the proportion would be wholly different in most cases. Planting a red grape one may expect half red or half black, the tendency being slightly more toward red or black grapes than white, but the proportions varying indefinitely. Certain qualities of the inherent constitution of the plant are markedly heritable. Thus the seeds from a strong-growing grape vine are likely to produce strong-growing seed- lings. Productive grapes will usually produce a high proportion of productive seedlings. A grape subject to mildew is almost certain to produce a large proportion of seedlings subject to mildew. A variety having abnormally large leaves will [190] A Mammoth Cluster This seedling grape, still unnamed, is a complex hybrid, developed in Mr. Burbank's vineyard. The individual fruits are not large, but they are notable for the extraordinary number in a bunch, as the picture will show. They are also of excellent flavor. LUTHER BURBANK not often reproduce that tendency in its seedlings for an abnormality is more apt not to reproduce itself, there being a tendency to return to the nor- mal condition, which has existed for perhaps a thousand years. By planting seeds of an early grape, a great proportion of early grapes would be expected, and vice versa, but in almost every case both early and late, large and small, black and white, sweet and sour, strong-growing and weak-grow- ing grapes will be produced among a lot of grape seedlings from any variety which has been long cultivated and is the result of hybridization. In a wild species, the variation would be mostly in the size of the plants and very little in any other respect. The first crop of fruit on the young vine is not a very accurate test of its future fruiting capacity. Almost without exception the fruit improves each season for several years both in the size of the bunches and in the quality of the fruit. GRAPES FROM MANY LANDS With the grape as with other plants I have sought material for development in far places; but have also utilized the native species. A brief notice of the different species that have contrib- uted to the experiments will suggest the scope of the work. [192] ft, 5; s 53- LUTHER BURBANK An interesting local species is Vitis Calif ornica. This is an extremely strong vine, climbing a tree to a height of 75 or 100 feet. It is often found along the banks of creeks and rivers where it may attach itself to a young alder. As alder and grape grow, the tree supports the vine until it reaches a height of sometimes 100 feet and has a trunk 12 to 18 inches in diameter — which may seem almost incredible to eastern people unfa- miliar with our flora. The fruit of the California grape is produced in small quantity and is quite variable in this lo- cality. It ripens late, is sour, without flavor, and is generally insignificant in all respects. It is sometimes used for jellies and even for wine. Of the world-wide and supremely important commercial species commonly called the Euro- pean grape (Vmus vinifera) I have worked largely with the Tokay variety with the idea of inducing this vigorous vine, which bears such an abundance of large, handsome fruit, to combine hardy qualities and freedom from mildew with its characteristic excellence of fruit. The fruit of many of the seedlings is quite acid, but some are far sweeter than the Flame Tokay, and much earlier, which is most important as the Flame Tokay ripens too late for our coast climate. These seedlings have of course been rigidly [194] ON THE GRAPE selected to avoid mildew, susceptibility to which is one of the faults of the Tokay, especially in the coast region. Some of the seedlings of the Flame Tokay are white, some black, some red- dish, some of a blue-gray color. Very few of them resemble the Flame Tokay in form, color or qual- ity of fruit, most of them incline to the round form of the ordinary V. vinifera. It is not uncommon to find natural hybrids of the California grape and the European grape growing wild alongside the vineyards. The strains of the California species are in some of the strong- est-growing forms of cultivated grapes that are recommended as stocks for the varieties of Euro- pean grape that are subject to injury from phylloxera. WORK WITH STRANGE SPECIES Mr. M. K. Seralian, who removed from Pales- tine to America some years ago, secured cuttings of the best Syrian grapes. The vines from these cuttings have habits of growth not unlike those of the Flame Tokay seedlings planted at the same time, and are now about the same size. Among them is one identical with our so-called Sweetwater grape. Another was certainly Thompson's Seedless — a stray variety renamed since it was imported to California about 1880, and recently identified as [195] LUTHER BURBANK Sultanina. It is an extremely productive, light colored, strong growing, yellowish-white grape which has to be pruned longer than most others of the vimfera class in order to get big crops which it produces under ordinary vineyard cul- tivation in California. Sultanina and another called Sultana are grapes of medium size but absolutely seedless. They are put up in great quantities in California as seedless raisins, and are displacing the dried grapes of Corinth or so-called Zanta currants so extensively imported from Greece and Turkey— to which they are greatly superior. Among these seedling Syrian grapes there is one early and productive class, absolutely new to California growers. Most of the Syrian grapes are noticeably different in several particulars from the other grapes of Europe and northern Africa. The stems are more slender, the peduncles quite small, yet strong and wiry, the bunches are very pleasing in form, the grapes usually being set full and all of one size, and the bunches are not usually so crowded as those of many varie- ties of the common grape. The seeds also are very small — almost absent. Yet all of the varie- ties among this lot of twelve or more produce some seeds, with the exception of the Thompson's [196] A Nearly Seedless Grape This seedling grape, which reveals the characteristics of ancestors of Asia and Europe, is nearly seedless. It is not large but it has qualities of flavor that are scarcely excelled bij those of any other variety of grape. LUTHER BURBANK Seedless. The seeds, however, are quite tender, being hardly noticeable. The skins of most of them are thin and transparent. Having raised a great number of seedlings from these Syrian grapes, I find them to be re- markably precocious, coming into fruitage early, remarkably heavy croppers, and while more uni- form in character than most of the vinifera seed- lings, yet they nearly all contain an astringent principle which is seldom found in the ordinary grapes. With this exception, they are the most promising lot of seedlings which I have hitherto raised. About 1890 the U. S. Government imported a lot of grapes from the Mediterranean region, but none of them compared with these Syrian grapes, which seem to be distinct, and some of which will probably prove of great value to California. Most of these grapes are oval in form, not round as is usual with other grapes. The Vitis antarctica, which has several other botanical names, is a curious climber from Aus- tralia which I have grown many times from im- ported seed. It is a little tender and especially