7 WU i —— ———————— —— iu (Wn 3 wera > tan ~\ alr vii N a Presented to the UNIVERSITY OF TORONTO LIBRARY by the ONTARIO LEGISLATIVE LIBRARY 7 i4 “a HOW PLANTS ARE TRAINED TO WORK FOR MAN BY LUTHER BURBANK S&c.D : x GARDENING VOLUME V EIGHT VOLUMES * ILLUSTRATED PREFATORY NOTE BY DAVID STARR JORDAN P. F. COLLIER & SON COMPANY NEW YORK Copyright, 1914 By THE LUTHER BURBANK SOCIETY All rights reserved Copyright, 1914 By THE LUTHER BURBANK SOCIETY Entered at Stationers’ Hall, London All rights reserved Copyright, 1915 By THe LUTHER BURBANK SOCIETY Entered at Stationers’ Hall, London ; All rights reserved Copyright, 1921 By P. F. CoLLieR & SON COMPANY MANUFACTURED IN U. S. Ay CONTENTS Tue Cactus PEAR—A PROFITABLE FRUIT FRUITS WITH UNIQUE QUALITIES Tue NEED For IMPROVING SMALL Os 5 MEN Pn ae ay gel How THE GARDEN May BE MapE More PRODUCTIVE SomME CoMMON GARDEN PLANTS AND TuerR IMPROVEMENT | PrEAs AND BEANS AS PROFITABLE CROPS THe Tomato— AND AN _ INTERESTING E.XPERIMENT Some Priants UsED For FooD AND FLAVOR ARTICHOKES AND OTHER GARDEN SPE- CIALTIES WINTER RHUBARB AND OTHER INTEREST- TO OIC ae Aes 1 1i—Vol. 5 Bur. PAGE 129 157 189 217 239 2 CONTENTS THe CAmassta—WiL1L It SUPPLANT THE Potato? THE Porato ITtseELF —Wuo Wi. In- PROVE It FurTHER? Corn — ‘THE Kine or America’s Crops THE FAMILY OF GRASSES PAGE 261 285 311 341 LIST OF ILLUSTRATIONS A Burpank STRAWBERRY. . . Frontispiece PAGE A Cactus Fruir THat ImMIvTATES THE ORI armen SET AN EN Mant «| Cactus FRUIT ON THE SLAB ko A Goop SPECIMEN Si UE IED A WELi-ProporTIONED Fruir . . .— 20 FRuIt oF A CHILEAN MyrT1E . . .— 28 THe FRUIT OF THE STRAWBERRY TREE. 382 Fruit oF ONE oF My GREATLY IMPROVED VARIETIES OF MOUNTAIN ASH . . 386 THE Resutt oF EpucaTion . . . .. 42 A CLUSTER OF THE NEw WHITE ELDER- NER Pon cent Cate Pee re ane > OS AR 50 CoLor VARIATIONS IN THE CANES OF THE Hypreip BLACKBERRIFS . . . . 56 THE STEM FINALLY SELECTED . . =. 62 ERY FEAMPOr is MOR here ha) Th 4 LIST OF ILLUSTRATIONS PAGE PA MATTE OL MEER Oe eo ILLusTRATING LEAF STRUCTURE. . . 88 WHERE THE TREE Is ALIVE. . . . 94 ‘COMPOST FOR Youne Puiant Foop . . 102 SOME EXPERIMENTAL GouRDS . . . 108 SomME GOURDS FROM | AUSTRALIA: 65): See meee, FAMILIAR BEEP) i. ee BNOTHER OLD PRIEND 0. 6 eee PARSNIPS: sen rome ePBS avi hh 17) 6c) +6 CowpEsas UNDER CULTIVATION. . . 184 SHOWING VARIATION IN [BEANS . . . 146 A STRIPLING FROM THE Tropics . . 152 Fruits oF A Tomato Hypripy . .... 160 POTATOES WITH A STRANGE History . 166 TRANSPLANTING SELECTED SEEDLINGS . 172 A Soutn AmERICAN ALLIUM . .. . 194 A New ATAS0OE os Sua or. eo A Basket oF BuRBANK PEPPERS . . 210 BURBANK PEPPERS ())) (iw OA. 6. RS ARTICHOKES SPIN Dab eh Pieces 9h a HaA.rFr-OPENED ARTICHOKE BLossom » 84 LIST OF ILLUSTRATIONS A Wi ARTICHOKE AN IMPROVED ARTICHOKE FLOWER AND FRUIT ON THE SAME PLANT A BED oF SELECTED CROSSBRED CAMASSIAS A WuvdE RANGE OF VARIATION CAMASSIA BLOssoMs THE WILD CAMASSIA Wip Hicu ANnpbeEs PotaTors SomME SELECTED SEEDLINGS A FINE New Earty Potato A FREAK Ear oF CorRN SECTIONS OF RarInBow CorN LEAVES THREE FINE Tyres or Corn WHEAT GERMINATING ON ICE ‘A Guimpse aT My WueEat EXPERIMENTS 5 PAGE 228 234 254 264 270 274 280 288 294 300 314 322 330 344 348 THE CACTUS PEAR—A PROFITABLE FRUIT Its Fiavors Fixep, Now Worxine Mostriy FOR SEEDLESSNESS HE 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 present chapter to go into details as to the man- ner 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 in all cases altogether without spicules. To remove the spines from the cactus slabs— as the “leaves” are commonly termed—was a task 7 8 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 with any degree of certainty be predicted from obser- vation of the plant itself whether or not it will bear spiny fruit, so it is necessary to wait until the plant comes to fruiting age before its charac- teristics 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 seedlings, and by weeding out those that show any propensity to bear spines, and selecting those that are smooth, the experiment 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 THE CACTUS PEAR 9 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 nearly as spiny as that borne by their ancestor 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 in several varieties are as smooth and free from spines and spicules as an orange. And the plants under observation include many in which the tendency to drop the spicules from the fruit has advanced progressively, warranting the confident expectation that in the next generation there will be many more that will present fruit altogether smooth. I expect that when the plants of the most recent generation come to bearing some will produce smooth-skinned fruit. A CACTUS FRUIT THAT IMITATES THE PEAR Fruit of this type is not quite so well adapted for packing as the oval type, but many people like a pear-shaped fruit, and this form has been retained in a number of our best varieties. THE CACTUS PEAR 11 Should this come true, my ideal of a spineless cactus variety bearing smooth-skinned fruit will at last be wholly 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 them- selves, 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 culti- vated pears. The fruit of the wild species of cactus varies somewhat widely in size and form, as well as in texture and flavor. My cultivated varieties, how- ever, have been made to assume an almost uni- form 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 consider- ably less than this. The skin of the fruit is readily removed by cutting off a thin slice at each end and making 12 LUTHER BURBANK an incision the length of the fruit, and peeling the skin back. 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 far better flavors. _ 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 flavor, 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 an all-round table fruit, and 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. THE CACTUS PEAR 13 Some of the seedlings begin to bear fruit the second year, but they do not come into full bearing—so that the fruit may be accurately appraised—until the third or fourth year. Then the fruit may be produced so abun- dantly 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 some- | times almost to hide the slabs from which the fruit grows. Half a hundred individual 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 plants. 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. The product of a single acre may amount to the astounding quantity of twenty-five to thirty tons. Whoever has seen a field of my giant cactus plants in full fruit will not be disposed to chal- lenge the facts. CACTUS FRUIT ON THE SLAB This picture suggests the enormous productivity of our new spineless varieties. The slabs here shown are in no wise exceptional; indeed, they bear no more than an average number of fruits. Sometimes a single slab bears more than fifty of these “pears.” Se THE CACTUS PEAR 15 Analysis shows that the fruit contains about 14 per cent sugar together with a small amount of protein and fat. The precise apportion- ment of the constituents varies greatly with 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 though very spiny fruit. Indeed, in certain arid regions, and in partic- ular about the Mediterranean, the fruit of the cactus has long been recognized as a valuable food product. Professor Leotsakos of the Greek University 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. 16 LUTHER BURBANK 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- ing and store them in some cool place, either with ice or in a basket of seaweed, which is said to improve the flavor of the fruit. Both wealthy and poorer classes eat the fruit at each meal throughout the season, according to my informer. So important is the cactus fruit regarded in Greece that Professor Leotsakos assured me 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 hitherto known approaches the new hybrid species in quality or productivity. It appears that the cactus fruit is usu- ally 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 con- veniently refer to the fruit as a Cactus Pear, unless some more distinctive name should be suggested, THK CACTUS PEAR bi 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 artificial dyes that are now used so extensively, some of which are of doubtful wholesomeness. In Mexico the crushed fruit of the cactus after peeling and having the seeds strained out is sometimes cooked and dried and made into little loaves weighing from one to two pounds each. These cakes have a rich, sweet, honeylike flavor, to which the Mexicans are very partial. If carefully made, they are very appetizing and wholesome. Indeed, they constitute an impor- tant article of food, and are considered a luxury, having the qualities of a nutritious confection. Cactus fruit, indeed, is in high repute in many tropical countries, being in some regions re- garded as of especial value in renal diseases. Relatively large proportions of salts of mag- nesia, soda, potash, and lime in the fruit, in read- ily assimilable form, have been supposed to give it particular value, especially for residents of the tropics. The effect on the digestive organs is A GOOD SPECIMEN Some fruits of this size grow to the number of from twenty to fifty on a slab, and it is easy to see that the aggregate production is enormous. The amount of fruit grown on a single acre, under favorable conditions, may amount in the aggregate to more than thirty tons in a season. In this respect the improved cactus is unrivaled. THE CACTUS PEAR 19 also very favorable. Even the joints of the plant are made into pickles that, in the case of some varieties, are regarded as having a flavor equal to that of the cucumber. Most varieties, however, have a mucilaginous quality that is objectionable. This, of course, refers to the tissues of the plant itself, not to the fruit. It has been said that the cactus fruit in point _ of juiciness and texture is suggestive of a melon. Some people have compared its flavor to that of the Japanese persimmon or the cantaloupe. In other varieties the flavor suggests the raspberry. But, as already suggested, there is no standard of comparison that gives a clear conception of the taste of the fruit. The one conspicuous drawback is that the cac- tus fruit has been filled with seeds. In the case of some of the wild varieties, the seeds are large and especially hard, but even these are habitually swallowed by the people who eat the fruit. The improved varieties have seeds not larger than those of the tomato, although a little harder, and they may be swallowed with impunity. I have never known of anyone being injured by eating the cactus fruit in any quantity. It goes without saying that I have long had in mind to remove the seeds from the fruit of the perfected varieties of cactus fruit. Something A WELL-PROPORTIONED FRUIT This variety is perhaps nearly perfect in size and shape. It is not too large for comfortable handling, and it is of almost the best possible shape for com- pact storage during shipment. It has also qualities of flesh that highly commend it. ae > i ee > ee rae " = THE CACTUS PEAR 21 has already been accomplished toward this in the reduction of the size of the seed as just referred to, and in the best of the newer varieties the seeds have at last been wholly eliminated. The seeds are not collected at the center of the fruit as in the apple and pear and allied fruits, but are dis- tributed somewhat evenly through the pulp, after the manner of the seeds of the watermelon. | But as we have seen in connection with other plants, the seed is about the last thing that the plant is willing to relinquish, for the excellent reason that it is an all-essential part for the prop- agation of the species in a state of nature. But the cultivated cactus plants do not need their seeds, and as some of the newer varieties have re- linquished them, others will follow in due season. A specific account of the methods through which this was brought about, together with a detailed description of the origin of the spineless cactus itself is given in another volume. Eighteen thousand pounds of cac- tus fruit to the acre has been found to be a common crop on even the poorest soil, and twenty to thirty tons per acre of the improved varieties have been grown. Bais! ” hs a Hf vary . . re ; WAG a8 AYeet i The et + ove ee , SEY ARP AE “oR, es ¢ 1 ," 4 22 ag ite RTO: aa FRUITS WITH UNIQUE QUALITIES A CHINESE FRUIT witH GREEN FLESH —OTHER FRUITS NOTHER importation from the Orient that seems pretty certain to be welcomed here, is a plant indigenous to China, be- longing 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 23 24 LUTHER BURBANK at an altitude of about five thousand feet. He declares that the fruit is popular, and that efforts 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. The Chinese hairy plum, like its more promising relative the A. arguta of Korea, is dicecious; therefore it is necessary to have both staminate and pistillate plants, else no fruit is produced. The Korean species has borne fruit abundantly here for several years. 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 de- sired type, it can be multiplied indefinitely by dividing any part of the plant into sections and insuring conditions suitable for growth. Some of the plants of the genus are true climb- ers. Many of them, however, trail upon the ground. Those that climb are valuable for covering screens, arbors, walls, and low build- UNIQUE QUALITY FRUITS) 25 ings. The trailers are valuable for decorative purposes and quite often for their fruits. In Korea and Manchuria the long, slender vines of Actinidia arguta (the species with which my experiment began) are used for cordage. | | Other species are used in the manufacture of paper. My first introduction to the genus was through a number of large plants of Actinidia polygama received in 1904 from an American miner in Korea. The seeds already referred to were re- ceived five years later. The first fruit buds ap- peared 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 im- proving them. 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 ob- servations. 26 LUTHER BURBANK IMPROVING THE MyRrTLES 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 gigantic eucalyptus trees that grow to such im- mense size in Australia and California. True myrtles are mostly natives of the South- ern Hemisphere. ‘There are representatives of the tribe, however, that thrive in the tropical and subtropical 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 char- acteristic in the green-leaved variety. I have grown a beautiful variegated variety from the seed of the ordinary green myrtle. As a rule the UNIQUE QUALITY FRUITS 27 progeny of the “sport” thus produced tends to revert to the original type. And in 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 Chile and Patagonia, how- ever, which, although appearing very much like the common myrtle, bear fruit quite different in appearance, being pink, white, or yellow. The individual berries are usually as large as huckle- berries, 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. One of the Chilean and Patagonian species, M. Maytens, is used for timber, and grows to a height of fifteen feet, with a breadth of ten to twenty-five feet. ‘The branches droop grace- fully 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 of equal breadth. Another species that bears fruit when quite young, sometimes even in the second year, has FRUIT OF A CHILEAN MYRTLE This is another of the almost number- less tropical species with which we have experimented to develop new types of orchard and garden fruits. The berry of this Chilean myrtle has a pleasant odor and taste, and there is sufficient variation. to suggest the possibility of improvement through selective breed- mg. It may prove possible, also, to cross the plant with other myrtles, stimulating variation and giving further opportunity for selection. (One-third life size.) UNIQUE QUALITY FRUITS 29 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 brown or purple, sometimes slightly hairy, growing in compact drooping racemes like the currant. Some of the berries are of most excellent flavor, others woody or filled with seeds. Several thousand of the best seedlings from these exotic myrtles are now growing on my place, 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 crossing 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 30 LUTHER BURBANK may confidently expect in most members of this . family. _ Among these are plants of a group repre- sented in the eastern United States by the Flow- ering Raspberry, Rubus odoratus; in the cen- tral region by Rubus deliciosus of Colorado, and along the Pacific Coast from Alaska to southern California by the Thimbleberry, Rubus nutkanus. The eastern species is a handsome plant with large, deep, pink flowers that make it suitable for ornament. The western thimbleberry grows among the weeds of the lower hills and valleys, sometimes climbing high up the mountain slope, and in southern 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 Jarge, white flowers, flat, button- shaped red berries, and sweet, resinous, woody fragrance add to its attractiveness. The flowers of the thimbleberry 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 UNIQUE QUALITY FRUITS 31 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 thimbleberry 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. The Rubus deliciosus, the Colorado species, is ’ similar to the eastern one in most respects, ex- cept that the blossoms are white. All three species are almost thornless; the Colorado spe- cies practically wholly thornless, though the fruit of none of them is of any value. The hardi- ness of the thimbleberry 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 roseflorus, and the THE FRUIT OF THE STRAW- BERRY TREE This fruit looks good enough to eat, but is not. It would seem, however, that the fruit might be developed to have edible qualities. The strawberry tree is known to the botanist as Arbutus wunedo. There are several allied species of arbutus, and it is possible that, through hybridization, varieties may be produced that will have better fruits. Doubtless a good many of our cultivated fruits were less promising in their original wild state than this fruit of the straw- berry tree. 1—Vol. 5 Bur. UNIQUE QUALITY FRUITS 33 Wineberry, Rubus phenicolasius, 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-flower- ing 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 Wineberry 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, and the large, ample leaves, with their white undersurfaces, make the Wineberry a beautiful and attractive shrub. And although the experi- ments that have been made with it on my farms have not suggested great promise as to fruit pro- duction, 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 Wineberry must be regarded as possibly presenting oppor- 2—Vol. 5 Bur. 34 LUTHER BURBANK 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. FRvuit-BEARING SHRUBS Among: other plants with undeveloped fruit- ing possibilities are some shrubs of the heath family (Hricacee@), relatives of the rhododen- drons among flowering shrubs and the huckle- berry 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 considerably prized as an ornamental shrub. It is a small shrub, varying a good deal in size, but commonly growing to the height of about six feet. It bears berries that vary in size and color, but 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 UNIQUE QUALITY FRUITS _ 35 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, blossoms, and fruit are ornamental and attrac- tive. 