sensitive to wet weather, and though it is inter- esting I have not experimented much with it. The Vitis Coignetiae from China is an exceed- ingly strong-growing vine with immense leaves. [198] Unproductive but Meritorious Like all of the seedlings now in Mr.Burbank's vineyard, these two are of mixed ancestry. Both have qualities of size and flavor that commend them highly, but they are somewhat lack- ing in bearing qualities. LUTHER BURBANK The foliage is beautifully colored in the fall — scarlet, crimson, yellow, or brown. But there is a great diversity in the seedling vines in the color of the foliage. Those with brilliant scarlet au- tumn colors are generally considered the best. There are also crimson ones. There was a vine growing on my Sebastopol bungalow for years which bore small clusters of insignificant fruit, but handsome foliage. The Vitis hypoglossa is another uncommon grape which I have grown for my own amusement and interest. The Vitis rotundifolia, which has also half a dozen more botanical names, is a tremendous grower. It must be thinned out quite extensively in order to get any fruit; the seedlings of these make a mass of foliage and small branches, so there is no opportunity for the vines to produce much fruit. The various Scuppernongs are derived from this southern species. I have grown them from seed on numerous occasions. In a few cases these have produced scanty fruits, but they were finally destroyed as they make too much growth and too little fruit. I have also grown the mustang or overbearing grape, V. Candicans; the sugar grape, V. rupes- tris; the V. monticola, Texana or Foexeana, the V. [200] Faults of Another Type This seedling grape produces good-sized bunches with an adequate number of individual fruits; but a glance shows that there are far too many small grapes in the bunch. This defect must be remedied by further crossings before the grape is worthy of introduction, notwithstanding the fine quality of the fruit. LUTHER BURBANK vulpina or cordifolia — in fact I have worked more or less with nearly or quite all the North Amer- ican species and many of the hybrids produced by Mr. Munson and others. Seeds of the tuberous grape of Mexico have been sent me several times. It seems to require a thoroughly well-drained soil and a very warm climate. The first two lots of seeds received were fail- ures on account of being placed in irrigated soil which was not suitable to them. Some of the third lot of seeds were placed in sandy, well-drained soil, and made large vigorous vines the first season. They somewhat resemble the Muscat of Alexandria in foliage and growth and have rather large, sweet, potato-like roots. However, our winter climate did not suit them and these also died, so I have made no further attempt at raising them. These Mexican tuberous grapes are said to produce a fine fruit in large clusters, much re- sembling the Muscat of Alexandria. VARIATIONS IN SEEDLINGS OF A BUD-SPORT My constant effort to take advantage of any disturbance in the heredity of a species or variety is justified strikingly in working with the grape. The best seedlings which I have ever produced were from the grape called Pierce or Isabella [202] "My Early Black Grape11 This grape shows the Concord influence, but has strains of various other species. The merits of this new variety are numerous and conspicuous, and its defects are few. It is under- going further observation, however, before being introduced. LUTHER BURBANK Regia, a variety which originated as a sporting branch from the common Isabella on Mr. J. P. Pierce's place near San Jose, Gal. This Pierce grape is the same color as its par- ent, the Isabella, but the berries are more than twice as large though not increased in number on the cluster. The vine is very much stronger and the foliage much larger, so much so that the dif- ference is noticeable at a considerable distance. Large quantities of seedlings from the Isa- bella Regia were raised, partly for the purpose of noticing whether bud-sports would reproduce themselves from seed and partly because it prom- ised to be a fine variety to work upon for im- provement. Among the numerous seedlings which were fruited the variations were most astonishing, much more so than with most grapes. Whether this is on account of the Isabella hav- ing been moved to a new climate, thus changing its hereditary tendencies, or whether bud sports in general are apt to produce more variable seed- lings, I am not yet able fully to demonstrate. Some of these selected vines which were fruited are un- usually strong growers, some were as weak in growth as the ordinary cultivated varieties of grapes; some bore enormous bunches of grapes, some had only a few small clusters. [204] ? s> a I! LUTHER BURBANK One of these Isabella Regia seedlings is the earliest grape ever recorded, ripening nearly a month before the Early Amber, Sweetwater, and other American and European grapes. It is, how- ever, small in size and not productive. THE EARLIEST AND LATEST GRAPES ON RECORD Another very large black grape, produced on a large, vigorous vine, ripens nearly five weeks before its parent. This is the earliest large grape known. It has very delicious flavor and quality. It was temporarily called the "Early Black," but was subsequently rechristened the Montecito by Mr. John M. Rutland, who purchased it for intro- duction in Australia. In contrast with these early-ripening seedlings are others that do not fully ripen their fruit until December and January. These are valuable in California if protected from the rains, as they extend the season almost indefinitely. Though the parent plant bore black grapes, some of the seedlings bore white, yellow, red, or purplish-black fruit. Some varieties were enor- mous producers. Owing to pressure of other matters, I have made no attempt to introduce any of these grapes, but am satisfied that none can compete with some of them for table use. Among the seedlings of the second generation [206] Grapes of the Labrusca Type The Vitis Labrusca, indigenous to the eastern United States, is the native species from which the Concord and Catawba types of grapes, including the Niagara, Brighton, and nu- merous other varieties, have been developed. The variety here shown is of mixed heritage, but reveals the preponderant influence of the Labrusca. LUTHER BURBANK raised from my own vines were three anomalous vines, of great interest. One of these was the exact counterpart of the California wild grape. The second was closely similar though not quite identical; and the third might be called a hybrid in general appearance. As there were no wild California vines grow- ing within fourteen miles of the place where these grapes were growing, I can only account for the appearance of these degenerates, as they might be called, on the theory that our wild California grape and the eastern wild grape from which the Isabella originated were descended from a com- mon stock, and these three plants were reversions. Two of these vines grew the first season to the height of nearly eight feet when the other seed- lings had grown to only one or two feet in height. The third one grew twelve feet or more, while most of the others had grown only about as many inches. The foliage was exactly like the Cali- fornia wild grape, as