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 numerous 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. My own experiments with the shrub have been confined to the raising of seedlings for ornamen- tal purposes. I observed that the Strawberry tree, like the Madrona, varies in size and some- times in shape and color of leaves and fruit. I am confident, therefore, that by special cultiva- FRUIT OF ONE OF MY GREATLY IMPROVED VARIETIES OF MOUNTAIN ASH Looked at individually, these fruits certainly suggest an apple. As an abundant bearer, the plant leaves noth- ing to be desired. It is only necessary to increase the size and improve the quality of the individual fruit. This has been done, and we now have a hybrid that produces fruit as large as crab apples. UNIQUE QUALITY FRUITS 37 tion 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 Hawthorn in particular is an extremely valuable shrub, and gives very great promise of the pro- duction of improved varieties of fruit through selective breeding, especially as it is one of the most variable shrubs. 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 opportunity for other workers in this field. Indeed, the work of devel- oping this fruit has made only the _ barest beginnings. 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. 38 LUTHER BURBANK The hawthorns are hardy shrubs or small trees, of vigorous growth. There are about seventy species available for crossing experiments, and some of them already bear fruit that is of good _ size and of excellent quality when cooked. 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 qualities of this responsive shrub? Largely by chance, certain plants have come under the attention of man, and thus have been brought about the familiar fruits of our or- chards, vineyards, and berry fields; who can predict the surprises which the orchards and vineyards and berry fields of the next generation will reveal? THE NEED FOR IMPROVING SMALL FRUITS AND SOME OF THE MEANS FOR MEETING It ITH 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 outlook, 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 even larger oppor- tunities for improvement with the berries and garden fruits than with the familiar orchard fruits, chiefly because the latter have been given a far larger share of attention by the horti- culturist. The large size and varied uses of apples, pears, peaches, and plums, in particular, have made them popular everywhere, and have caused a vast ' 39 40 LUTHER BURBANK deal of attention to be given them. So almost numberless varieties have been accidentally and sometimes purposely developed which meet the most varied requirements. But the small fruits have been the Cinderellas of the pomological family. Our own’generation was first to give them proper recognition, and it remains for our successors 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 it may be re- peated 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 sus- ceptible of general application. 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 throughout the world, during the last one hun- dred 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 IMPROVING SMALL FRUITS 41 nuts during the past twenty years has been par- ticularly remarkable, and they are in fact coming to be regarded as food staples, as they certainly should be. As an illustration, take the case of the straw- berry. This was the first small fruit commer- cially grown in the United States to any great extent. arly in the nineteenth century a few were raised in New Jersey for the market in New York City. Those who first engaged in this en- terprise soon found that, to keep up with the in- creasing 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 overproduction 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 con- sumed to-day in the United States to every cul- tivated strawberry that was eaten one hundred years ago. The consumption of the tree fruits, grapes, and other small fruits has increased in a some- what similar proportion. THE RESULT OF EDUCATION A cluster of one of my new hybrid mountain ash fruits. This is an exceed- ingly small cluster of a pear-shaped variety, which is acrid like the old mountain ash. Other varieties have enormous clusters of round crimson fruit of fairly edible quality. Thousands of young hybrids are yet to bear. ana ane etna IMPROVING SMALL FRUITS 48 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, cuttings, or roots of their favorite fruits; these were planted and orchards were grown. And in the course of events, when the families began moving westward, they usually selected seeds or more often trees of 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 pro- ductive and valuable were cherished. After this sifting process of the years, only a very few of the older fruits, in proportion to the number 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 older varieties of these fruits are slowly but surely being supplanted by still later productions. 44 °° LUTHER BURBANK 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 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 are new ones and 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 California, only a few of the eastern or Euro- pean varieties have been able to meet the con- IMPROVING SMALL FRUITS 45 ditions 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 Washington. There is a great field of usefulness open to the 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, others too warm, or too damp and with too fre- quent rains for certain fruits. It is the mission of the plant breeder to develop varieties that will withstand these conditions. What greater good can be accomplished than making exquisite fruits that will grow abun- dantly in sections of the country where none could be grown before? Curmate, DiseasE, AND HumaAN TASTES In creating new varieties to meet local condi- tions it is necessary to bear in mind not alone edible quality of fruit, but the constitution of the plant itself. 46 LUTHER BURBANK 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. 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. It is in this way alone that such diseases can ever 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 favorable 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 east- ern varieties, having become adapted to a moist climate, are open growers, bearing rather thin, delicate leaves. Such varieties are usually total failures when introduced in the arid Southwest. In developing a new fruit, the plant breeder must not only meet the exacting demands of IMPROVING SMALL FRUITS 47 nature, but also the exacting and increasingly complicated demands of the grower, the shipper, and the consumer; for together they constitute the jury that finally determines the value of his product. 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 in- sect pests; one that will flourish with little care, pruning, or other attention. The shipper and dealer are unconcerned about the characteristics of the trees, or their productiveness, but they are eager for an at- tractive fruit—large, bright-colored, handsome; in particular for one that is very solid—so hard that it can be handled like a cannon ball, which makes it a superb shipper. The consumer, on the other hand, prefers a reasonably tender, highly flavored, and easily digestible fruit. Unfortunately the consumer seldom obtains such a fruit unless it is grown near by or within his own community; for the ideals of the shipper and the dealer, at variance with his preferences, intervene between him and the orchardist. For instance, better varieties of strawberries for table use have been developed than can be 48 LUTHER BURBANK © found in any market; better in quality, aroma, and sweetness. The average consumer is never permitted to see them, or to experience their lusciousness. They are eliminated from the _ growers’ list of fruits, because they do not meet the demands of the shipper and the dealer. The consumer usually obtains the best that the producer, the shipper, and the dealer can furnish, under the conditions with which they have to contend; the fault is not theirs, but that of modern civilization. All this is mentioned merely to shia that varieties, the production of which is useful and profitable, are not necessarily the most desirable for food purposes. Consumers Must Bre EnucATED Yet the fault does not lie exclusivley with the dealers. When a new fruit is first introduced it is difficult for the people to become adapted or accustomed to it, if it possesses new and strange peculiarities and qualities that are not under- stood or appreciated. I have found that it is fully as difficult to adapt the people to a new fruit as it is to adapt a new fruit to the real wants of the people. New varieties that at first are condemned, may be accepted later as standards, and become IMPROVING SMALL FRUITS 49 practically the only ones grown. The same law seems to hold true with fruits as with new ideas - and new inventions in general; too often these are at first condemned, but if possessing gen- uine merit they are finally recognized and appreciated. I have met this experience in the introduc- tion of nearly all the new fruits that I have produced. It was ten years after the Burbank plum was introduced before people generally discovered that it was a valuable fruit. Now it is planted more widely than any plum on the globe, and thrives in almost all regions where plums can be grown. The excellent properties of the Wickson plum, now raised in most localities where plums are cultivated to any considerable extent, were for several years unrecognized. To-day it is ac- _ knowledged to be the best of the older shipping plums in existence, not only in America but in Africa, Australia, New Zealand, South America, and even in Japan. My Van Deman and Pineapple quinces were not very well received by some when first intro- duced; at present they are planted more than all other quinces in California, and everywhere acknowledged to be the best in quality, as well A CLUSTER OF THE NEW WHITE ELDERBERRIES This is a selected variety. There are several species of elders, and some of them show a tendency to vary—a trait that is always attractive to the plant developer, since tt gives him material with which to work. (About one-half life size.) ive Che ‘od IMPROVING SMALL FRUITS 51 as having all the other most desirable qualities in the highest degree, and in most of the Eastern States the first mentioned is considered the only variety worth growing, succeeding above all others even in the coldest climates. But little merit was seen in the Phenomenal berry when first introduced, but during the past few years until quite lately the demand for the plant could not possibly be met. When the Crimson Winter Rhubarb was first introduced, the rhubarb growers in California paid no attention to it, and for some time refused to plant it at all. More recently, fortunes have been made in California and other regions hav- ing a mild climate by its culture, and to-day it is practically the only rhubarb being planted in all mild climates. People did not understand its new and peculiar characters and qualities; time was required to educate them. The same might be said of the Shasta daisy and several scores of other plants, and nuts, flowers, fruits, and ornamental and forest trees and vegetables which have been produced on my grounds. I have learned through experience that no new fruit will be fully appreciated, or its quali- ties generally known or recognized, for at least ten or twenty years. 52 LUTHER BURBANK Corn, beans, peas, cucumbers, and similar plants can be tested in six months and accepted or rejected; but it requires years to test a new fruit so that its qualities may be thoroughly and generally appreciated. A RECAPITULATION OF METHODS We have seen that the adaptation of fruits to certain localities may be accomplished either by importation of plants developed elsewhere, or by producing the seedlings on the grounds, and selecting those that prove best adapted to the local conditions. In either case, a thorough study of each type of fruit in view of the needs and requirements of the location is absolutely necessary, in order to achieve success in the adaptation of the fruit. A section of country where strong winds pre- vail will require a fruit tree with compact form and of firm wood. In climates of brilliant sunshine the tree must be protected with an abundance of thick, heavy foliage. Some trees will not thrive in a dry soil; others cannot endure much moisture. And there may be differences as to these propensities among plants grown from the same lot of seed; and, indeed, from seeds produced by the same plant. IMPROVING SMALL FRUITS 538 Therefore not only the type but the individu- ality of the plant must of course be considered, — adapting it to certain conditions. If the quality of hardness in fruit is required, it may be attained through proper methods. . In regions where insect and fungous diseases thrive it is necessary to evolve fruit trees which are re- sistant to such pests; and there is no other way of reaching a satisfactory conclusion regarding their resistant powers than to grow them where they are exposed to their foes. All of this cannot be accomplished in a brief time. It requires the most persistent labor and unyielding patience. Any recognized “fruit quality” can be intensi- fied, almost any desired quality can be attained, through intelligent observation, selection, and patient waiting. But not without toil; nor with- out careful heed to such measures as will assure the cooperation of nature. Says Emerson: “The ripe fruit is dropped at last without violence, but the lightning fell and the storm raged, and strata were deposited and uptorn and bent back, and Chaos moved from beneath, to create and flavor the fruit on your table to-day.” Let the plant developer ponder and heed that saying, and realize that at best it is given him 54 LUTHER BURBANK not to create or overturn, but only to have a slight selective and directive influence in the great Scheme of Plant Evolution. FOUNDATIONS OF HEREDITY We have viewed in detail the story of the development of the different fruits, and have observed many anomalous products. We have witnessed the creation of new species, and have seen that rules applying to the hybridizing of certain forms appear to be quite abandoned in the hybridizing of others. But of course we know that the underlying principles are everywhere the same, and that seeming divergences in their application to dif- ferent species are but modifications of the same laws to meet varying conditions. The wise plant developer must be able to look beneath the sur- face and discover the underlying harmonies. Otherwise he will often make mistaken inter- pretations, and will perhaps give up an experi- ment when the goal was just within reach. Perhaps it may be helpful if now, by way of summary, we review in their broader outlines a few of the principles that have been illustrated by specific cases in the preceding volumes, and offer an added word of explanation that may be of aid to the general reader in clarifying his IMPROVING SMALL FRUITS 55 view of complex plant hybridizations, and to the plant experimenter in giving clews that — may prove advantageous in his work in the field. Let us recall, as the text of our first illustra- _ tion, the simplest case of plant crossing. When, let us say, a thorny and a thornless blackberry are crossed, the offspring are all thorny. But in the next generation a certain proportion of the offspring are thornless. A corresponding case is that of the ordinary blackberry crossed with the white blackberry. All the offspring of the first generation are black, but whiteness reappears among their descendants. | Let us recall, further, that the process of crossing consists essentially in bringing the nucleus of the pollen cell in combination with the nucleus of an egg cell. Also let us bear in mind a computation that we were able to make with the aid of the physi- cist, by which we were made aware that the germ cell itself is a highly complex structure with diversified component parts, each of which may be thought of as having as much individu- ality as any member of a developed organism. We saw that, even if we considered the indi- vidual parts or members of a germ cell to COLOR VARIATIONS IN THE CANES OF THE HYBRID BLACKBERRIES Not only is the leaf a guide to the kind of fruit which a plant will produce, but in many cases the stem or cane gives a reliable indication. With most berries it is the rule that the light stalk will produce the lightest colored berry—and the darker the stalk, the darker the * berry. From the variations shown above it will be seen that much time and expense may be saved by a careful examination of the young plants. Lose 8 tr IMPROVING SMALL FRUITS 57 number a thousand or more, there are avail- able many billions of atoms to make up each member. Let us then, finally, recall the teaching of the modern biologist, who gives us reason to believe that, just as each individual higher organism is produced by the union of two complementary elements, male and female, so there is union of complementary elements within the intimate structure of the ovule itself to form each new character. That is to say, using the accepted terminology, it is necessary in building up any character that is to be made manifest in the future adult organism, that there shall be a blending of two hereditary factors, which we may now think of as individual members of the germ plasm colony or organism. For example, there are factors of thorniness and factors of thornlessness in the germinal cell of the blackberry. There are color factors for blackness and for whiteness in the case of our other blackberry. It may be in any given case that the two factors united both represent thorniness, in which case the future plant will bear thorns. It may be, on the other hand, that the two factors both represent thornlessness, and in that case the future plant will be thornless. 58 LUTHER BURBANK Yet again there may be a union of a thorny factor with a thornless factor; and in this case, as we have seen, thorniness will prevail because, as we say—although, of course, our explanation only states the matter over again in another way—the thorny factor is dominant and the thornless factor recessive in this particular combination. Changing our terms to suit the case, the same principles apply to our black and white black- berries. And in each case, it will be recalled, the germ cell that bears only dominant factors will breed true to the dominant quality; the germ cell that bears only recessive factors will breed true to the recessive character; and the germ cell that bears the two conflicting factors will have prog- eny in which these factors are separated and reassembled in various combinations, thus accounting for the reappearance of the latent or recessive character. HEREDITY VISUALIZED All this is familiar to us and has been illus-; trated over and over again from practical cases in the course of our studies. And we have agreed that the really mysterious part of the entire process is the fact that the IMPROVING SMALL FRUITS 59 hereditary factors are able to combine with such certitude and grow and multiply and reproduce © themselves indefinitely. This part of the procedure is indeed mysterious and beyond the fathoming of the human mind. Yet perhaps it may be made to seem at least a little more tangible and explicable, even if not less mysterious, by an interpretation in which we are permitted for once to make use of the _ imagination. Suppose we imagine the existence within the complex structure of the infinitesimal germ plasm organism of a being of human intelligence, but of atomic proportions—an elf that has control of the hereditary factors, con- sidered now as material entities, and directs their use in the building up of a new organism, some- what as a human architect directs the use of ma- terial in the construction of a human habitation. Let us then assume that the material making up the nucleus of a pollen cell as it comes to the ovule of a flower and is brought in contact with the nucleus of the ovule, is in charge of one such elfin architect, and that the materials of the nucleus of the ovule itself are in charge of an- other elfin architect. The task of building the new structure that is to result from the union of the two nuclei devolves upon these two elfin architects jointly, They must work in cooper- 60 LUTHER BURBANK ation and their decisions will determine how the hereditary factors shall be combined in building the new organism. Suppose, now, that the particular case that is before us is that which arises when some colossal plant developer with his crude manipu- lations has succeeded in transferring a pollen grain of a thorny bramble that bears white berries to the pistil of a thornless bramble that bears black berries, and that the respective nuclei of pollen grain and ovule have come together. The elfin architects compare notes, inspect their respective blue prints and charts and tables of specifications, and set to work. For a time they get on very well. There are factors for general size and foliage and form of plant; for time of flowering and appearance of flower cells; for root system and shape of leaf and shape of future fruit, and a multitude of other details in regard to which there is perfect agreement. In all these cases the factor that A represents fits perfectly into the factor that B represents, and the work of building the future plant goes on apace. But presently, as they have built upward from the root and outward from the center, they come to the specifications for texture of stem. And here at once there is disagreement. IMPROVING SMALL FRUITS 61 Elf A finds that his specifications call for a thorny stem, but the factor that elf B represents _ calls for a smooth stem. And at once there is a discussion. “Whoever heard of a brier bush without pro- tective briers?’ demands elf A. “T have the honor to represent such a one,” says the other. “But the thing is a departure from all the traditions of good brier architecture,” insists A. “Moreover you cannot possibly fit the materials together without getting some brier material.” And this argument prevails. When the factors are examined, it is obvious that if they are put together the thorny fac- tor will overlie the thornless one, somewhat as a carved stone might overlie a smooth stone in a human dwelling. So it is admitted that the new organism must have a thorny stem. Now all goes well again until the two archi- tects come to the building of the future fruit. Character of flowers, time of fruiting, and gen- eral structure of the berry itself are all arranged. But just as the last detail was almost completed there is again a disagreement. It is discovered that A’s plan calls for a white fruit, B’s plan for a black fruit. THE STEM FINALLY SELECTED The direct-color photograph print _ opposite shows the stem of the first true white blackberry. By comparing its color with the color of other stems shown, it will be seen that the dark, purplish brown of the black Lawton has given way to the light greenish stem of the final white blackberry. The color of the stem, it should be understood, is only a guide to the color of the berry which is later to be produced. It does not form the basis of an absolute, fixed law, for outcroppings of old heredity some- times appear in the stem, but not in the fruit. The selection by the stem is, however, of sufficient certainty to warrant its use in such experiments as the production of the white blackberry. Where it failed as a guide in three or four cases, it succeeded in hundreds or thousands of cases. IMPROVING SMALL FRUITS 68 “Whoever heard of a white blackberry?’ de- mands B, turning thus rather neatly the argu- ment that the other elf used about the thorns. “The thing is ridiculous.” “I represent a white blackberry,” A replies, let us hope with dignity. “Well, there isn’t any way of blending white paint and black and keeping things white, is there?” B continues. And this argument is con- clusive. The two color factors are assembled, and it is conceded that the future plant will bear black fruit. The black pigment overlies the white like a double coat of paint, and a black fruit is provided for. When the elfin architects have finished their task, then the factors representing the materials of the two germ cells have all been satisfactorily paired, and provision has been made for a future bramble that will have a thorny stem and will bear black berries—a plant that is unlike either parent, although built of no material except factors drawn from the two parents. Recall, however, that the factors for thornless- ness and for white fruit were not eliminated. They were only overlaid by the opposing factors. They go forward in the germ plasm, each pair of factors being constantly multiplied through division in the mysterious way that characterizes 64 LUTHER BURBANK living matter, so that for each factor that entered into the original structure there are now multi- tudes of factors. And in the next generation, when new pairs of elfin architects are making their plans, it will ‘be possible to reassort the materials (in building a large number of new structures that we call offspring of the second generation), making some combinations that will include two smooth- stemmed factors and two white-fruit factors, and thus giving us a certain number of seedlings of this second generation that will have smooth stems and will bear white berries—which chances, perhaps, to be what the crude human experi- menter is seeking. THE ARCHITECTS ON STRIKE But now let us attend to a case in which a more complex hybridization was made; that, let us say, in which the pollen of an apple was brought to the pistil of a dewberry. Now we must call attention to a feature that | we have ignored heretofore—the segregation of body plasm and germ plasm at an early stage of the union. The coming together of the two germ plasms gives a stimulus to growth. The berry develops, and a drupe is formed that is like a dewberry, IMPROVING SMALL FRUITS 65 because the body plasm of the dewberry is acting as carrier. That is to say, the dewberry is the pistillate parent. The elfin architects in a single ovule get to- gether. They separate out the body plasm, and, although there is conflict, it appears that the material will permit the building of a root and stem and leaf system that will answer after a fashion—though a sad departure from tradition. A big rambling bush that will try to ape both dewberry and apple tree will result. — But in the matter of the architecture of the germ plasm for the new organism through which the race is to be perpetuated, difficulties arise at the outset that are almost disheartening. There has been trouble enough in getting the factors together to make any sort of stem and leaf and flower. But all this was nothing com- pared to the difficulties that arise when they get to the fruit. “Specifications for fruit,” says A, consulting his blue print: “A big, pulpy fruit, about four inches in diameter, called an apple.” “Not at all,” cries B, consulting his own blue print. “The fruit is a small berry about an inch long, with many drupelets each having a seed at its center—in short, a blackberry.” 8—Vol. 5 Bur. 66 LUTHER BURBANK How can two elfin architects hope to harmonize materials like that? It is like getting together two human architects to combine materials for a habitation and finding that the material one has to offer for the house are blocks of stone four feet square while the other has only pebbles. And as the conference goes on, the points of discrepancy become only the more apparent. All the differences that are manifest between a blackberry bush and an apple tree, and between an apple and a blackberry—together with a mul- titude of intimate distinctions that the crude human senses cannot fathom—are represented by factors that obviously cannot blend. So, after studying the matter over and wrangling about it till their heads ache, the elfin builders give up the thing as a bad job. Their germ factors lie in separate piles unas- sembled and incapable of being assembled; and the result is that no provision will be made for fruit in the future plant. In other words the plant will be sterile, and that particular double stream of germ plasm will cease to be per- petuated. | By Way oF SUMMARY This, then, is what may be imagined to occur when there is too great difference of materials. It may be left to the reader’s imagination to make IMPROVING SMALL FRUITS 67 for himself a picture of the various activities of the elfin architects in those cases where the diver- sity between the different hereditary factors 1s greater than that between the two kinds of black- berries, but less than that between the apple and the dewberry. We saw in such cases as that of the Primus berry and the Sunberry that when the two germ plasms were at just a certain stage of divergence the resulting hybrid presented a compromise of characteristics. We may suppose that the elfin architects in the germ plasm are in such a case to be compared with human architects, one of whom, let us say, presents blocks of stone as the chief building material while the other presents bricks. Stone and bricks cannot be blended, but they may be variously combined, for example, placed in alternate layers, to make a structure that is neither a stone house nor a brick house, although it is a house built of both stone and brick. In the same way the Primus berry is neither a blackberry nor a raspberry, although its com- ponent hereditary factors are all either black- berry or raspberry factors. | But we need not attempt to carry the illustra- tion further. The reader who has followed it may make his own application, in reviewing the facts 68 LUTHER BURBANK as to the various results of hybridizing species more or less closely related that have been de- tailed in the preceding chapters. To some readers the entire illustration of the elfin architects may seem whimsical. But it is presented in all seriousness in the hope that it may serve a useful purpose. Not that I would for a moment be understood as suggesting that any such infinitesimal creatures with human in- telligence are really domiciled in the germ cell. But to personify thus the inscrutable forces through which the building together of the hereditary factors is brought about may serve to give tangibility to the forces of heredity, and to help the reader to memorize the facts already presented, and gain clearer insight into the prin- ciples that underlie them. _It may chance that such a personification will enable the plant: developer to see a little more clearly into the nature of the phenomena that are presented before his eyes when two plants are hybridized; and that he may thus be enabled to interpret the phenomena in a way that will be to his practical benefit. As elsewhere pointed out, the incorrect interpretation of the early results of a hybridizing experiment may put the experi- menter off the track and Jead him to give up an effort which would have led to complete IMPROVING SMALL FRUITS 69 success had it been carried forward another generation. But, in any event, whether or not the reader finds the elfin architects of the germ plasm an aid in his interpretation of the phenomena of heredity, let the would-be developer of new fruits or the improver of old ones, bear in mind, as the Jast word that experience can offer on the sub- ject, the principle that progress must be sought through the careful selection of types that vary in the direction of desired progress; and that in a vast majority of cases such variation may be brought about, and in a sense directed, through hybridization. The successful plant developer must be able to look beneath the surface of his plants to discover and utilize the underlying harmonies. Fuh? F3TRS te ee Vy en ears fastbite . ry
specialization is so great that there is small pros-
pect of securing a useful form by bringing them
together.
Such a development is not impossible, however,
but it would certainly be difficult to fix the new
type after it had been produced.
My own experience with the cabbage tribe was
chiefly gained in the early days of my experi-
mental work, half a century ago, when I found
that it was easy to cross the cabbage with the
cauliflower and with other members of the tribe;
that, in fact, it is necessary to grow them quite
a distance apart in order to keep the seeds pure.
But the hybrids produced were all what we were
accustomed then to describe as mongrels. Some
of them had small cauliflowerlike heads of in-
ferior quality.
At the time when these experiments were
made I did not fully understand the impor-
tance of the second generation, and have never
found time to take this ine of experiment
up again.
I had good success then, however, in crossing
the purple-leaved cabbage with other varieties of
cabbage, developing thus a purple cabbage with
a very large head. Though larger, they were
somewhat less dark in color than the parent
stock.
COMMON GARDEN PLANTS 121
My work with the turnip has not extended
beyond: the stage of experimental crossing as
with the cabbages, which led to no prospect of
useful results. With the radish, which might be
described as a dwarf turnip, much work has been
carried along the line of selection, without
hybridizing.
There are enough variations among the seed-
lings of any given variety of radish to afford
ample opportunity for selection as to form, color,
and qualities in general.
In the. course of the experiments a dozen or
more of the most popular kinds of radish were
used, the principal aim being to get the roots very
uniform and smooth, all developing at the same
time, instead of at different times as most rad-
ishes now do; and all of uniform color.
Another object was to develop varieties with
the smallest amount of foliage that would be
adequate to build up the roots quickly under good
conditions. __
Also attention was given at one time to the
flavor of the radish, in developing a sweeter pun-
gency for which the vegetable is relished.
As just noted, all the radish seed used in these
experiments proved exceedingly variable; and
even those that were selected and reselected per-
sistently for several years showed a tendency to
ANOTHER OLD FRIEND
The radish..can claim no such
economic im portance as the beet has now
attained; but it is perhaps even more
universally distributed in the gardens of
the world. The specimens here shown
illustrate the wide variation of form
among the different varieties that have
been developed through selective
breeding.
COMMON GARDEN PLANTS 128
reversion. But this variability, while it is annoy-
ing to the practical gardener, should give the
radish added interest from the standpoint of the
plant developer. The amateur who wishes to
experiment with this species can begin with
plants grown from any good seed that he may
secure. He might then hybridize these plants
with seed of a Japanese or Chinese variety.
The radish is supposed to have originated in
China and the vegetable is still very popular in
the Orient, where besides being eaten raw it is
pickled, dried, and preserved in various ways
_ somewhat as we preserve fruits.
ONE OF THE ORIENTAL RADISHES
The Oriental radish is of large size and may be
grown readily in a soil adapted to radishes in
general; that is to say, a white, clean, sharp sand,
which should be fertilized with chemical fertilizers
only. The plants should have plenty of moisture
and sunshine, thus being urged to rapid growth.
They are much more subject to disease and liable
to become pithy or hard when grown in rich soil
than when grown in the sand, and are also of less"
satisfactory flavor.
There is little doubt that by crossing the
Oriental varieties with our common ones some
interesting variations would be produced that
124 LUTHER BURBANK
might lead to the development of new varieties
not without importance.
SOME OBSTINATE Root BEARERS
In marked contrast with the members of the
crucifer family, with their extraordinary tend-
ency to variation, are the two familiar members
of the garden family that are most prized for
their roots, the carrot and the parsnip. . For these
have assumed a characteristic shape from which
they show very little tendency to vary, and even
under persistent cultivation have held very true
to their type. |
The plants are closely related, and both are
descended from wild forms that are poisonous.
Moreover the cultivated species themselves, if
allowed to hold over until the second season, may
in some cases develop.a poisonous quality. But
as ordinarily grown from the seed and used the
first season, they constitute wholesome vegetables
of deserved popularity.
My work with the parsnip has been confined to
the attempt to develop a race having roots that
are smoother and of a broader or more compact
form. But this was found to be a thankless task,
as the roots tend to reach downward in spite of
all the education that could be given them. It is
a persistent quality that the plant seems very un-
COMMON GARDEN PLANTS 125
willing to give up. In this the parsnip shows its
retention of the habit of its wild ancestor. The
carrot also is not altogether free from its wild
instinets, and will pretty readily revert to the
wild state.
I have experimented with the wild carrot,
which has a long, hard, slender root, and found
that this could be brought back to the production
of what might be called a civilized root.
Color may be added to the carrot root or taken
away from it by selection through successive
generations.
This is quite what we might expect. iedien we
consider the difference in color between the roots
of the carrot and the parsnip, which in their wild
forms are very closely related.
There is opportunity for some one to adie.
take the improvement of both parsnip and carrot
as to the quality and shape of their roots, and
such experiments might very likely prove suc-
cessful if carried out persistently, notwithstand-
ing my own failure to produce marked modifica-
tions in this regard. The flavor of the carrot
could be improved, probably without any great
difficulty.
SALSIFY OR OysTER PLANT |
There i is another root that offers a challenge to
the plant developer somewhat as do the parsnip
PARSNIPS
Not even.a tyro at gardening or
botany needs to be told that the parsnip
18 own cousin to the carrot. It is equally
obvious, however, that the two belong to
quite different species. The parsnip
has been rather neglected by the scien-
tifie plant developer and there is abun-
dant opportunity for its improvement.
COMMON GARDEN PLANTS 127
and carrot, by the very fact of its obstinate
resistance to any change. This is the plant
called Salsify, usually known to gardeners as —
the oyster plant or vegetable oyster. It is a
biennial plant having long, slender, light gray
roots.
There is only one greatly improved horticul-
tural variety. This is known as the Sandwich
Island Mammoth. It is fully twice as large as
the ordinary salsify, which it otherwise closely
resembles. |
I have worked with the Sandwich Island Mam-
moth with particular reference to improving the
smoothness and plumpness of its root. But it
was found to be one of the most stubbornly fixed
of plants. This is quite what might be expected
of a plant that has only one species under culti-
vation. We have elsewhere seen that the plants
that have many species are the ones that tend to
vary.
There are, however, two or three wild mem-
bers of the tribe, one known as the Spanish salsify
and another as the black salsify, a native of
Europe.
It is possible that these might be used to
hybridize with the ordinary and the Sandwich
Island species, and that the element of variability
might thus be introduced.
128 LUTHER BURBANK
Possibly through selective breeding, based on
such hybridizations, new varieties of salsify might
be developed and the plant might thus conceiv-
ably be made to occupy a much more important
position than it does at present among garden
vegetables.
PEAS AND BEANS AS PROFIT-
ABLE CROPS
IMPROVEMENTS WHiIcH PROMISE MucH
VERY good illustration of directive
plant breeding is furnished by the case of
the Empson peas.
This was a case in which I received an order
for the development of a new variety of pea that
would fulfill certain definite specifications, some-
what as a manufacturer of cloth or of electric
dynamos or of machinery of any sort might re-
ceive an order for a new product to meet a special
condition.
It is gratifying to record that I was able to
meet the specifications, and “deliver the goods,”
as a manufacturer might say, as accurately
and satisfactorily as if the product had been
one to be turned out by factory machinery
instead of by selective breeding of a living
plant.