was the wood, fruit, and general appearance throughout. These seedlings have created much specula- tion as to their origin among experts who have seen them. They are best explained, I think, on the theory proposed above. Nearly three-fourths of the Isabella Regia seedlings bore partially seedless fruit. About [208] A Fine Specimen An unusually large seedling grape with a fine flavor. It would almost seem as if in this seedling the weight of grapes which would ordinarily'be found on a'large bunch had been combined into a few fruits individually of exceptional size. Bunches of this size are very convenient for serving on the table. ON THE GRAPE half the grapes on each bunch usually were alto- gether seedless. Some entire clusters were seed- less. Yet other vines of the same fraternity bore fruit in which the seeds were unusually large. By selection among these vines I have devel- oped several races of nearly seedless grapes that are of exceptional quality. The best of these will be introduced, and they will also be of value in hybridizing experiments for the production of seedless grapes of other varieties. Once produced, such varieties must obviously be propagated by cuttings, but this of course presents no difficulties. The matter of hybridization, crossing, and se- lection of fruit having been gone into quite exten- sively in early chapters, only a glimpse of the special features of the work with the grape has been here recorded. The methods of crossing and selection having been discussed in previous chapters, it would be mere repetition to give them here; and for this reason the details have not been elaborated as fully as in some chapters on other fruits. A great number of experiments with the grape are now being carried on that are approaching completion, and I have a large number of unique and valuable grape varieties which are awaiting introduction. *> 5 § I E:~ THE CACTUS PEAR— A PROFITABLE FRUIT ITS FLAVORS FIXED, Now WORKING MOSTLY FOR SEEDLESSNESS THE story of the spineless cactus has been briefly outlined in an earlier volume, and will be told in detail in a later one. There is no more important story to be told in connection with the record of my entire work, but it would not comport with the purpose of the pres- ent chapter to go into details as to the manner of development of this extraordinary plant. For the moment, we are concerned solely with the fruit of the cactus. In the present chapter it will be considered altogether from that standpoint. It should be explained at the outset, however, that whereas the improved forms of cactus pear about which we are speaking are grown on the spineless cactus plants, yet the fruit itself is not yet altogether without spicules. To remove the spines from the cactus slabs— as the "leaves" are commonly termed — was a task [VOLUME VI— CHAPTER VII] LUTHER BURBANK requiring somewhat less time than the removal of the smaller spines, and in particular of the very minute spicules, from the fruit. The reason for this is not that the spines of the fruit are more fixed and intrinsically more difficult of removal than those on the body of the plant itself, but merely that the work must pro- gress more slowly because it is necessary to wait for a term of years, sometimes four or five, before the cactus plant comes to the fruiting age when grown from seed. Unfortunately it cannot be predicted from observation of the plant itself whether or not it will bear spiny fruit, so it is nec- essary to wait until the plant comes to fruiting age before its characteristics in this regard can be known. On the other hand, the character of the plant itself with regard to spine-bearing is revealed im- mediately when the first tiny shoots come up from the seed. So selection may be made at once among the company of seedlings, and by weeding out those that show any propensity to bear spines, and selecting those that are smooth, the experi- ment may go forward with relative rapidity. We know that we are making no mistake in our selection as regards the bearing of spines on the flattened stalks of the plant, because their character as to this is fixed from the outset, and [214] A Mammoth Specimen Some fruits of this size grow to the number of from twenty to fifty on a slab, and it is easy to ses that the aggregate pro- duction is enormous. In point of fact, the amount of fruit grown on a single acre of Mr. Burbank's new perfected spineless cactus, under favorable conditions, may amount in the aggregate to more than 100 tons in a season. In point of bulk, the crop of the cactus is without rival. LUTHER BURBANK is as definitely revealed when the plant is an inch high as it will be when it has attained mature growth. But, on the contrary, our selection made in the hope of securing plants that would bear spineless fruit of excellent quality may prove eventually to have been hopelessly faulty. After waiting three or four or five years we may discover that the plants on which our hopes had been chiefly based bear fruit as spiny as that borne by their ances- tor whose habits we are attempting to enable the plant to shake off. Nevertheless, the work of removing the spines from the fruit of the cactus has progressed to a stage where the spicules are not only reduced in size, but are so loosely attached that they may be readily brushed from the fruit with a wisp of grass. And the plants under observation include many in which the tendency to drop the spicules from the fruit has advanced progressively, war- ranting the confident expectation that in the next generation there will be some that will present fruit altogether smooth. I have every expectation that when the plants of the most recent generation come to bearing this year, there will be some that produce fruit as smooth-skinned as the slabs of the mother plant itself. [216] A Luscious and Succulent Fruit Mr. Burbank has developed so many varieties of cactus fruit, that there is something like the same range of variation that is found among cultivated apples or pears. All the best fruits, however, are exceedingly juicy and succulent, and most of them are of very appetizing flavor. LUTHER BURBANK Should this prediction come true, my ideal of a spineless cactus bearing smooth-skinned fruit will at last be realized. THE CHARACTER OF THE CACTUS PEAR Meantime the endeavor to improve the size and quality of the cactus fruit has met with signal success. Generation after generation, the "pears" grown on the improved cactus plant have kept pace with the improvement of the plants themselves, until the different new varieties of cactus now bear fruits almost as varied in quality as the different varieties of apples, and perhaps rather more varied than the different varieties of cultivated pears. The fruit of the wild species of cactus varies widely in size and form, as well as in texture and flavor. My cultivated varieties, however, have been made to assume an almost uniform oval form. Or perhaps barrel-shaped would better describe the new cactus fruit. The individual fruits are three or four inches in length, and in some cases they weigh half a pound, although the average weight is considerably less than this. The skin of the fruit is readily removed by cutting off a thin slice at each end and making an incision the length of the fruit, and peeling the skin back. [218] LUTHER BURBANK The pulp thus exposed is as juicy almost as the pulp of a watermelon, but much more com- pact, as well as sweeter and of better flavor. Pulp and skin are usually of about the same color; but the range of color is wide with the dif- ferent varieties, varying from white through the shades of yellow, green, orange, pink, purple, crimson, and the most vivid blood-red to deep purple — almost black. In flavor there is also wide variation. The flavor is characteristic but difficult of description, as it does not bear close resemblance to the flavor of any familiar fruit. There is a wide range of variation as to degree of sweetness and exact fla- vor, just as there is between different varieties of apples or pears. The cactus pear further resembles the orchard fruits in that it may be eaten raw, or may be cooked or variously preserved. It is, in a word, an all-round table fruit, and as such constitutes a very important addition to the dietary. It is best eaten raw. ASTOUNDING PRODUCTIVITY Not only are the individual fruits large and luscious, but they are produced in the most amaz- ing profusion. Some of the seedlings begin to bear fruit the second year, but they do not come into full bear- [220] u 5 d • trolls §= ^ o *i» "•> ^r <* •— LUTHER BURBANK ing — so that the fruit may be accurately appraised — until the third or fourth year. Then the fruit may be produced so abundantly as to check the growth of the plant. When the cactus has come to mature age, it puts forth such an abundance of fruit as sometimes almost to hide the slabs from which the fruit grows. Half a hundred in- dividual fruits may grow on the edges or surface of a single slab. Looking across a field of cactus in full fruit, one sees a mass of fruit that almost hides the plant. It has been found that eighteen thousand pounds of fruit per acre is a common crop on the poorest soil. The possibilities of production on good soil and with fully matured plants of the perfected varieties are probably greater than those of any other fruit-producing plant whatever. It has been estimated that the product of a single acre may amount to the astounding quan- tity of one hundred tons. Whoever has seen a field of my giant cactus plants in full fruit will not be disposed to chal- lenge the estimate. Analysis shows that the fruit contains about fourteen per cent, sugar together with a small amount of protein and fat. The precise appor- tionment of the constituents varies greatly with [222] «l P* »^- &?ft "Pr-^ae'-^ 3 c* ^£ »£ 3 * 0> ,-. c. »'*ISB. =1^:1='^ K^TrS- LUTHER BURBANK different varieties. It is possible to increase the sugar content and otherwise to vary the chemical composition of the fruit by breeding and selec- tion, just as can be done with the apple, the peach, the plum, the sugar beet, and most other fruits and vegetables. The cactus fruits developed at Santa Rosa are of exceptional size and superior quality, but of course they do not constitute an absolutely new departure, for it is well-known that there are many varieties of spiny cactus that bear edible fruit. Indeed, in certain arid regions, and in partic- ular about the Mediterranean, the fruit of the cac- tus has long been recognized as a valuable food product. Professor Leotsakos of the Greek Uni- versity at Athens, who visited my grounds one summer recently, tells me that the cactus fruit is a very important part of the dietary of millions of people around the Mediterranean for about three months of the year. He declared that he himself would prefer a half dozen good cactus fruits for breakfast to the best beefsteak. He considers the fruit both nutritious and healthful, and this estimate is universal in coun- tries where it is largely eaten. It is the custom in Greece, especially along the seashore, to collect the cactus fruits in the morn- [224] i a- « » s> j=. P6 3" >1 « « 2 LUTHER BURBANK ing and store them in some cool place, either with ice or in a basket of sea water, which is said to improve the flavor of the fruit. Both wealthy and poorer classes eat the fruit at each meal through- out the season, according to my informer. So im- portant is the cactus fruit regarded in Greece that Professor Leotsakos assured me that he would make haste on his return to communicate with the Government officials, that they might at once take steps to obtain my improved varieties for planting; for, of course, no variety of cactus hith- erto known approaches the new hybrid species in quality or productivity. It appears that the cactus fruit is usually known about the Mediterranean as the Indian Fig. In this country it has been commonly referred to as the Prickly Pear. But now that the prickles are marked for elimination, this name will cease to be appropriate, and we may conveniently refer to the fruit as a Cactus Pear, unless some more distinctive name should be suggested. VARIOUS USES OF THE FRUIT The juice of the crimson variety of the cactus fruit is a brilliant carmine color that makes it very valuable for coloring ices, cakes, and con- fectionery. It is not only absolutely harmless but positively nutritious and beneficial, and is sure to gain popularity; taking the place of the arti- [226] A Sturdy Variety All of Mr. Burbank's perfected spineless Opuntias are very complex hybrids. As usual with hybrids, these plants show a marked tendency to wide variation. Even where the slabs are comparatively uniform, there is great diversity in form and col- or of fruit, giving the plant developer a free hand in selection. !ttl*'"':l.*£i1 *!IVB!I!I!; a!Mlll!~: 2<*-cS'ecl!l? sj-tarS'c i;^^^~. ^^sa.ir^cS C^ C LUTHER BURBANK bearer. Already the fruit has been made large and of better flavor, and the seeds have been mini- mized. With the aid of crosses of the species named, and also, probably, with the introduction of the racial strains of a wild species of western Texas, Utah, and Mexico (Herberts fremonti), which I now have under culture, and which some- times bears fruit of exceptional size and superior quality, though not as abundantly as most other species, it should be possible to produce a new race of barberries that will be a valuable addition to the rather meager list of small fruits. IMPROVING THE ELAEAGNUS During the early years of my work in Cali- fornia I kept in close touch with all the importa- tions made from Japan by the H. H. Berger Co., of San Francisco, and others. From them I re- ceived, among other plants, a curious fruit-bearing plant from Japan, known in its native country as the Goumi Berry, and classified by botanists as Elaeagnus longipes. No other importation of a member of this genus had hitherto been made, so I viewed the plant with particular interest, and was especially struck with the seeming possibilities of improving its fruit. The Elaeagnus longipes bears flowers of a bright, brownish-yellow color, subject to a good deal of variation. The fruit is a berry of varying [246] ON INEDIBLE FRUITS shades of crimson, rarely changing to yellow. The flavor of the fruit is far from inviting. After one has tasted five or six of the berries, one is scarcely able to describe the flavor or to decide whether others have any desirable quality. The astringency of the fruit is so great as nearly to obliterate one's sense of taste after two or three have been tested. Perhaps