_ The specifications were these: A productive
variety that shall mature all its pods at the same
129
5—Vol. 5 Bur.
130 LUTHER BURBANK
time; bearing individual peas of reduced but
uniform size, sweet, and of superior flavor.
Here, it will be observed, there are several
quite distinct characteristics to be borne in mind.
Perhaps the most important, or at least the ones
most difficult to attain and fix, were the uniform
time of ripening and uniform size of the peas
themselves. How these difficulties were met will
be detailed presently.
First, however, let me tell just how it came
about that the order for peas having just these
specifications was received.
MANUFACTURER AND PUBLIC
The order was given by a large canning fac-
tory, located originally in Colorado, but now
having branch factories in other regions, with
capacity to handle in the aggregate forty-six
thousand cans of peas per hour.
The head of this company is a man who has
made a study of his public, and who aims to give
the public what it wants. He discovered that
there was a demand for canned peas of very
small size. This had come about, probably,
through the example set by the French, who can
the peas when they are half grown, at which
stage they are sweeter and more tender than
when more fully ripened.
PEAS AND BEANS 181
The American public developed a liking for
these small peas, and a willingness to pay more
for them than for the larger ones, but no Ameri-
ean canner could profitably duplicate them in size
and quality.
The American canners are themselves con-
vinced that peas of medium size are really better;
and they were desirous that the public should
have what it wanted. |
So it came about that I received a letter from
the management of the canning company asking
me to undertake the work of developing a pea
_ that would meet the specifications as to size,
and yet would mature in such quantities and
with such uniformity that there would not be
great loss in handling, as there would be if
the pods matured as then grown at different
times.
The reason that this specification is imperative
is that peas for canning, according to modern
methods, are not gathered by hand. Indeed they
are not touched with the hand at any stage of
their existence, even in planting. The crop must
be ready all at once, because the vines themselves
are harvested. A machine is drawn along the
rows cutting off the roots about an inch under-
ground, and raking four rows together in a
windrow.
132 LUTHER BURBANK
Cutting below the ground keeps the peas fresh
and also insures getting the entire crop.
A wagon immediately follows, gathering up
the pod-laden vines like a load of hay, and
hauling them to the factory, where they are
fed by machinery into a sheller, which consists
of two big cylinders with vulcanized rubber
cups on their surfaces, so arranged that the air
pressure splits the pods open without crushing
them.
The peas roll down an inclined plane with per-
forations of different sizes, and are thus auto-
matically sorted into five grades, just as oranges
of different sizes are sorted in California. The
peas all fall into clean running water and are im-
mediately canned without being touched. It may
be interesting to add that a factory of this type
has a record of putting canned peas on the shelves
of the grocer within two hours of the time when
they were growing on the vine in the field.
Peas in cans under these circumstances may be
fresher and better than those purchased in the
pod usually are.
These details as to canning obviously have no
direct bearing on the methods of the plant devel-
oper. But they explain the specifications that
were given along with the order for the hew
variety.
PEAS AND BEANS . 133
In attempting to meet the specifications, 1
followed the methods of rigid and systematic
selection. There was no occasion for cross-fer-_
tilization, as the peas were of good quality, and
showed enough variation as to all of the desired
characteristics to offer material for selection.
My plan was to pick out in successive genera-
tions the vine that came nearest to meeting specifi-
cations as to number of pods, uniformity of ripen-
ing, and small size as well as uniform size of the
peas themselves.
It was necessary, as in other experiments of a
similar kind, to watch the individual plants,
selecting the very best individual plants, and
harvesting them by themselves, counting the
pods and counting the peas, and making careful
record of results. :
Fortunately it is possible with the pea to raise
two crops in a season. Thus I was enabled to
progress very much more rapidly than otherwise
could have hoped to do. We could do two years’
work in one.
So we were able to deal with six generations
of peas in three years. And yet by that time the
undesirable qualities had been so systematically
excluded and desirable ones so persistently
sought for that the educated pea vines fulfilled
the specifications exactly.
COWPEAS UNDER CULTIVATION
This picture shows another form of
leguminous plant that has become
popular in comparatively recent years.
It is of solid and compact growth, and
makes a remarkable cover or forage
crop. Like the other legumes, its
product is rich in nitrogen, a fact long
recognized but the explanation of
which has been given only in
comparatively recent years.
Sine coon
PEAS AND BEANS 135
I find in my files a letter bearing date of
February 29, 1908, that may be quoted here as
summarizing the results of the experiments: _
“By express to-day,” I wrote, “I send you all
the peas raised from the one best of all my selec-
tions. This one is the one which produced the
most peas to the pod, the most pods to the vines,
had the most uniformly filled pods, and in all
respects was the most productive and best; on the
whole, the best pea, taking quality, quantity, and
everything into consideration, which I have ever
seen. They are fifteen per cent smaller.on the
average. One other thing which I have added to
them is that they are sweeter than the pea which
you first sent me. They all came from one single
vine which was the best in all respects and the
seed has been reselected through six generations.”
MULTIPLYING THE NEW VARIETY
Of course, the selected pea, as thus produced,
existed only in small quantities. But it had been
fixed as to type and could be depended on to
breed absolutely true. It was necessary, how-
ever, for the company to multiply the seed for a
number of years before there was enough of it in
existence to use for the purposes of the canner.
By growing the crops in California, however,
where from two to four crops could be raised
136 LUTHER BURBANK
each year, and by using the entire product for
the seed in successive years, the progeny of the
single vine from which I developed the new
variety had been multiplied by 1912 so that
material enough was at last in hand to plant
hundreds of acres and supply the cannery with
the small, sweet, uniform-sized and uniform-
ripening pea that was desired.
I have cited this case in detail, not because it
is of exceptional importance in comparison with
hundreds of others of my plant developing ex-
periments, but simply because it illustrates the
possibility of developing quite rapidly a par-
ticular plant to meet a specific commercial need.
But to understand fully the conditions met
even in this single experiment, it is necessary to
add that I did not confine attention to the pro-
duction of the single variety just described, even
in the line of experiments that were undertaken
specifically for the purpose of producing that
variety. On the contrary, while scrutinizing the
vines for small peas of uniform size, I kept
vigilant watch also for other vines that varied
in the opposite direction.
Peas MOopIFIED IN OTHER DIRECTIONS
By carrying forward several serfes of selec-
tions at the same time, a number of varieties
PEAS AND BEANS 137
were simultaneously developed that differed
widely both from one another and from the
original stock. |
I found, for example, in the observation of
the early generations grown from the seed, that
some plants would produce four or even five
times as much as others. This habit of pro-
ductiveness was carried to the next generation
with a good deal of certainty. So it proved
possible, by careful selection, in three years, to
develop new forms of peas which produced regu-
larly four or five times as much as the average
production of the parent form.
Of course, this quality of productivity was
combined with the various other qualities and
was manifested in the perfected pea that was
delivered along with the letter just quoted.
But there were other qualities which obviously
could not enter into the combination, because of
variation in exactly the opposite direction from
the one in which we were developing the little
canning pea. Thus, for example, one variety
instead of having small peas had exceptionally
large ones. Another variety produced lozenge-
shaped peas. These seemed to be unusually
sweet, and as they were also among the most
productive, I made two strains of this selection
alone. One of these is a very large lozenge-
188 LUTHER BURBANK
shaped pea, circular, and indented on the flat-
tened sides.
Both are practically fixed, coming true to type
from seed.
In fact, by having different ideals and bear-
ing them in mind all.along, I developed four
strains of new varieties that the canners were
glad to purchase, in addition to the one that they
had specifically ordered. And all this was done,
as just noted, by selection, without the aid of
hybridizing experiments.
It should be explained that the pea is nor-
mally self-fertilized, so that there is the closest
inbreeding, and it is therefore relatively easy to
fix a type. Moreover the pea is a very pliable
plant, producing new varieties with little care
and labor as compared with many other plants.
Although I have devoted much less time to it
than to many other plants, I have developed
numerous varieties that are specially modified
for color, for productiveness, for size, for quality,
or for resistance to mildew and other affections.
And other experiments are under way that will
probably lead to still further developments.
MENDEL’s FAMous EXPERIMENTS
Although much may thus be accomplished
with the pea by mere selection, it should be re-
PEAS AND BEANS 1389
membered that this plant offers exceptional
opportunities also for development by hybrid-
ization. In particular it should be recalled that
the extraordinary experiments through which
the Austrian monk, Mendel, made the discov-
eries that have created such commotion in the
biological world, were made with the common
garden pea.
Reference to these experiments has been made
more than once, but it will be worth while to
examine them a little more in detail in the pres-
ent connection.
_ The discovery that Mendel first made, to
which we have already referred, was that certain
qualities of the pea are grouped into very con-
spicuous pairs.
His investigation led him to believe that there
are at least seven differentiating characters that
could be relied upon to reproduce themselves
with certainty in the offspring of the pea. These
characters, which he came to speak of as “unit”
characters, are the following:
(1) The form of the ripe seed, which
may be roundish, either with or without
shallow wrinkles, or angular and deeply
wrinkled.
(2) The color of the reserve material in the
cotyledons or little leaves that first appear when
140 LUTHER BURBANK
the seedling comes out of the ground; the colors
being pale yellow, bright yellow, orange, or
green.
(3) The color of the seed coats; white, as is
usual in peas with white flowers, or gray, gray-
brown, leather-brown, with or without violet
spots, etc.
(4) The form of the ripe pods, whether in-
flated or constricted or wrinkled.
(5) The color of the unripe pods, whether
light or dark green or vividly yellow, these colors
being correlated with colors of stalk, leaf, vines,
and blossoms.
(6) The position of the flowers, whether axil-
lary or terminal.
(7) The length of the stem of the plant itself,
whether tall or dwarfish.
It is obvious that in each case the different
qualities named are antagonistic or mutually
exclusive. The seed cannot be at the same time
round and angular; it cannot be at the same time
smooth and wrinkled; cotyledons cannot be at
once yellow and green; the pods cannot be at
once inflated and constricted. And as each race
of peas, when inbred, holds true to its type, there
was opportunity to observe the effects of cross-
ing the different races in relation to these differ-
ent fixed characters.
PEAS’ AND’ BEANS 141
The results Mendel obtained have already
been outlined, and more than once referred to’in
this and in previous volumes. | 7
It will be recalled that, as regards the various
pairs of antagonistic characters, he found that
one or the other proved prepotent or dominant
in the first generation; but in the second gener-
ation (when the first generation hybrids were —
inbred) the submerged or recessive character
would reappear in one case in four on the
average. Thus he found that in the pea tallness
of stalk is dominant to shortness of stalk; that
-yellowness of seed is dominant to greenness of
seed, etc. This was demonstrated by the fact
when a tall pea was crossed with a short one all
the offspring were tall, but one-fourth of the
offspring of the second generation were short.
Similarly when a pea with yellow pods was
crossed with one having green pods, all the
plants of the first generation had yellow pods;
but one-fourth of their offspring of the next
generation had green pods.
THE SEGREGATION OF CHARACTERS
A second very important feature discovered
by Mendel was that the different antagonistic
pairs of qualities are transmitted quite inde-
pendently of one another.
142 LUTHER BURBANK
For example, the relations of tall and short
peas, blended in heredity, are quite independent
of the question of yellowness versus greenness
of pod. So observation may be made as to two
or more qualities in the course of the same
experiment. .
Thus, if a tall variety of pea that bears green
pods is crossed with a short variety bearing
yellow pods, all the offspring will be tall peas
with yellow pods—therefore unlike either parent.
But the offspring of the next generation will
such a recurrence of each of the recessive factors
in one case in four, so that one-fourth of them
will be short and one-fourth will have green
pods. But it appeared, so far as Mendel could
determine, to be a mere matter of chance—like
the throwing of dice—as to the exact number of
cases in which shortness of stalk would be com-
bined with the bearing of yellow pods.
PAIRING THE FACTORS
If we assume—as Mendel finally came to do
—that each of the different qualities about which
we are speaking is represented in the germ plasm
by a definite mechanical factor which must be
paired with another factor, either like or unlike
itself, in order to stimulate the development of
the character it represents, then at least a pro-
PEAS AND BEANS 148
visional explanation of the observed facts might
be found in supposing that a dominant factor
when mated with a recessive one hides or ob-
secures the recessive one in that particular com-
bination, but does not eliminate it.
_ And when the factors are again mixed to pro-
duce a new generation, they are still equal in
number, and if we think of the factors as tan-_
gible things—let us say like black or white
checker men—it will appear that if equal numbers
of each are mixed together and taken from a bag
in pairs at random or blindfold, it will come
about, according to the mere theory of chances,
that one time in four two of the white checkers
will be paired.
This accounts in a crude and mechanical but
on the whole a rather satisfactory way for the
appearance of the recessive character—say short-
ness of vine or greenness of pod—in one indi-
vidual out of four of the second-generation
progeny.
And when we apply the same reasoning to the
case where two pairs of factors are under con-
sideration—tallness versus shortness, and yel-
lowness versus greenness in the present case—
it appears that each pair of factors will follow
precisely the same law, so that one in four of the
second generation descendants will be short and
144 LUTHER BURBANK
one in four will be green; but that the same law
of chances, applied to this more complex case,
gives us only one case in sixteen in which two
factors for shortness are combined with two
factors for greenness in the same group.
In other words, one pea in sixteen descended
in the second generation from the tall pea with
green pods and the short pea with yellow pods
will have a short vine and at the same time will
bear green pods.
This will be a new variety. It has no new
quality, but it has the old qualities in a new
combination.
Extending the experiment one stage further,
Mendel found that the second-generation peas
that show the recurrence of the recessive factor
will breed true to that factor. And this, again,
is quite what might be expected on the theory
just outlined. For the pea that contains two
factors for shortness will obviously have no pro-
pensity to grow tall, and the pea that contains
two factors for greenness of pod will obviously
have no capacity for the production of pods
other than green.
So our short pea vine with its green pods,
although it represents a new variety, which, for
the sake of argument we assume never to have
existed before; and although it appeared sud-
PEAS AND BEANS 145
denly as what might be considered a mutation,
yet is fixed from the outset, and will breed true,
and constitute an established variety.
All this we have referred to in earlier chap-
ters, and we have seen many illustrations of this
so-called Mendelian inheritance in the case of a
good many of our plant developments—the
white blackberry, for example, the stoneless
plum, and the thornless blackberry among
others. But it seemed worth while to make spe-
cific reference to Mendel’s work with the peas,
in the present connection, in particular because
this work doubtless represents the most impor-
tant thing that has been done with the pea at
any recent stage of its development.
PEAS VERSUS BEANS
It was perhaps fortunate that the Austrian
monk chose the pea for his investigation rather
than the bean, for, notwithstanding the fairly
close relationship between these two, there is a
rather marked difference between them as to
their practical response to the efforts of the plant
developer. Perhaps because the pea has been
cultivated under varied conditions, and selected
for a wide variety of qualities, this plant shows a
marked tendency to vary, suggesting in this
regard the evening primrose and Godetia, and
SHOWING VARIATION IN
BEANS
The bean is even more variable than
the pea; and as there are many species
and varieties under cultivation, so there
1s almost endless opportunity for de-
veloping new varieties. Here are some
samples, all of which developed without
crossing from a single variety.
PEAS AND BEANS 147
the new varieties are often practically fixed from
the outset. |
With beans it is less easy to trace and classify
the opposing “unit” characters, and in practice
it is often necessary to select rigidly and con-
tinuously for five or six successive generations
_in order to fix a new variety.
An illustration of the complexities that may.
result when beans of different kinds are crossed
was given me at the outset of my work as a plant
developer.
CrossInNc THE PoLE BEANS
One of my first experiments in hybridizing
was made by crossing the horticultural pole bean
or wren’s egg with another variety of pole bean
known as the red cranberry bean.
The hybridization was effected with some diffi-
culty, inasmuch as only one blossom in perhaps
fifty responded to cross-pollenization and a part
of the offspring seemed to lack vitality, as I suc-
ceeded in bringing but one plant to maturity.