it should be noted that the tasting of fruit for the purpose of testing its quality becomes a rather unwelcome task for the fruit developer even when the fruits under consideration are plums or peaches or other orchard fruits of the finest quality. Visitors have often assured me that they would consider it a very great privilege to test different fruits by the hour. But such an offer only showed their inexperi- ence. No one cares for fruit after he has eaten a certain quantity, and the necessity of tasting one kind after another becomes for the fruit developer who operates on a large scale a highly distasteful task. If this is true when fruits of fine quality are in question, it must obviously be doubly true of undeveloped fruits like the Goumi Berry, the eat- ing of which gives nothing but discomfort from the outset. But it is equally obvious that no progress can [247] LUTHER BURBANK be made unless the fruits are constantly tested in order to select the best for the continuance of the experiment. And as there is no known substitute for the human palate in making such selection, the tasting of fruits must be regarded as an un- avoidable part of the plant developer's every day work. In the case of the Goumi Berry, my efforts at selective breeding have been rewarded by the notable progress of the plant, first in the elimina- tion of the thorns, and secondly, in the improve- ment of the fruit. Here and there I have found a seedling, the fruit of which is pleasant to the taste, and by selec- tion through successive generations a variety of Elaeagnus has been produced that gives great promise of eventually growing a fruit of real value. My experience with the genus has included tests of five species, all imported from the Orient, bearing the specific names of Elaeagnus augusti- folia, E. umbellata, E. pungens, and E. argentea, in addition to the original E. longipes. There are three closely related plants also belonging to the Oleaster natives of North America, these being, E. canadensis (sometimes called Shepherdia cana- densis), E. argentea, the buffalo berry (sometimes called Shepherdia argentea), and E. argentea, the [248] B s-'l S"* 8.5 P Is ?a|i®^? lli^S -^ C"«, r»e«9a^S'i;"* ~-~O eHi!£t»9i!ie LUTHER BURBANK silver berry of the far west; all somewhat similar plants in general appearance, but quite different from the Elaeagnus of the eastern hemisphere. The seeds should be treated like those of the pear — removed from the fruit when fresh, thoroughly washed, and kept fairly moist until planting time. The seedlings grow rather slowly at first, but offer no particular difficulties. I have made various attempts to cross the dif- ferent species, but thus far without success, chiefly because the plants bloom at widely different seasons. Up to the present, therefore, the improvement has all been due to selection and to crossing within the species. After many years of selection my stock has finally been reduced to a single plant, a large bush bearing most abundantly each season. The fruits are large and of very good quality. In- deed, the improvement has been so marked that it is not unlikely that this variety, when it has been more fully tested, will be introduced. It has certain attractive qualities that seem to make it worthy of a place in the fruit garden. The best varieties of the American Elaeagnus, especially the buffalo berry and the silver berry, are well worthy of cultivation, and extremely promising for work, being enormous bearers of pleasant-flavored, currant-like fruit, which in the [250] ON INEDIBLE FRUITS wild state is often collected for making jellies, and is far better in quality than the goumi berry of Japan, although very much smaller. The best of all these species bear fruit in astounding quantities. The crossing of the best varieties of the American and the Asiatic Elaeag- nus gives as good promise of important results as any fruits that I can mention. A UNIQUE CHINESE FRUIT WITH GREEN FLESH Another importation from the Orient that seems pretty certain to be welcomed here, is a plant indigenous to China, belonging to the genus Actinidia, known to the natives as the mao-li-dzi. The English interpretation of this word is said to be something like "Hairy Plum." As described by a missionary from whom I received the seeds of the plant, the Hairy Plum grows as a vine, and has a fruit with bright green flesh, containing seeds not unlike those of the strawberry, and with a thin brown skin covered with a downy coat like that of the peach. The fruit is said to resemble the strawberry in taste. It is described as delicious when raw, and also as very good when cooked. My informant further states that the seeds are obtained from a plant growing in the mountains at an altitude of about five thousand feet. He de- clares that the fruit is popular, and that efforts [251] LUTHER BURBANK have been made to induce the Chinese to make a business of growing it, but that hitherto it has been necessary to depend entirely upon plants growing wild in the mountains. The vine clambers over the underbrush on the mountainside like a grapevine. It is, of course, very hardy. One of the attractive features of plants of this tribe is the ease with which they may be propa- gated. Not only can they be grown readily from seed, usually producing new varieties, but they grow also from soft or hard wood cuttings, from tip cuttings, or by layering. When a new variety is produced of the desired type, it can be multiplied indefinitely by dividing any part of the plant into sections and placing these under conditions suitable for growth. Some of the plants of the genus are true climb- ers. Most of them, however, trail upon the ground, usually hugging it closely. Those that climb are valuable for covering screens, arbors, walls, and low buildings. The trailers are valuable for dec- orative purposes and quite often for their fruits. In Corea and Manchuria the long, slender vines of Actinidia polygima (the species with which my experiment began) are used for cordage. Other species are used in the manufacture of paper. [252] A Bush of the Juneberry The Juneberry is one of a number of interesting shrubs belonging to the rose family. The common form, known to the botanist as Amelanthier botryabium is a native of the eastern United States. It bears a juicy fruit of fairly good flavor, which jnerits the attention of the plant developer. There is every prospect that it will prove susceptible of great improvement. LUTHER BURBANK My first introduction to the genus was through a number of large plants of Actinidia polygima received in 1904 from an American miner in Gorea. The seeds already referred to were received five years later. The first fruit buds appeared on the plants in 1912. But different species vary as to the age at which fruiting begins. Some species fruit in the first year from the seed. The ones under my observation have fruited too recently to enable me to do more than observe their attractive qualities, and form a general opinion as to the possibility of improving them. I have, however, after testing fruit from a number of species, selected an extremely hardy, rugged variety from the high mountains of Western China that bears a really delicious fruit. The vine may be grown as readily as the grape, and its improved varieties promise