But this was in some respects the most astonish-
ing bean plant that I have ever seen. It bore
long black pods and the beans within them were
as black as ink. |
Yet one of the parent beans had produced a
crimson pod with a red seed, and the other a
148 LUTHER BURBANK
crimson and white striped pod, with red and
white striped seed, and no trace of blackness.
Here, it-will be seen, there was no such sharp
differentiation of the color factors for pod or
seed into opposing pairs, with dominance in one
and recessiveness in the other, as was shown by
the peas in Mendel’s experiments. On the con-
trary, the union of red beans with red and white
striped ones produced something totally unlike
either—namely, a jet black bean.
But in the succeeding generation the offspring
of the black bean showed a breaking up into new
groups of characters suggestive of Mendelian
heredity. Some of them were black, some red,
some speckled, and some white. There were
corresponding variations also as to size and shape
of the beans, some being large and some small,
some round and some. flat. And there was
marked diversity in time of ripening.
As to the vines themselves, the original hybrid
showed the enhanced vitality that commonly
characterizes the offspring of rather widely sep-
arated parents. The original first generation
vine (which bore the black beans) grew to
enormous size, outstripping either parent by
eight or ten feet, and rivaling the growth of a
hop vine. The vines of the second generation
were as diversified as the seed.
‘PEAS AND BEANS 149
Some of them were long and vigorous, while
others were extraordinarily dwarfed, some being
so stocky as to grow pods that almost immedi-
ately touched the ground and were obliged
to’ bend back like hairpins to find room for
growth. There were corresponding variations
in size, shape, and color of the leaves. —
All this suggests that the beans originally
hybridized were themselves of very mixed ances-
try, and that a large number of hereditary traits
that had been blended in them were permitted to
make themselves manifest through the recom-
bination and segregation of hereditary factors.
‘The reader cannot fail to note a similarity
here between the results obtained and those that
were obtained when the Persian walnut and the
California black walnut were hybridized. There,
as in the case of the beans, the immediate off-
spring were of gigantic growth, but the progeny
in turn showed both giants and dwarfs.
The interest of both cases (and of a number
of other allied ones that will be recalled) in
illustrating the Mendelian principle of the seg-
regation of recessive factors for size, leading to
the production of a race of dwarfs, will be
obvious. .
Another hybridizing experiment with the
beans, also undertaken in the early days of my
150 LUTHER BURBANK
investigations, brought together two varieties
that are even niore distantly related.
Crossinc Potz BEANS AND LIMaAs
In this experiment I hybridized the horticul-
tural pole bean, or “wren’s egg,” with the lima
bean. It proved exceedingly difficult to make
this cross, but after many fruitless efforts I at
last succeeded in securing a single pod con-
taining four sound beans by using the pollen
of the lima on the pistil of the horticultural
bean.
When these seeds were planted, in the sum-
mer Of 1872, a very strange result was observed
——the beans themselves had in all respects the
form, size, and appearance of the horticultural
bean, but when their sprouts broke ground it
was at once observed that the upper part of
their cotyledons (varying from one-quarter to
three-quarters of their length in different speci-
mens) were indubitably those of the lima bean;
while the lower part of each cotyledon was pre-
cisely that of the horticultural pole bean.
These parts were connected with serrated
edges, which at last separated, allowing the lima
bean part to drop away. Such separation, how-
ever, did not occur until the vines had made a
foot or more of growth.
PEAS AND BEANS 151
The cotyledons on each side were divided
uniformly in every case. |
Thus the influence of the pollenizing parent
was very markedly shown in the young vines
from the moment of their appearance. But after
the cotyledons had fallen, all evidence of the
paternal parentage of the plants disappeared.
The vines did, indeed, show very unusual vigor |
throughout the season, this, of course, suggesting
their hybridity. But as to appearance and char-
acteristics in general, with this exception, they
were essentially horticultural pole beans like
their maternal parent.
The experiment was carried on for several
succeeding generations, but the progeny showed
no reversion to the traits of the lima bean. The
characteristics of the pole bean had seemingly
been prepotent or dominant to an overwhelming
degree. ,
This, then, would appear to be another case
in which a new race was formed in a single gen-
eration by the mingling of two widely divergent
racial strains. These hybrids of the lima and
the pole bean may be compared, in that regard,
to the Plumcot and the Primus berry, to name
only two of the various allied instances that have
come to our attention. This is what I call a seed-
graft hybrid. This and one other instance else-
A STRIPLING FROM THE
TROPICS
In the foreground is seen the South
American bean whose stalk suggests the
one that Jack grew, according to the
nursery legend. T'o appreciate the size
of this tropical bean, it should be
explained that the corn in the expert-
mental bed beside it is more than
eighteen feet in height.
PEAS AND BEANS _158
where described are the only two similar ones
that ever came under my observation, and they
never, so far as I know, have been duplicated |
before or since. .
But the fact that the lima bean, the conspicu-
ous traits of which were mostly submerged and
subordinated in the mature hybrid, should have
made its influence strongly felt in the seedling
at the beginning of its growth is peculiarly in- ©
teresting.
One recalls the similar case of the raspberry
plant hybridized with pollen from the straw-
berry. In that case, the young hybrids at first
bore close resemblance to the strawberry plant,
yet subsequently shot up into the air and took
on the aspects of the raspberry vine. In
both cases, then, the influence of the seed
plant was at first submerged but ultimately
preponderant.
It has been pointed out that as a rule it
appears to make no difference in the ultimate
character of the hybrids as to which of its
parents is the staminate and which the pistil-
late one. In any event, the analogy between
the. hybrid beans and the hybrid strawberry-
raspberry, each following first the staminate
and then the pistillate parent, is not without
interest.
154 LUTHER BURBANK
OPPpoRTUNITIES FOR FuRTHER EXPERIMENT
After an interval of many years, during which
I did not experiment further with the bean, I
have somewhat recently found time to turn atten-
tion again to this very interesting plant, and have
developed a large number of new varieties of
unusual qualities.
‘The recent experiments have had to do with
the bush bean, and I have paid attention to a
large number of attributes, including form of the
plant, color of bean, and the quality and flavor.
The new experiments have involved the crossing
of many varieties and have brought to light many
interesting developments, although none perhaps
more striking than those just outlined.
It has been found that it is feasible to segre-
gate and recombine the traits of different varie-
ties of beans in almost any desired combination.
Thus, for example, it is perfectly feasible to put
the pod of one bean on the vine of another, quite
as Mendel did with his peas. Observation will
show what qualities or characteristics are pre-
potent or dominant even without directive effort
on the part of the plant experimenter.
It will be observed that in the second, third,
and fourth generation plants will appear that
show the pods and beans of one of the original
PEAS AND BEANS 155
parents combined with the leaves and vine of the
other, in all possible combinations. |
As I have operated with about sixty varieties
of beans in the course of these experiments, it
will readily be surmised that the number of new
combinations that have been presented is almost
infinite. Among the hybrid stock can be found
beans of almost every color and combination of |
colors, black, brown, blue, slate, yellow, green,
and white; mottled, striped, and otherwise vari-
ously marked and shaded. Moreover, if beans of
one color are selected and planted, as a rule all
the other colors appear in the progeny.
One finds the offspring bearing beans that are
speckled, spotted, striped, and shaded in every
conceivable way.
Yet beans that show this diversity of color may
be quite uniform as to size of the beans and time
of ripening, as well as in regard to the size and
general appearance of the plants on which they
grow. ?
In other words, a certain number of characters
may have become fixed while other characters are
still variable. And here the obvious explanation
is supplied, at least provisionally, by the supposi-
tion that the plants in question are unmixed as to
their Mendelian factors for size and character of
vine, but retain mixed factors for color of seed.
156 LUTHER BURBANK
No one as yet, however, has worked out in
detail the combinations of hereditary factors for
the bean as Mendel worked it out in the case of
the pea. Such an investigation would constitute
one of the most interesting experiments in plant
breeding that anyone who has time for it could
undertake. It is true that the hybridizing of the
plant of this genus is rather difficult, inasmuch as
the flowers must be opened and the stamens
removed with a pair of small forceps to avoid
self-fertilization.
But, on the other hand, once cross-fertiliza-
tion has’ been effected there are obvious advan-
tages in later generations in working with a
plant that is normally self-fertilized, the pollen
of which is inaccessible to insects.
All in all, I think the bean offers as many
inducements for improvement as any other plant
under cultivation.
Although much has been and may
be accomplished with peas and
beans by mere selection, these
plants offer exceptional opportuni-
ties also for improvement through
hybridization.
THE TOMATO—AND AN INTER
ESTING EXPERIMENT
A PLant WuicH Bore Potators BELOw
AND TOMATOES ABOVE
preserving tomato and had learned its
origin was curious to know just how I
came to make the hybridizing experiment that
resulted in its production.
I found it difficult to answer the inquiry to his
entire satisfaction. One does not recall all the
details as to methods, let alone motives, after an
interval of twenty-five years. But so far as can
be recalled, I had no very definite object in
combining the common tree tomato (tomato de
laye) and the currant tomato except the one of
general interest in the processes of nature, and
a sort of all-inclusive desire to see what would
happen when plants of such very diverse char-
acter were united. |
My visitor felt that I must have had some
definite idea in mind—some ideal tomato at the
157
A VISITING scientist who had seen my little
158 LUTHER BURBANK
production of which I was aiming, and he seemed
to feel distinctly dissatisfied when assured that in
this particular case a result had been achieved
that had not been forecast. The plant developer
had been like a chemist putting together newly
discovered elements. He knew that he would
probably get something interesting, but just
what that something was to be could not be
predetermined,
Two Types OF INVENTIONS
This incident is recalled by way of illustrating
another phase of the plant developer’s art than
that illustrated by the development of the can-
ning pea as detailed in the preceding chapter.
In that case, it will be recalled, the plant de-
veloper was in the position of an inventor called
upon to meet a precise set of specifications. He
knew from the outset what was to be aimed at
and, having acquired a certain craftsmanship, he
knew how to set about securing it.
A large number of inventions in the mechani-
cal world have such an origin as this.
When Edison started out to find a filament
that would show just the right resistance to the
electric current, and yet would not be consumed
with its own heat, he knew just what he was
seeking, and his problem of the development
THE TOMATO © 159
of an incandescent light bulb was comparable,
in a general way, to the problem of producing
a canning pea of just the right size and
quality.
But, on the other hand, a long list might be
cited of inventions and discoveries of vast impor-
tance that were matters of accident. Perkins’s
— discovery of the aniline dye; Nobel’s discovery of |
nitroglycerine; Réntgen’s discovery of the X-
ray; Becquerel’s discovery of radio activity—
these are instances where a man found something
for which he was not specifically looking. Of
course he had to be in line of discovery. It was
essential that he should be handling the right
materials, and working in a laboratory having
the right accessories, or the discovery could not
have been made. Nevertheless, in each case, the
discoverer found something for which he was not
seeking; his experiments had results that he
could not have predetermined.
And, here again, the analogy with that other
type of experimentation through which, for ex-
ample, the preserving tomato was developed will
be obvious.
_ LookINe For SURPRISES
The point to be emphasized is that the plant
developer is an inventor who works sometimes
according to one method and sometimes accord-
FRUITS OF A TOMATO
HYBRID
These interesting tomatoes were the
products of an early experiment in
_ which the so-called currant tomato was
crossed with the upright-growing tree
tomato. The result is here shown in the
numerous forms, sizes, and colors. The
“Burbank Preserving” tomato intro-
duced by the Burpee seed house about
1895 is a selection from this lot.
dl
THE TOMATO 161
ing to another. He is dealing always with com-
plex and intricate matters. Sometimes he has
studied them so well that he knows what to ex-
pect of them in certain combinations. In other
cases he is feeling his way, and has no very clear
notion of what to expect.
It might be said that he is looking for sur-
prises rather than for anything definite; and in
that event he is pretty sure to find what he is
looking for.
_ Such at least was my experience in the early
experiments with the tomato that led ultimately
_ to the production of the particular hybrid at the
moment under discussion. These experiments
had their origin at the very beginning of the
period of my investigations in the field of plant
development, a good while before I came to
California.
But in those days, notwithstanding one or two
successes, I was only laying the foundation
for my future work—learning how to handle
the tools of my trade. So although there
may have been interesting discoveries within
reach, I did not always know how to grasp
them.
I had not learned, for example, the all-impor-
tant lesson that the second generation hybrid,
rather than that of the first generation, is the one
6—Vol. 5 Bur.
~ 162 LUTHER BURBANK
that must be looked to, in a large number of
cases, for important development.
THE Story OF A F'RUITLIKE TOMATO
But when I came to California and found
opportunity for expanding the work, from time
to time I took up the old New England experi-
ments where they had been left.
In some cases I had brought seeds with me,
and was able to complete under the new condi-
tions experiments that had been begun in New
England. In other cases it was necessary to
start anew, but with experience as a guide that
constituted an asset that often proved a won-
derful timesaver. .
In the ease of the tomato, experimentation
was reopened on a comprehensive scale about the
year 1887. It was at this time that I hybridized
the tree tomato aid the currant tomato and pro-
duced the interesting new form about which we
have just spoken. The common tomato needs no
description, but the currant tomato is much less
familiarly known. It is a plant with long,
slender, trailing vines and slender leaves and it
bears racemes of small currantlike fruit. It oe-
curred to me that it would be highly interesting
to hybridize this trailing plant with an upright,
compact variety of the common tomato.
THE TOMATO 163
The cross was made reciprocally, pollen from
each plant being used to fertilize the stigma of —
the other.
The fertilization was effected without difficulty
and an abundant supply of seed was produced.
The hybrids that grew in the next generation
were many of them pretty clearly intermediate
in form and appearance between the parents.
But some of them were almost ludicrous in
appearance. They took on twisted and con-
torted forms, and in particular their leaves were
curled and twisted into fantastic shapes.
As to fruit, some of the plants produced long
clusters with tomatoes much larger than cher-
ries; others furnished small fruit like that of one
of the parents. And in some cases a plant that
had retained the short stocky tree form of the
tree tomato bore clusters of small tomatoes in
bunches similar to those of the other parent.
The foliage varied astonishingly between the
two types. In some there was an exact compro-
mise that was very curious. The dark, blistered
leaves of the tree tomato, combined with the long,
slender leaves of the currant tomato, produced a
most interesting effect. Other specimens showed
every possible gradation between the parent
forms. Here, then, was a case in which there
was no conspicuous dominance of one parent or-
164 LUTHER BURBANK
the other as regards any individual character that
could be segregated and classified.
Neither as to size and form of plant stalk, nor
as to leaf, nor as to the fruit itself, was there clear
prepotency or dominance of one parent over the
other. :
If there was an exception to this it was “per-
haps that the fruit tended to be borne in clusters,
as in the case of the currant tomato, rather than
singly or in small groups as with the tree tomato
Attention is called to these diversities because
it is well to emphasize anew that the phenomena
of the clear segregation of “unit” characters, with
the exhibition of dominance and recessiveness—
which the pea with which Mendel experimented
manifests so beautifully, and which we have seen
manifested in the characteristics of numerous
other plants—is not a universal phenomenon
that the plant experimenter may confidently ex-
pect always to discover and use as an easy and
simple guide along the path of plant develop-
ment. Different species of plants, different
varieties, even different individuals show diver-
sity as to the extent to which the so-called unit
characters are segregated and mutually com-
bined or antagonized, and as the reader who has
followed the story of various plant developments
already outlined is clearly aware.
THE TOMATO 165
We shall have occasion to revert to this subject
more than once, and to point out various possible —
interpretations of the phenomena, various under-
lying harmonies that do not appear on the sur-
face. But for the moment we are concerned
with the story of the new tomato, and may be
content to put forward the facts regarding it
without great insistence on their theoretical
interpretation.
Suffice it that the progeny of the treelike
tomato and the trailing one were a varied com-
pany, giving the plant developer almost endless
opportunities for selection.
I chose, naturally, from among them those
that bore the handsomest and largest fruit, and
in planting these was enabled, in the course of
several generations, to secure a very handsome
plant with attractive fruit of new type which
came true from seed. It required about six years
to produce and make sure of the new variety,
which was announced in my first catalogue of
new plants, issued in 1893. The description
there given of the new fruit was as follows:
AN INTERESTING HypBrip
“This distinct novelty and ornamental fruiting
plant grows about twelve inches high by fifteen
inches across.