to be a very valuable addition to the list of American fruits. Its full possibilities of development, however, can be judged only after more extended observations. IMPROVING THE MYRTLES More familiar exotics, some representatives of which have so long been under observation in America that they seem almost like natives, are the various members of the myrtle family. These are curiously divergent. Some of them are small trailing vines, yet the family includes also the [254] ON INEDIBLE FRUITS gigantic Eucalyptus trees that grow to such im- mense size in Australia and California. True myrtles are mostly natives of the Southern hemisphere. There are representatives of the tribe, however, that thrive in the tropical and sub-trop- ical regions of our own hemisphere, among these being the plants that grow the fruit known as the Guava. The species of myrtle that chiefly concerns us in the present connection is a tender shrub with slender branches, known as the common myrtle, and classified by botanists as Myrtus communis. There are numerous varieties of the shrub, some of them bearing white or yellow or varie- gated leaves. The tendency to produce these variegated leaves may exist as a latent character- istic in the green-leaved variety. I have grown a beautiful variegated variety from the seed of the ordinary green myrtle. As a rule the progeny of the "sport" thus produced tends to revert to the original type. And in point of fact it is observed that all plants with variegated foliage have a very strong tendency to produce green-leaved seedlings. The fruit of the common myrtle is small, black, and hardly edible. I have imported many species and varieties from Chili and Patagonia, however, which, although appearing very much like the common myrtle, bear fruit quite different in ap- [255] LUTHER BURBANK pearance, being pink, white or yellow. The indi- vidual berries are usually as large as huckleber- ries, sometimes considerably larger, and have delightful aromas and flavors. Some of these new fruiting myrtles will grow on very dry ground; others require soil that is constantly moist. At three or four years some of the trees of the Chilian and Patagonian species are used for tim- ber, and grow to a height of twelve or fifteen feet, with a breadth of ten feet. The branches often droop gracefully like those of the weeping willow, and are heavily loaded with oval, small, glossy green leaves. These are not the fruiting species, which grow to a height of two to four feet, and sometimes of equal breadth. Another species that bears fruit when quite young, sometimes even in the second year, has been received from South America, and is identi- fied as Myrtus ugni. This plant bears a curious resemblance to the gooseberry, except that it has no thorns. Its berry is a glossy purple, sometimes slightly hairy, growing in compact drooping racemes like the currant. Some of the berries are of excellent flavor, others woody or filled with seeds. Several thousand of the best seedlings from these exotic myrtles are now growing on my place, [256] sss-ssssse t> c* cs I**!? *r*fia ? gftJ^Ssi^S^o?^^ 3 s ? 1}^ LUTHER BURBANK and there are indications that some among them will almost certainly prove of value as fruiting plants for general culture. All of them appear to be hardy enough to stand the climate of the central United States. It is to be expected that hybridizing experiments will further improve the fruit. The material is now in hand for such experiments. SOME NEGLECTED RELATIVES OF THE RASPBERRY Not to leave the field entirely to exotics, we must note that there are several members of the great Rubus family, closely related to our culti- vated raspberries and blackberries, that grow at our very door, so to speak, yet which have been hitherto neglected or given slight aid in the devel- opment of the latent fruiting possibilities we may confidently expect in most members of this family. Among these are plants of a group represented in the eastern United States by the Flowering Raspberry, Rubus odoratus; in the central region by Rubus deliciosis of Colorado, and along the Pacific Coast from Alaska to Southern California by the Thimble Berry, Rubus nutkanus. The eastern species is a handsome plant with deep, pink flowers that make it suitable for orna- ment. The Thimble Berry grows among the weeds of the lower hills and valleys, sometimes climbing high up the mountain slope, and in Southern [258] The Stem of the Russian Barberry The barberry is well known to be a very thorny plant, but the Russian species is peculiarly well armed, as this pic- ture testifies. Now that thornless blackberries are in evidence, the plant-developer will be expected to remove the thorns from the barberry at the same time that he improves its fruit. LUTHER BURBANK California seldom venturing below an altitude of five thousand feet. No other shrub on the Pacific Coast exhibits a more pleasing effect than a broad expanse of the soft, delicate, green foliage of the Thimble Berry. Its large, white flowers, flat, button-shaped red berries, and sweet, resinous, woody fragrance add to its attractiveness. The flowers of the Thimble Berry are not so large as those of its eastern relative, but their delicate, pure white petals scattered among the large, pale green leaves, add to the beauty of the banks of foliage that overshadow the other forest flowers. The thin, button-shaped berries are often of a brilliant red, though sometimes paler, but are extremely soft so that they can be picked with difficulty. The fruit, though edible, is of little value, being somewhat acid, and lacking flavor. Yet the aristocratic lineage of the plant makes it seem probable that its fruit may be susceptible of development. I have attempted to cross the Thimble Berry with nearly all cultivated varieties of raspberry and blackberry, but have never succeeded in effecting hybridization, unless this has been effected in some hybrid seedlings of last season, which from the foliage would appear to have resulted from a cross. [260] A Russian Barberry Bush Mr. Hurbank has followed his usual custom in going to differ- ent countries for material, in his hybridizing experiments in the attempt to imiirove the fruit of the barberry. A plant of the Russian species which Is being utili:cd along with others Is here shown. LUTHER BURBANK The Rubus deliciosus, the Colorado species, is similar to the eastern one in most respects, except that the blossoms are white. All three species are almost thornless; the Colorado species practically wholly thornless, though the fruit of none of them is of any value. The hardiness of the Thimble Berry and its trailing habit suggest interesting and unexpected possibilities for its fruit, if a cross could be effected that would introduce the lacking elements of size and texture and flavor. Other Rubuses that seem worthy of attention are the Bridal-rose, Rubus rosaeflorus, and the Wine-berry, Rubus thoenicolasius, both natives of Japan and China. The former is a double-flowering plant, often cultivated for its flowers. It thrives well in Cali- fornia in cool, shady places. The double-flowering varieties, in my experience, do not fruit, but there is a closely related form that produces single flowers that mature fruit of an inferior quality. The Wine-berry was introduced into America about twenty years ago by Mr. John Lewis Childs. As an ornamental plant it is quite promising. But its fruit, in its present state, is of no value. The bright, cherry-red or sometimes salmon- colored berries are usually small and soft, slightly acid and insipid. But the strong, graceful, recurving branches, [262] niHIHil] I«fi|i||i5!jlj o. -» a. a 3s 5 § C0c. ^NO-3 ^ § S=-a?asr5i^.a aft3.