POTATOES WITH A STRANGE
HISTORY
These are potatoes grown on a vine
on whose stalk a tomato top had been
ingrafted. The potato leaves were
unable, apparently, to supply just the
right kind of material in abundance for
the making of the best varieties of
potatoes, but they made a creditable
effort nevertheless. Considering that
no tomato vine had. ever grown a potato
at all before, the result might be said
to be notable. These were produced
about 1880.
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THE TOMATO 167
“The curious plaited, twisted, and blistered,
but handsome leaves, sturdy, compact growth,
and odd clusters of fruit will make it a favorite
ornamental plant.”
Another account supplemented this by de-
scribing the fruit as “a small, round, scarlet
tomato, borne in clusters, the individual fruits
measuring only three quarters of an inch in
diameter; of splendid scarlet coloring and un-
usually rich, sweet flavor.”
The comparatively rapid development of this
curious form of plant, so widely divergent from
the ordinary tomato, illustrates the possibilities
and suggests the compelling interest of such ex-
periments in hybridizing and selecting even our
commonest garden plants.
The work is, of course, no different in principle
from that followed by the plant developer in the
orchard, whose work has been detailed in earlier
volumes. But there is this important practical
difference: In experimenting with such a plant
as the tomato, we get results quickly because the
plant grows and fruits in a single season. The
results of any given experiment may be known
within a few months of the time when the seed
is planted. This is quite different from the case
of the orchard and especially nut trees, which
require, as we have seen, long periods of patient
168 LUTHER BURBANK
waiting, few of them bearing, even under un-
usual methods of grafting, in less than two or
three years, and some of them, such as the pear
and fig, requiring a much longer period.
On the other hand, there is one regard in which
the orchardist has an advantage. It is not neces-
sary for him to fix his new varieties so that they
will come true from the seed, inasmuch as his
plants will propagate by division. But in deal-
ing with plants of annual growth, like the
tomato, it is obvious that a new variety can have
little value unless it will come true from the seed.
(The tomato is really a perennial that is grown
as an annual.) —
So the task is not completed when a new vari-
ety is produced; additional experiments must be
conducted to fia the variety. Even this may be
accomplished, however, by careful attention to
selection, in the course of a few years, as we have
just seen illustrated in the case of the hybrid
tomato. ,
NINETEEN-YEAR-OLD SEED
Among my later experiments with the tomato
were some that had exceptional interest because
of the material used. |
It chanced that when I left home in the East,
many years before, I brought with me seed of
several of the standard varieties of plants and of
THE TOMATO 169
some crossbreed varieties; and, as has been
pointed out, I was hybridizing tomatoes, pota-
toes, beans, and other plants even at that time. _
The lot of seed thus brought to California
included some seeds of the tomato. As was cus-
tomary in those days, this seed had simply been
pressed out of the fruit, and dried on a piece of
paper with the surrounding mucilage still cling-
ing to it. |
Nineteen years afterward I planted some of
these seeds, being interested to see whether they
retained their power of germination. Somewhat
to my surprise, almost every seed germinated.
But the majority of the seeds did nothing more
than form cotyledons, lacking the central bud
for further development. There were a few ex-
ceptional plants, however, among the large com-
pany—perhaps altogether two dozen—that con-
tinued their growth and in due course fruited.
The fruit of some of these plants grown from
nineteen-year-old seed was sent to an eastern
horticultural journal, whose editor commented
on the fact that seed kept for this long period
still produced fruit quite equal to anything that
had been developed in the intervening nineteen
years. |
In planting the nineteen-year-old seed, I re-
tained a certain quantity from the same lot for a
170 LUTHER BURBANK
further test: The following year it was planted
in the same careful manner. But although a few
of the seeds germinated and sent up cotyledons,
not one had the power of developing beyond
that stage.
All of these seeds in-the twentieth year seemed
to have lost the capacity to produce a central
bud from which the plant stem could develop.
Of course it may have been only an accident
that a few seeds were able to take on mature
growth after nineteen years, whereas not one
could do so after twenty years. But I am in-
clined to think that the seeds had reached just
about their limit of suspended vitality. The facet
that germination began, but that it did not ¢on-
tinue because of lack of a central bud, suggests
that degeneration of part of the substance of the
seed had taken place. Seemingly it was only the
most resistant seeds that were able to stand this
degenerative process, and retain unimpaired
vitality to the end of the nineteenth year. The
heredity of those that grew was preserved in-
tact: the seeds producing exactly such plants and
fruit as if they had been planted nineteen years
before.
THE VITALITY OF SEEDS
The interesting question arises as to whether
the degeneration of germinal matter was con-
THE TOMATO 171
fined entirely to the store of nutrient substance
in which the germinating nuclei of the future
plant are embedded, or whether it included any
portion of the germinating structure itself.
The fact that failure to continue growth—in
the case of the seeds that put forth cotyledons
and then died—-was due to a lack of the central
bud that usually puts forth between the cotyle- |
dons, suggests that the germinal substance itself
was impaired. Of course this germinal matter
is of tangible, even if very minute, size, and there
is no apparent reason why it might not be im-
paired as to a portion of its substance.
Conceivably, the substance of the complex
molecules making up the germinal protoplasm
may undergo a gradual process of decay or dis-
integration through the throwing out of some of
their atoms, somewhat as radium and its allied
substances are disintegrated. This of course is
a pure assumption, yet it is not altogether with-
out plausibility.
But whatever the precise manner in which the
degeneration of the germinal plasm is brought
about, the suggestion that one portion of its
structure may be affected more than another
raises a question as to whether, conceivably, such
a deterioration of the germ plasm within a seed,
in an exceptional instance where a seed is stored
TRANSPLANTING SELECTED
SEEDLINGS
Seedlings grown in the ideal soil are
being transplanted at a very tender age.
The process is very simple, being
effected with the aid of a knife blade, as
the picture clearly shows. There is no
particular rule about it, except to be
sure that you get about all the roots of
the tiny plant.
fox \s
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si oe SF eee oe
ef a2 us fi N
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5 Fal OR, ‘ ‘
ch x - “ %
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ms . oe
°
THE TOMATO 178
for a number of years before being placed under
conditions proper for its germination, might not
result in the production of a deformed or modi- |
fied plant. | |
Whatever differences of opinion may be held
among biologists as to the possible transmission
of modifications of the body plasm, all are’
agreed that modifications of the germ plasm be-
come a permanent heritage and are passed on
to the offspring. So it seems at least a pos-
sibility that we have presented, in the deteriora-
tion of the germ plasm within the seed, an ex-
planation of the appearance of mutants or sports
that may become the progenitors of new races.
Attempts to produce mutants by treating
the ovules of plants with chemicals, including
radium, have been made by several experimental
botanists, notably by Dr. D. T. MacDougal, of
the Desert Laboratory at Tucson, Arizona, and
by Prof. C. S. Gager. Prof. MacDougal’s
evening primroses, grown from seeds that were
treated with chemicals while in embryo, some-
times differ markedly from other plants of the
species.
Prof. T. H. Morgan has made similar experi-
ments with the eggs of a fly, treating them with
radium, and thus producing individuals strik-
ingly different from their parents.
174 LUTHER BURBANK
These experiments, then, although they mark
merely the beginning of a new line of research,
are interesting in their suggestiveness. And it
occurs to me that the case of the nineteen-year-
old tomato seeds may have a bearing on the
same subject.
It would be well worth while to conduct a
systematic line of experiments in which seed of
a fixed species is stored in large quantity, and
a certain proportion planted each year, careful
record being made of the characteristics of the
successive groups of plants, with an eye to any
modifications that may occur when the seed
approaches the limit of the term through which
it can maintain vitality under the conditions
given it. ;,
It is said that there are records of whaae
germinating after it had been preserved for cen-
turies in the tombs of Egypt, although there is
no proof of this; but most seeds have far more
restricted capacities for maintaining vitality.
My experiment suggests about twenty years as
the limit for the tomato seed under fairly good
condition. So the seeds of some fixed type of
tomato might very well be among those selected -
for such an experiment as that just suggested.
My own observations in the matter are chiefly
confined to what has just been related to the
THE TOMATO 175
nineteen and twenty-year-old tomato seeds; and
must leave further investigation along this line
to younger experimenters.
GRAFTING ToMATO AND Potato
_ Doubtless among the most interesting experi-
ments (to the general public) with the tomato
have been those in which this plant was grafted
on the stalk of the potato; together with the com- —
plementary experiments in which the potato was
grafted on the stalk of the tomato.
The grafting of herbaceous plants such as
these presents no complications as a mechanical
procedure. The fact that the stem is succulent
throughout makes such grafting a less delicate
proeess than the grafting of twigs of trees, for
example, in which, as we know, it is necessary to
bring the cambium layers of the bark in accurate
contact. With herbaceous plants like the potato
and tomato, the stem may unite at any portion
where the cut surfaces come in contact. To
make a neat and thoroughly satisfactory graft,
however, it is of course desirable to select stems
of exactly the same size.
The splice graft, elsewhere described, is the
_ best one to use, and if the incisions are made with
care, so that the incised surfaces fit accurately
together, it is only necessary to tie a piece of
176 LUTHER BURBANK
cloth about the united stems for a few days until
union has taken place. It is not necessary to
use grafting wax, if protected from winds and
too hot sun.. The operation is preferalty. per-
formed in the greenhouse.
By this method, I grafted the tops of young
tomato plants on the main stalks of potato
plants, at a time when the stems were about one-
quarter of an inch in diameter. The reverse
operation, grafting amputated potato tops on
tomato roots, was performed at the same time.
Of course the tomato and potato belong to the
same family, and it seemed reasonable to suppose
that such grafting might be successful. But, on
the other hand, numerous attempts have been
made to hybridize the two plants by cross-
pollination, and these have always resulted in
failure. I have tried it many times, and have
never been able to fertilize one plant with pollen
of the other. We know that, as a general rule,
plants that cannot be cross-pollenized cannot be
mutually grafted. The same barriers usually
exist in one case as in the other.
The potato and tomato grafts, however,
proved very notable exceptions to this rule. In
both combinations the union between the foreign
stems took place quickly, and resulted in a stem
as strong as the ordinary stem of either plant.
THE TOMATO 177
Growth continued, and the plants: came to
maturity at about the expected season.
- But the results of the strange alliance were
interesting to the last degree.
They must be considered in detail as having
a bearing on one of the most interesting open
problems of plant development—the question of
sap hybridism.
PotTATOoEs GROWN ON Tomato VINES
The tomatoes that grew on the root stalks of
the potato developed much as other tomato vines
do, although in some cases it seemed that the
vines bore closer resemblance to potato vines
than is usual. But the fruit that appeared in
due season was a tomato differing in no very
obvious respect from other tomatoes of the same
variety. ‘They, however, were not of as good
quality.
Meantime the potato roots, which supplied
water and mineral salts to the tomato vine above
them, and which in turn must receive material
for the growing of their tubers from that vine,
showed quite unmistakably the influence of the
foreign system of leaves with which they were
associated.
- Instead of being smooth and symmetrical like
ordinary potatoes the tubers were small and ill-
178 LUTHER BURBANK
shaped, and some of them had rough and cor-
rugated sealelike surfaces, suggesting the skin
of a lizard rather than that of a potato. More-
over, they were bitter in flavor and utterly un-
like the ordinary potato in taste. They further
showed their departure from the traditions of
their kind by manifesting a tendency to sprout
even while the tomato top was still growing
vigorously.
Perhaps these results, as regards both the
relative normality of the tomatoes borne by the
grafted vine, and the abnormality of the pota-
toes grown by the roots, might have been ex-
pected. At least they seemed quite explicable.
It will be recalled that the conditions of plant
growth were detailed somewhat at length in the
first chapter of the present volume, and that it
was there pointed out that the plant roots absorb
from the soil about them mineral salts in solution
that are carried up to the leaves of the plant be-
fore they are transformed into organic matter
by combination with carbon drawn from the air.
It was noted that the organic compounds thus
manufactured in the leaves of the plant must be
sent back down the stem of the plant to be de-
posited, in case of a tuber-forming plant like the
potato, in connection with the roots in the
ground.
THE TOMATO 179
It follows, then, that the tomato plant, even
though its source of supply was the root system
of a potato, merely gained from these roots
part of the raw inorganic materials with which
its leaves were to manufacture the special
compounds that go to make up a tomato.
Inasmuch as the tomato leaves were them-
selves unmodified, there was no reason why.
their product, the tomato, should be greatly
modified.
“In receiving its supply of raw material from
a foreign root, the tomato top was in no dif-
ferent condition from the ordinary cions in @
fruit orchard, which, as we have seen, are habitu-
ally grafted on roots or branches of a foreign
species.
But the case of the potato tubers is obviously
quite different. Their substance is made up of
material that came originally, to be sure, in part
from material gathered by potato roots; but this
material had traveled up to the leaves of the
tomato plant and had there been transformed;
so when it returned to be deposited and form
tubers it was a tomato compound and not a
potato compound.
It was not absolutely different in material
from the material of the ordinary potato, be-
cause the tomato and potato are cousins.
180 LUTHER BURBANK
But the modification had been great enough
to transform the tuber, and make it a deformed
and perverted thing, more or less comparable,
doubtless, to the tubers of some ancestral race
from which both the tomato and potato have
developed.
The extraordinary Ta, perhaps, was that
’ the tomato should have manufactured starch in
such quantity as to have supplied material for
even these dwarf tubers, inasmuch as the normal
tomato plant produces no tubers of its own. But
seemingly the buds designed to produce tubers
on the potato roots made an incessant appeal that
the vine above could not resist, even though it:
was able to fulfill but imperfectly the specifica-
tions for a potato tuber.
AERIAL POTATOE
Meantime, what of the potato tops that were:
grafted on the stem of the tomato? _How did
these prosper?
Here, it is obvious, were complications of a
different order. The tomato vine obviously
could bear no tomatoes because it had no
tops. Meantime the potato vine was equally
handicapped as to the production of sub-
terranean tubers since it had not roots of its
own kind.
THE TOMATO © 181
‘But the tomato roots of course sent up their
supply of water and salts in solution, and the
potato leaves set to work as usual developing
material for the manufacture of tubers. When,
however, the effort was made to send this ma-
terial for tuber formation back to the roots, there
was an embargo put on such transportation be-
cause the tomato roots have no knowledge of the |
art of tuber making.
In this dilemma the potato crop, under spell of
the compelling instinct of tuber formation, made
the only compromise possible by growing aerial
tubers at the joints where the leaves appear from
buds springing from the point of union with the
leaves of the stem.
What would ordinarily have been leaf-bearing
branches were terminated with small potatoes,
which, because of exposure to the sunlight,
generally took on a greenish tint, those in full
sunlight sometimes being thoroughly green,
while those that were shaded by leaves were of a
lighter color.
The potato vine growing on a tomato stem
and bedecked with aerial potatoes, like some
strange form of exotic fruit, was certainly one
of the most curious forms of plants ever seen.
It is perhaps needless to add that the potato vine
produced no fruit that gave any suggestion of
“189 LUTHER BURBANK
the influence of the tomato. The tubers it grew
were potatoes and nothing else; their modifica-
tions in form and color were obviously due to the
lack of their natural protective soil covering.
But the fact that the vine, handicapped by
lack of roots of its own kind, should have been
able to transform leaf buds into tuber-growing
aerial rootlets furnishes an interesting lesson in
the metamorphosis of parts. How the great
poet Goethe, who first expounded the theory of
metamorphosis of parts, and clearly recognized
the fundamental unity of stem and leaf and
flower, would have enjoyed the viewing of a
spectacle like that!
QUESTIONS OF SAP HYBRIDISM
And for the modern plant developer, the
strange compound vines have no less interest,
for they suggest a number of questions that are
much easier to ask than to answer.
How, for example, was the leaf system of the
potato that grew the aerial tubers to know that
tubers were not being formed about its roots in
the ordinary way? It did know this, obviously,
else it would not have adopted the unprecedented
expedient of growing tubers in the air.
It is easy to speculate, and to suggest, for
example, that the potato plant producing an
THE TOMATO 188
excess of sugar and starch in the usual way,
must find some place to deposit it, and that as no
demand came from the roots, the only available
buds were made to do vicarious service. But the
explanation obviously lacks a good deal of com-
plete satisfactoriness. For the moment, we per-
haps must be content to recognize in this another
illustration of the fact of communication between |
the different parts of a plant, and of the
harmony of purpose through which the plant
as a whole is made to respond to the conditions
of thé environment in the iphess that best meets
its needs.
But we are forced to recognize, shou gh such
an illustration, a greater capacity for adapta-
tion, seemingly almost of a reasoned character,
than we are commonly wont to ascribe to the
plant.
The case of the tomato plant growing on the
potato roots, which so perverted the character of
the tubers that it supplied, has practical interest
for the plant breeder, and in particular for the
orchardist, because it demonstrates the effect of
a cion on the stalk on which it is grafted. Of
course the ordinary fruit tree does not develop a
system of tubers, and so it does not call for such
a supply of starch, for example, as that which
the tomato vine was induced to produce for the
184 LUTHER BURBANK
tomato. roots. But the root system of any tree
requires nourishment if it is to develop, and this
nourishment, as we have seen, must be supplied
by the leaves of the tree above it, even though
the roots themselves first collect part of the
materials. x
It follows that the root system of any tree,
while it is absolutely essential to the leaf system
above it, is also very largely dependent on that
system.
In other words, there is the closest recip-
rocal relation between root system and leaf
system.
This relationship, which many orchardists
overlook, has been long recognized and re-
peatedly referred to. But the case of the to-
mato on the potato root emphasizes the lesson
in such terms that no one can ignore it. With
this illustration before us, we can scarcely doubt
that the root system of any stock on which a for-
eign top is grafted (as is the custom in most
orchards) is modified in some measure by the
cions it bears. The foreign leaves cannot supply
precisely the same quality of nourishment to the
root that leaves of its own kind would have
supplied.
In the main, no doubt, the protoplasm of the
root assimilates the nourishment that comes to
THE TOMATO - 185
it, and makes it over into its own kind of proto-
plasm. But we know that the flesh of animals
varies in quality with the food given the animal,
and we cannot well doubt that the protoplasm
of the root of a plant must similarly be modi-
fied by the character of its food.
_ And this line of thought suggests the further
possibility that when more cions than one are
grafted on the same branch or on the same trunk,
there must be a certain intermingling of the sap
from the different leaf systems in the course of
the journey to the roots of the tree; and that it
might very conceivably happen that a sufficient
blending would take place so that the modified
sap might find its way to the fruit buds of a
given cion, and affect the character of the fruit
ina way not altogether unlike the effect of
hybridizing.
This would account for the case narrated at
length in an earlier chapter, in which a cion of
the purple-leaved plum grafted on the stem
of a green-leaved Kelsey plum tree appeared
to influence the fruit of a neighboring stem
so that the seedlings that grew from that
fruit bore purple leaves, and smaller crimson
fruit.
As before stated, such a striking instance of
evident “sap hybridism” is exceedingly rare; but
186 LUTHER BURBANK
can we be sure that influences of a less tangible
character are not constantly exerted by in-
grafted limbs?
May it not be possible, even, that the influence
of cions from many sources on one another, when
they are placed together in large numbers on a
single tree, as in the case of my colonies of plums
and cherries and apples, may be: very notable
indeed, even though of such character as not to
be demonstrable? Is it not at least possible that
the improved quality of the new and splendid
varieties that appear on the various cions of these
multiple trees is in some minor part to be
ascribed to the mutual influence of cions of many
different strains of past generations, one on
another?
If this thought be permitted, we must ree-
ognize in such fruit colonies as those in question
an influence exercised by the community for the
benefit of the individual that is comparable to
the intangible influences through which a com-
munity of human beings affects the moral char-
acter of its individual citizens.
All this carries us somewhat afield from the
case of our grafted tomato-potatoes, but only to
the extent of a natural application of principles
clearly suggested by the phenomena exhibited
by these extraordinary plants.
THE TOMATO 187
A GLANCE AHEAD
Let us repeat that the grafting of these two
plants is not a difficult procedure.
It is well worth the effort of any amateur to
_ repeat these experiments (so far as I know, this
has not been done until recently, and its signifi-
cance has never been fully appreciated), and to
observe for himself the curious phenomena that
will result.
Possibly the results of my own early experi-
ments might not be exactly duplicated. But
there is little doubt that interesting and en-
couraging developments would result.
RC) Ate by | "a
Maree ont ;
CY a. Sis wat
ir
EGE J ae ay
. cae wd. bere bone te!
, 3, eyes ih tas ;
SOME PLANTS USED FOR
FOOD AND FLAVOR
.-SOME SUCCESSFUL WorRK WITH THE
Lity FamILy
HAT there is such a thing as being too
popular, many plants have learned to their
-sorrow. For popularity, with the plant,
implies a kind of attractiveness that results in
the plant being eaten by some herbivorous ani-
mal. The animals can secure food in no other
way, so they are not to be blamed for their
marauding. But in the meantime the appeasing
of their appetites is destruction for the succulent
herbs.
The only resource of the plants is either to
develop extraordinary capacity to thrive under
adversity, as the familiar lawn grasses do; or to
develop weapons of defense.
These defensive measures may take the form
of a tough and indigestible fiber as in the case of
woody shrubs; the studding of the plant surface
with spines as with the blackberry; the produc-
189
190 LUTHER BURBANK
tion of a crop of stinging hairs as with the nettle;
or the secretion of oils or other chemicals that
have offensive odors, or bitter, acrid, or peppery
taste.
In the present chapter we are concerned
mostly with a conglomerate group of plants,
several of which belong to the lily family, that
have resorted to the last-named expedient in the
attempt to protect themselves against the unwel-
come attention of herbivorous beasts. The onion
and its allies, the mints, mustard, peppers, and
the others of this company are for the most part
lowly herbs or succulent bushes that have quali-
ties of flesh that make them attractive. In self-
defense they have developed added qualities,
chiefly through the manufacture of essential oils,
or odors or flavors that are the opposite of
appealing. |
But as in a good many other instances, these
plants by their very zeal to some extent defeat
their own purposes. The unique quality of the
flavors they develop, even though at first repel-
lent to the palate, serve as a stimulus to the re-
ceptive mind of man, and urge him to develop a
taste for the very things which at first seemed
repellent.
So it has happened that plants that seem by
the very nature of their product to be denied
FOOD AND FLAVOR 191
presence on the table have come to be regarded
everywhere as admirable accessories to the diet-
ary, supplying flavors that pique the appetite
and facilitate digestion. ‘These stimulators of
jaded appetites are perhaps of somewhat doubt-
- ful benefit, if we are able to accept the findings
of the physiologist, but they have a recognized
place in the modern kitchen, and various and
sundry of them are among the most important of
garden vegetables.
At the head of the list, doubtless, if we con-
sider universality of vogue, are the members of
the onion family, including onions proper of
many varieties, and such allied species as the
garlic, the leek, and the chive.
WoRK WITH THE CHIVE
I have worked a good deal with most of these,
but have found perhaps greatest interest in de-
veloping the one of them that is least generally
known —the chive (Allium schwenoprasum).
The particular work of recent years with this
plant has had to do with a variety which bore
a flower that was originally dull crimson
in color, and which, notwithstanding its dis-
agreeable odor, appeared to combine the quali-
ties of a border plant with those of a food
plant.
192 LUTHER BURBANK
Seed of the chive was secured in Europe and
seedlings raised for eight or more years, carefully
selecting in each generation the ones that most
appealed. There was a considerable tendency
to vary within rather narrow limits. some plants
being deeper in color than others, but the diver-
gence was not at first very marked.
In the third year, however, there appeared
a variation having a blossom of bright red
color instead of the usual rather deep dull
crimson.
As the chive can che multiplied indefinitely by
division, this single plant might have become the
progenitor of a race of red-flowering chives. But
I wished to see what the hereditary tendency
would be, and so raised about ten thousand seed-
lings from the red-flowering’ stock. Nearly all
of these seedlings reverted to a pink color.
There had been a faint tinge of rosy pink in the
original flower, obscured by the crimson, but the
new seedlings bore larger blossoms of a pleasing
pink color, and constitute a new and highly
attractive variety.
While thus developing a pleasing flower and
thereby adding to the attractiveness of the chive
as a border plant, I paid attention also to the
bulb and stalk of the plant itself as well as to
the flavor. :
FOOD AND FLAVOR 193
In the course of ten or twelve generations a
bulb was so developed that the average size is __
more than twenty times that of the bulbs of the
stock of the well-known ordinary chive.
Thus the new race of chives not only supplies
a pink flower which has a very handsome effect
when massed in contrast with the characterless
flowers of its ancestor, but it is also relatively
gigantic in bulb as compared with them. Thus
its value as an ornamental plant and its utility as
a food plant were enhanced simultaneously, and
somewhat in the same proportion.
These results have been attained by selective
breeding, without hybridizing, in the course of a
comparatively small number of generations.
Development has progressed along yet an-
other line. The one chief objectionable feature
of plants of this tribe, as everyone knows, is their
odor. But it is well known also that different
members of the onion tribe differ greatly in this
regard. In recent years the large sweet Italian
and Bermuda onions, which are very mild and
relatively odorless, have been introduced, and
the possibility of removing from the members of
the tribe their objectionable odor has come to be
more generally recognized. It appears that the
Italian varieties have been rendered odorless by
selection from ordinary onions. Some of the
7—Vol. 5 Bur.
A SOUTH AMERICAN
ALLIUM
Here is a plant with a nightcap; or, if
you prefer, a dunce cap. The pro-
tective covering of the flower bud has
burst open, but has not been discarded;
hence the curious effect. This is not, as
might be supposed, a mere accidental
individual peculiarity, but is character-
istic of the species. It might be difficult
to guess, however, what protective
function the nightcap subserves.
FOOD AND FLAVOR 195
improved Italian varieties are so mild in taste
that they can be eaten like an apple.
In experimenting with the chive I have natu-
rally not overlooked this quality, and some of
these improved varieties show a marked advance
upon its ancestors in regard to quality as in -
regard to size of bulb and beauty of flower.
IMPROVING OTHER ALLIUMS
My work with the other members of the family
has been fairly extensive, inasmuch as I have
experimented first and last with about fifty
species of wild and cultivated Alliums from Eu-
rope, Asia, and America, especially Alaska, and
with various forms from Chile and from China.
The onion, a member of this lily family, is an
interesting plant with which to work, and from
the fact that it shows a good measure of respon-
siveness. The wild onions are exceedingly vari-
able and the cultivated species no less so.
Indeed, this might be taken almost for granted
considering the long period during which the
onion has been under cultivation and the large
number of varieties that are in existence.
In addition to the ordinary species with its
well-known qualities, there are numerous hand-
some flowering varieties of Alliums. And in the
Sierras there is also a variety growing along the
196 LUTHER BURBANK
mountain streams which has a delicious, sweet
flavor much superior to the cultivated onion. I
have cultivated also a species from China which
is peculiarly sweet-flavored.
Some of the Chilean and Canadian leeks that I
have had under cultivation differ widely in form
from their northern relatives. Some of the
Chilean wild garlics have been classified as leeks
by the botanists and gardeners in this vicinity;
whereas the same observers classify certain of
the true leeks as garlics; which suggests the
divergence of form of some of these South Amer-
ican species.
I am now cultivating a wild garlic from the
mountains of Chile which is a wholly distinct
species from the common cultivated garlic, hav-
ing much larger bulbs and a taller stalk similar
to that of the leek.
My large collection of flowering Alliums from
California and other countries has, of course,
been made with the expectation of crossing these
plants among themselves or with commoner
varieties. There are interesting possibilities of
development all along the line.
The Spanish onion called the Prizetaker, be-
cause of the extraordinary size of the bulb, some-
times attains a weight of five or six pounds. That
new developments, perhaps of unexpected char-
FOOD AND FLAVOR 197
acter, will result when the varied races from Eu-
rope, Asia, China, and Chile are blended with
American stock is quite certain.
The onion is not very easy to hybridize because
of its small flowers. But it is only necessary to
use reasonable care to effect hybridization, and
the results are likely to repay the effort.
Indeed, whether by hybridizing or by mere
selection, the Alliums are susceptible of great
improvement along almost any line one may
choose. The odor, for example, may very readily
be intensified or decreased, and the size and
flavor modified. On the whole I regard this as
one of the most interesting vegetables with which
to work. But there are many other plants prized
for their flavor that also merit attention.
THE PARSLEY FAMILY
Prominent among these are the members of
the parsley. family.
The common parsley and its close relative ‘be
caraway vary a good deal in flavor in individual
plants grown from the same lot of seed. Only
persons with a developed or specialized sense of
taste are likely to notice this, however.
To the person who tastes them carefully, it
will be obvious that some specimens are much
sweeter and better flavored than others.
198 LUTHER BURBANK
But as the general public is not very discrimi-
nating, it is perhaps doubtful whether it would
be profitable to develop these into fixed varie-
ties. The market for these plants is of course
restricted at best.
A more tangible property, and one that is
likely to appeal to the user of the plant, is the
shape and quality of the leaves. I have worked
on the curled parsley to some extent and have
found that by careful selection it can be im-
proved greatly in a short time. The different
tendencies of the leaves can be fixed quite readily
in three or four generations.
I had also developed a golden-leaved parsley,
something like the golden-leaved celery. This
was a plant of great promise and I expected to
introduce it. But to my regret, it was destroyed
by millipeds just before it was ready to produce
seed, |
I have never seen another specimen, but of
course similar mutants might appear at any
time, for what has happened once to a plant
may happen again.
Another genus of the parsley family, Ligusti-
cum of the botanist and commonly known as
lovage, is cultivated to some extent in our gar-
dens for its aromatic seeds and roots. There are
several California species in the northern and
FOOD AND FLAVOR 199
central parts of the State. The roots are much
prized by the Chinese.
I have worked with these and other allied
species extensively for a number of years. The
native species or varieties of this family are hard
to differentiate, especially as they vary widely in
different localities. All have seeds or roots with
a characteristic pungent odor, but the quality of ©
the odor varies throughout the widest range,
from the most fragrant and attractive to the
most disagreeable.
These wild species offer opportunities for
development through cultivation and selective
breeding. My own work in this regard has
scarcely passed the experimental stage, however,
even though it has involved a large number of
species and varieties. There is opportunity for
interesting and valuable work in the develop-
ment of the possibilities of these bearers of
flavors that appeal to the palate.
MINTs AND THEIR ALLIES
I think I have grown all the mints and pot
herbs that have been under cultivation, and have
found them without exception variable in quality
when grown from the seed.
Indeed, to the persons who taste them with
care, it will appear that variation is the universal
200 LUTHER BURBANK
rule. Each individual plant when grown from
seed has a slight difference in fragrance, and in
the amount of essential oil that it contains; this
cil being, of course, the source of the fragrance.
It is not difficult by selection alone to obtain
varieties that are of exceptionally fine fragrance
and that produce a relatively large percentage
of the essential oil for which the plants are
usually grown.
When a new variety has been obtained, it is
not necessary to fix it so that it will breed exactly
true from the seed; for the most of these plants
can be increased by division.
The mints hybridize naturally where various
species grow in the same vicinity, as we have
pointed out in another connection.
In this way natural hybrids are sometimes
produced that are so vigorous as to replace the
original parent plants in the state of nature,
driving them out of existence on their own
ground. Among hybrid mints, whether natural
or produced by hand pollination, there will be
seedlings that grow with exceptional rapidity,
and that present peculiar shapes and much vari-
ation as to roughness and smoothness of leaves
and form of the spikes-and blossoms. In work-
ing with all these plants, I found that quality
was the one thing lacking. In any lot of seed-
FOOD AND FLAVOR 201
lings grown from the potherbs or plants some
individuals have odors that are positively dis-
gusting, and those of some add nothing to the
value of the plants, but detract when mixed with
the better ones.