^|S^3 ^3-0 3 ? §^ a « V Ka * 2 ^-~s3 § 5af3?s? § a.o- LUTHER BURBANK and the large ample leaves, with their white under surfaces, make the Wine-berry a beautiful and attractive shrub. And although the experiments that have been made with it on my farms have not suggested great promise as to fruit production, yet I wish to state that the experiments were not conducted extensively, nor for a long period, and do not regard them as conclusive. Pending further investigation, the wine-berry must be regarded as possibly presenting oppor- tunities for the development of a new fruit-bearing Rubus. Conceivably the attempt to hybridize this species and the Bridal-rose or the ordinary rasp- berries might lead to interesting results. FRUIT-BEARING SHRUBS Among other plants with undeveloped fruiting possibilities are some shrubs of the heath family (Ericaceae) , relatives of the rhododendrons among flowering shrubs and the huckleberry among fruit bearers. Of these the best known is the form of Arbutus called the Strawberry tree. This is commonly grown both in Europe and America, and consid- erably prized as an ornamental shrub. It is a small shrub, varying a good deal in size, but com- monly growing to the height of about six feet. It bears berries that vary in size and color, but [264] ON INEDIBLE FRUITS which in general are red, suggesting the common name given the shrub. There are several other species of Arbutus, among them some of the most beautiful trees and shrubs for the adornment of lawns. One of the most prized species is the California form known as the Madrona, which sometimes grows to a height of about one hundred feet, and which bears ovate leathery leaves not unlike those of the Magnolia. This tree is quite hardy, even in the mountains of California, its native home, and its leaves, blos- soms and fruit are ornamental and attractive. The blossoms grow in clusters, sometimes erect and sometimes drooping. They are white in color, and very fragrant. The berries, orange or scarlet in color, somewhat resemble those of the Unedo or Strawberry tree, but the clusters are more numer- ous and smaller. A singular thing with regard to both of these forms of Arbutus is that blossoms and ripe fruit may be seen on the tree at the same time. In this respect the Arbutus resembles the orange tree. I have often thought that a handsome tree could be produced by crossing the Unedo or Strawberry tree with the Madrona, and I have no reason to doubt that the cross could be made. I regard the Arbutus as a promising tree for experimentation. [26:] LUTHER BURBANK My own experiments with the shrub have been confined to the raising of seedlings for ornamental purposes. I observed that the Strawberry tree, like the Madrona, varies in size and sometimes in shape and color of leaves and fruit. I am confi- dent, therefore, that by special cultivation and selection the Strawberry tree might be improved and made to bear a very fragrant and luscious fruit. "Various members of the genus are available, and there is good prospect that experiments in selective breeding, with or without hybridization, would reward the experimenter. Two other shrubs that give good promise are the Hawthorn and the Mountain Ash. The Haw- thorn in particular is an extremely valuable shrub, and gives very great promise of the produc- tion of improved varieties of fruit through selective breeding. The Mountain Ash is usually raised for the beauty of its fruit. I have made experiments in selective breeding with this plant, and have greatly improved the size and beauty of the clusters of fruit. With the Hawthorn also I have made some interesting experiments, but there is fine oppor- tunity for other workers in this field. Indeed, the work of developing this fruit has made only the barest beginnings [2661 The Fruit of the Barberry These clusters of barberry fruit represent varieties im- proved by Mr. Burbank through selection. The plants on which they grew will be utilized for further development in crossbreeding and additional selection. It will be seen that the fruit already has a very promising appearance. LUTHER BURBAXK I would especially emphasize the fact that there are peculiarly inviting opportunities open to the amateur in connection with this familiar but almost totally neglected plant The hawthorns are hardy shrubs or small trees. of vigorous growth. There are about seventy species available for hybridizing experiments, and some of them already bear fruit that seems fairly to beckon the would-be developer. Doubtless the original apple — the progenitor of all modern varieties — was no better than the best of the present native hawthorns. Who will give us a new race of fruits to compete with the apple. through bringing out the only half-hidden quali- ties of this responsive shrub? — Largely by chance, certain plant* have come under the tutorage of man, and thus have been brought about the fa- miliar fruit* of our orchard*, vineyard* and berry patches; who can predict the surprise* which the orchard* and vine- yard* and berry patche* of the next generation will rev e a I ? THE NEED FOR IMPROVING SMALL FRUITS AND SOME OF THE MEANS FOR MEETING IT WITH the present chapter we conclude our survey of the fruits proper, and it will be well to make a brief review of the subject, in particular with reference to the out- look, and the possibilities of further progress in the near future. In making this general review, we need not confine attention absolutely to the small fruits. Much that is said will refer to fruits in generaL But doubtless there are larger opportunities for improvement with the berries and garden fruits than with the familiar orchard fruits, chiefly be- cause the latter have been given a far larger share of attention by the horticulturist and fruit devel- oper in the past. The large size and varied uses of apples, pears, peaches and plums, in particular, have made them popular everywhere, and have caused a vast deal [VOLUME VI — CHAPTER IX] LUTHER BURBANK of attention to be given them. So almost number- less varieties have been developed which meet the most varied requirements. But the small fruits have been the Cinderellas of the pomological fam- ily. Our own generation was first to give them proper recognition, and it remains for our suc- cessors to carry them forward to their true plane of utility. So it is these fruits rather than others that we shall have chiefly in mind, as the title of the pres- ent chapter would suggest. But I repeat that much that will be said applies to all marketable fruits, and even where a particular species is referred to, what is said is often susceptible of general appli- cation. Bearing this in mind, let us briefly review the story of the modern development of the small fruits, and with equal brevity outline a few sug- gestions as to the lines of future progress. THE INCREASED CONSUMPTION OF FRUIT The consumption of fruit has increased more rapidly in the United States, and perhaps through- out the world, during the last one hundred years than has that of any other kind of food, with possibly the exception of nuts. The increase in the consumption of both fruits and nuts during the past twenty years has been particularly re- markable, and they are in fact coming to be [270] ON THE NEED FOR IMPROVEMENT regarded as food staples, as they certainly should be. As an illustration, take the case of the straw- berry. This was about the first small fruit com- mercially grown in the United States to any great extent. Early in the 19th century a few were raised in New Jersey for the market in New York City. Those who first engaged in this enterprise soon found that to keep up with the increasing demand, it was necessary to go into the business on a much larger scale, and raising strawberries by the acre for the market became an industry. At the time it was prophesied that there would be an over-production of strawberries, and that they could not be sold. But now whole train-loads of strawberries and other berries are brought into New York City daily during the season. Probably a carload of strawberries is consumed today in the United States to every cultivated strawberry that was eaten one hundred years ago. The consumption of the tree-fruits, grapes, and other small fruits has increased in a somewhat similar proportion. America has had an important share in recent fruit advancement. When the immigrants came from other countries to America they usually brought with them some of the seeds or cuttings of their favorite fruits; these were planted and [271] LUTHER BURBANK orchards were grown. And in the course of events, when the families began moving westward, they usually selected seeds from their best fruits for transplanting. In this way a constant and natural selection has been going on from the very first; the poorer varieties being discarded and forgotten, while those that filled a want and had proved productive and valuable were cherished. After this sifting process of the years, only a few of the older fruits, in proportion to the num- ber now cultivated, are still considered standard varieties. Especially during the last twenty-five years, new varieties of strawberries, raspberries, black- berries, currants, gooseberries, cherries, plums, prunes, apples, pears, peaches, nectarines, quinces, figs, and oranges have been produced and are now favorite fruits. The old varieties of these fruits, however, are slowly but surely being supplanted by still later productions. NEW VARIETIES TO MEET NEW CONDITIONS This process of evolution is wholly imper- ceptible to the careless observer; but to one who watches closely the development of fruits, there is an unmistakable and rapid change now going on. Old orchards are continually being grafted [272] Fruit of the Chilian Myrtle This is another of the almost numberless tropical species with which Mr. Barbank has experimented in the endeavor to develop new types of orchard and garden fruits. The berry of the Chilian myrtle has a pleasant odor and taste, and there is suf- ficientvariation to suggest the possibility of improvement through selective breeding. It may prove possible, also, to cross the plant with one of the other myrtles, stimulating variation, and giving further opportunity for selection. LUTHER BURBANK over to new and improved varieties, while the new orchards added from year to year are planted to the latest standard fruits. This is especially true on the Pacific Coast, as competition is keen and the tests given fruits must be exacting. Luscious, sun-sweetened fruits must be pro- duced which will bear shipping long distances, to less favored climes, retaining their form, color and flavor. Transcontinental shipping is one of the severest tests that can be applied to any fruit — and it is distinctly a new test. Most of the older fruits had been selected for family use and home marketing; very few of them consequently could meet this new requirement. Notwithstanding the fact that practically all the best fruits in the world have been tested in Cali- fornia, only a few of the Eastern or European varieties have been able to meet the conditions here, and to fulfill all the requirements demanded. At present probably one-half of the fruits grown in California, with the exception of the French prune, are varieties that have originated, or at least have risen to commercial importance, within the state; and this statement applies with almost equal force to the states of Oregon and Wash- ington. There is a great field of usefulness open to the [274] ON THE NEED FOR IMPROVEMENT enterprising plant breeder in the adaptation of fruits to different localities and climatic condi- tions, thereby extending the belt in which certain fruits can be raised. Some regions are too arid; some too cold, oth- ers too warm, or too damp and with too frequent rains for certain fruits. It is the mission of the plant-breeder to develop varieties that will with- stand these conditions. What greater good can be accomplished than making exquisite fruits that will grow abundantly in sections of the country where none could be grown before? CLIMATE, DISEASE, AND HUMAN TASTES In creating new varieties to meet local condi- tions, it is usually necessary to bear in mind not alone edible quality of fruit, but the constitution of the plant itself. Hardiness is often a sine qua non, particularly with fruits intended for the new regions of the Northwest, where the winters are extremely cold. Then nearly all kinds of fruits are subject to fungous diseases of some sort. These must be combated by developing hardy, resistant varie- ties. Some advancement has already been made in this direction; but much remains to be done. The careful plant-breeder will watch intently his stock and promptly discard all susceptible plants. [275] LUTHER BURBANK It is in this way alone that such diseases can be thoroughly and permanently conquered. In some parts of the United States the sun's heat is too fierce and the air too dry for fruits to thrive which have been accustomed to more favor- able conditions. For such regions varieties must be developed which are low, compact growers, producing an abundance of thick, leathery leaves, and fruit that will not easily sunburn. Some of the Eastern varieties, having become adapted to a moist cli- mate, are open growers, bearing rather thin, deli- cate leaves. Such varieties are usually total fail- ures when introduced in the arid Southwest. In developing a new fruit, the plant-breeder must not only meet the exacting demands of Na- ture, but also the exacting and increasingly com- plicated demands of the grower, the shipper, and the consumer; for together they constitute the jury that finally determines the value of his prod- uct. The tests of these jurists are applied from different standpoints and for different purposes. The grower is solicitous for an early-bearing, prolific tree, immune to fungous diseases or insect pests; one that will flourish with little care, prun- ing, or other attention. The shipper and dealer are unconcerned about the characteristics of the trees, or their produc- [276] 1 1* ffie^* § ft c 5 ._ ^^ Wifil • oe»s?«.l 3§ so^-i c'o ^r"^5^ ^S^i-^iltt^c^^^S. fc_ a g.2 5 IB •• ft * ^«a * I I 83i£ 2-