All this is quite what might be expected when
we reflect that the mints are a rather numerous
family—that fact by itself proving their tend- ©
ency to variation.
Among the mints worked on recently are
species from South America that resemble the
peppermint yet are in some respects quite dis-
tinct. An unnamed species with a tendency to
cling to the ground more closely than other
mints and growing so rapidly as soon to cover
a large surface gives considerable promise.
This species is said to be very hardy, and was
sent by my collector from the mountains of
southern Chile; it has somewhat the fragrance
of the native peppermint. The yerba buena
(Micromeria Douglassi) is a common little trail-
ing plant in the redwood forests, sometimes
growing also among shrubs and along the edge
of fields. It has sweet-scented, round leaves,
and small, pale, insignificant, purplish flowers.
This plant is fairly constant in any given
locality, but specimens from different regions
vary a good deal, some being rather compact
A NEW ALLIUM
This is another of the species of
alliiums with which we have experi-
mented extensively. The relationship
with the onion is shown in the form of
leaf and particularly in the flower head.
Some of these alliwms have really hand-
some flowers; and an ornamental onion
is certainly an interesting anomaly.
iH
Sey,
rons
FOOD AND FLAVOR 203
growers while others produce long, runnerlike
branches. A species of this plant of exactly the
same flavor, but growing as a shrub, with bril-
liant fuchsialike flowers, has been sent me from
the high mountains of Chile. These evidently
sprang from one original ancestor, but in our
California varieties it is an insignificant trailing
plant, and its relative of the Southern Hemis-
phere is a tall shrubby plant with brilliantly col-
ored flowers. The Chilean de is also there
called yerba buena.
I have attempted to cross this plant with the
species from Chile, hoping thus to stimulate
variation and perhaps to produce a plant of
larger size, and through selection a variety of
permanent value. But the flowers of the plant
are quite small, making the process of cross-
pollenization a rather delicate one, and my
experiment has hitherto not proved successful.
This, however, is doubtless due to operating on
too small a scale. I have no doubt that more
persistent efforts will result in hybridizing these
species, notwithstanding they came from differ-
ent hemispheres.
Other mints with which some unusual re- '
sults have been accomplished are the sweet
marjoram (Origanuwm) and various species of
thyme.
204 LUTHER BURBANK
Of the former I have raised many thousands
of plants from seed, and have secured among
these half a dozen in which the flavor and aroma
are exceptionally pure and strong. In one of
these individuals the flavor is so much more spicy
than is usual that it may be said to constitute a
new type of flavor. The experiments in improv-
ing the plant are still under way and the
response made by the plant itself is prompt,
giving assurance of the production of improved
varieties. And scores of other plants of similar
nature have given like results, but need not be
specifically mentioned here.
The thyme also has been grown largely from
the seed, and have noted with this as with other
members of the family a very marked tendency
to variation. The most interesting variety that
I have developed has been produced by selection
from a seedling the leaves of which showed a
beautiful white center with very uniform edges
of a dark green, instead of the usual yellow and
green markings.
This plant, in addition to its beautiful leaf,
was a more compact grower than the old varie-
gated thyme. By selecting through successive
generations the novel leaf was accentuated and
fixed until it would come almost uniformly true
from the seed. This new ornamental variety
FOOD AND FLAVOR 205
was offered to a well-known dealer, but he
responded that the demand for thyme was so
small as not to justify its purchase. So the new
plant was allowed to drop out of cultivation.
Tue Mustarp FAMILY
The members of this family, quite unrelated
botanically to the ones we have just considered, |
illustrate the tendencies of different races of
plants to adopt similar expedients in furthering
their ends.
Being succulent herbs, like the parsleys and
mints, the mustards have devised a similar pro-
tective measure, namely the development of
essential oils that have a pungent and biting
taste. But here as with the others man has cul-
tivated a taste for what seemed a prohibitive
quality, and the mustards, including not only the
plants that give their name to the family, but
such allies as the peppergrass, the cresses,
and the horse-radish, have long held a secure
place in the culinary department of every
household.
My most extensive experiments in the culti-
vation of the mustard were carried out some
thirty-five years ago, working quite largely with
the Japanese and Chinese mustards, in combina-
tion with the common European mustard.
206 LUTHER BURBANK
These Japanese and Chinese mustards are
quite distinct from our species. One kind very
extensively used in China, and introduced by
the Chinese in California, has the appearance of
a large compact bunch of celery. The leaves are
perhaps two inches in width or even more, grow-
ing so compactly that the plant is even more
solid than an ordinary cabbage head, each plant
weighing from two to five pounds. The leaf-
stalks are blanched like celery. They have a
spicy taste suggestive of mustard that is very
palatable and refreshing. The plants are cooked
like other garden vegetables.
Another Chinese variety has greener leaves
and a looser habit of growth, the plant being
also considerably larger. This also is a pleas-
ant, spicy vegetable when cooked.
All the Chinese mustards run to seed quickly
at the approach of warm weather, so the seed is
usually sown quite early in the winter. The
young plants are stimulated to rapid growth by
good cultivation and fertilization, and fine large
plants are ready for the market in the early
spring. The plants are usually grown on raised
beds and are planted about a foot apart each
way. These are really remarkable vegetables
that should be much more generally cultivated
in the United States.
FOOD AND FLAVOR 207
In the Northern States, unless planted very
early in cold frames, they run to seed without
forming the large, succulent head that gives
them value.
_ Both the black and white mustard are com-
mon plants in California, the black mustard in
particular being prized for culinary purposes
when young and tender early in the winter and_
spring. The white mustard grows in enormous
quantities in the fields, especially in the region
about Monterey Bay, where the seed is collected
by the ton, to be ground into commercial mus-
tard. The white mustard in particular may
become a pest, as it is exceedingly difficult to
eradicate it, the seeds sometimes remaining in
the ground several years, part of them germi-
nating each season.
About the only way to eradicate it com-
pletely from the grain and other crops, is to
pull it just as it comes into bloom in successive
seasons.
My systematic work of selective breeding of
the mustards was carried out while making simi-
lar experiments with other members of the
family, including the turnips, cabbages, and
radishes. Some superior varieties were devel-
oped by selection, and the seed was sent east and
to various parts of the world. But the demand
208 LUTHER BURBANK
was small and the work was presently discon-
tmued, although several of these and similar
varieties developed are still catalogued by some
American and European seedsmen.
Other crucifers that the gardener thinks of
collectively, though. they represent various
genera, are the peppergrass and the various
cresses, including the nasturtium.
The common peppergrass is as variable as the
lettuce. There are large numbers of plants
horticulturally called cresses, with a consider-
able range of variation.
One of the most interesting forms with which
I have worked is a Chilean cress (Nasturtiwm
Chilense), which is as tender as the common
water cress during the rainy season, and which
has an astonishing ability to resist drought. This
Chilean variety will withstand our summer, even
if exposed to the blazing sun, and after a period
of dormancy will revive and grow freely as soon
as the fall and winter rains come.
Experiments with it have been confined to
selection for the development of varieties show-
ing the best qualities of the plant.
With the peppergrass I have worked some-
what more extensively. Some specimens of this
plant have very finely dissected leaves, having
worked to develop this variety which produces
-
FOOD AND FLAVOR 209
leaves very similar to those of the improved
varieties of parsley.
The plant is rather obstinate; nevertheless
several varieties having many of the desired
characteristics have been successfully developed
and fixed. | |
As the peppergrass is an annual it is of course
necessary to fix the new qualities so that they
will be reproduced in the seedlings. It is this
rather than the mere production of the variety
that offers difficulties.
The familiar horse-radish offers a notable con-
trast to the peppergrass and to most other mem-
bers of the family in the matter of seed. For
whereas the mustard, radish, turnip, cresses, and
the rest produce seed in the greatest possible
abundance, the horse-radish produces no seeds
at all.
The horse-radish does, indeed, bloom with the
greatest profusion. But the blossoms prove
sterile. The plant has entirely and probably
forever lost the power of producing seed.
Elsewhere I have referred to the fact of my
having created a small commotion among
amateur gardeners by the joking offer of one
thousand dollars an ounce for horse-radish seed.
Of course I knew that no horse-radish seeds
were to be had, yet I would gladly have given
A BASKET OF BURBANK
PEPPERS
Like most other products of the
garden, the pepper has come wnder our
careful attention, The large and hand-
some variety here shown has been
developed in the course of a few
generations of selective breeding, with-
out crossing. Similar results will
attend the efforts of anyone who will
go about the work of improving the
pepper with enthusiasm and zeal, using
ordinary garden varieties,
FOOD AND FLAVOR 211
then, and I would gladly now pay, at the rate
of $1,000 an ounce for horse-radish seed. But
there is not the remotest probability that anyone
will ever legitimately claim the prize. If the
seed should ever be found, it will probably be
dark-colored, and about the size of a common
black mustard seed.
I have received nearly or quite a thousand
letters informing me that the parties writing
could supply me with all the horse-radish seed I
could wish, inasmuch as their plants were bloom-
ing abundantly, and I subsequently received
large quantities of dried horse-radish buds, as
well as great quantities of the seeds of weeds of
various sorts, and have even received what were
alleged to be horse-radish seeds from market
gardeners. But the plants that grew from these
seeds bore no resemblance to the horse-radish.
The interesting features of this loss of the
power of seed production by plants that have for
long periods been propagated by the root or
from cuttings or tubers—including plants of
such diverse races as the banana, the pineapple,
the sugar cane, and the potato, and nearly all
plants generally cultivated in greenhouses, along
with the horse-radish—have elsewhere been
referred to. I may add that the loss of power
to produce seeds in the case of the potato is not
212 LUTHER BURBANK
of necessity complementary to the capacity to
produce tubers. For at least once in my experi-
ence a potato plant that by rare exception: pro-
duced seed developed at the same time some
of the largest tubers.that I have ever seen.
Nevertheless, there is an association between
seed production and development of the root
system, as we have seen illustrated. And it is
not unlikely that development of the root of the
horse-radish may have had an influence on its
seed-bearing capacity. It may be recalled that
the carrot and parsnip which produce roots
somewhat suggestive of that of the horse-radish
in shape and relative size, are biennials, and do
not take on the functions of root and of seed
development in the same season.
The roots are formed in the first year partly
at least to supply nourishment for the develop-
ment of the stem and flowers and seeds in the
ensuing season.
Whatever the relation between the root of the
horse-radish and its lack of fertility, the fact
remains that the plant is propagated solely by
division, and that hence there is no opportunity
for the development of new varieties or the
improvement of old ones. Each horse-radish
root is in effect a part of an original plant now
endlessly divided, and the variation in different
FOOD AND FLAVOR 213
roots depends upon conditions of cultivation or
nourishment, not upon inherent differences
beween the different plants.
It may chance some day that an exceptional
horse-radish plant will produce seed, just as an
exceptional potato plant does from time to time.
In that case there will doubtless be opportu-
nity to improve the horse-radish somewhat as I
was able to improve the potato or sugar cane by
growing plants from the seed.
But until such an exceptional seed bearer is
found, we must accept the horse-radish as it is,
and admit our powerlessness to change it
markedly.
THE PEPPERS
The versatile family of Solanums, several
members of which have already claimed our
attention, supplies an important group of plants
that are prominent among the producers of
pungent and aromatic flavors.
These relatives of the sunberry, tomato,
potato, and egg plant are the peppers, of which
there are large numbers of cultivated varieties
in different countries. :
The different peppers vary from the size of
a barleycorn to that of a very large apple and
even in some cases approaching the dimensions
of a small squash, and in color from black through
BURBANK PEPPERS
There is good opportunity for the
development of new varieties of
peppers through the blending of strains
of various races, as several are available.
Peppers grow far to the north, but
they were originally of semitropical
habitat. This handsome specimen was
produced by selection alone from an
ordinary garden variety. Sometimes
these are nine inches long and five
across.
FOOD AND FLAVOR 215
scarlet, crimson, orange, and yellow to pure
white. In form, some are nearly flat, others
oval, yet others round or heart-shaped or like
drawn-out cylinders. Some are annuals and
others perennials. As to flavor, some are sweet
and palatable, while others are among the most
pungent and fiery of substances that are ever
purposely put.into the mouth.
My own work has included the cultivation and
crossing of a large number of species and varie-
ties of pepper. At least one of these will stand
a very low temperature, the plants showing no
trace of injury when left where ice forms a
quarter of an inch in thickness,
As most of the peppers are exceedingly sensi-
tive to frost, this hardy Chilean variety seems
to offer opportunities for hybridizing experi-
ments through which other varieties of the plant
which at present are of restricted habitat may be
made suitable for growth in colder climates.
In crossing the very small varieties with the
very large ones, and the very light-colored with
the very dark-colored, one produces the most
unusual combinations. Even in the first genera-
tion some bushes appear having diminutive
fruits and others having unusually large ones;
and there is a display of different colors, includ-
ing stripes, that is quite beyond prediction.
216 LUTHER BURBANK
Occasionally, though not often, fruit of dif-
ferent colors will appear on the same plant.
Some hundreds of varieties of pepper have
been described, but only perhaps less than a
dozen are cultivated ordinarily in the gardens of
temperate climates.
The large sweet peppers are becoming popu-
lar. In some varieties, they are almost mild
enough in quality to take the place of their rela-
tive the tomato.
There can be no question that selection among
these and breeding through successive genera-
tions would produce almost any desired com-
bination of qualities.
This chapter has been confined to the edible
forms of the lily, mustard, and potato families.
ARTICHOKES AND OTHER
GARDEN SPECIALTIES
Sine NEw Wiuip Foop PLants
IN THE Woops
OUBTLESS the greatest labor-saving
scheme ever devised by any flower to
meet its essential needs is that adopted
by the Sunflower family—the tribe popularly
represented by the sunflowers, asters, thistles,
and daisies.
The botanist classifies the members of this
tribe as Composite or Compound Flowers. The
name might be misleading if taken to imply that
the flowers of this family differ essentially from
other flowers. But the individual flowers of this
tribe are in all essentials of pistil and stamen
like other flowers. So the modern botanist
objects to the name “Compound” as applied to
them, although he retains the Latin title that
they have borne for some centuries.
But if we properly interpret the term, the
name “compound flower’ seems appropriate
217
218 LUTHER BURBANK
enough, inasmuch as what would commonly be
called a single blossom—say a single daisy, or
aster, or dandelion, or thistle—is in reality made
up of a very large number of individual flowers
grouped together into a floral community, which
advertises its location to the insects by arranging
a single circle of petaloid colored emblems that
do service for the entire community.
A MEASURE oF Economy
The economy of this arrangement, in the
matter of saving plant energy, is obvious.
Flowers that have not adopted this system are
obliged to supply a colored advertising emblem
for each individual set of stamens and pistils.
These composite flowers make one such floral
emblem serve the purpose of scores or even
hundreds of flowers.
Of course the floral community, even though
the individual flowers are very small, occupies
considerable room. It is necessary, therefore, to
provide a largish receptacle to hold the flowers,
and in particular to hold their seeds when
developed. The outside of this receptacle is
usually covered, for protection, by overlapping
series of scaly bracts or little leaves that form
a sort of armor. A glance at a sunflower will
illustrate the plan that has been pretty generally
GARDEN SPECIALTIES 219
adopted in the provision of a covering to shield
the flower village, particularly during its early
development. |
Eviste FLowrer Heaps
In at least one case a plant of the tribe has
been induced to develop this receptacle until
the leaves of its scalelike covering have been
enlarged and thickened and made succulent at
their base, so that they are edible; the receptacle
on which the flowerets grow being correspond-
ingly developed.
The flower that has thus been induced to put
itself at the service of man and add to the delica-
cies of his dietary is known as the artichoke.
This plant is widely cultivated in southern
Europe and is exceedingly popular there. In
Italy, indeed, it occupies in some regions about
the position in the dietary of the masses that the
potato does in northern Europe and America.
In this country, however, the artichoke has only
somewhat recently begun to gain popularity. As
the manner of its cultivation is better under-
stood, it will doubtless gain wider vogue, for its
leaf scales and pulpy receptacle are regarded as
delicacies by epicures everywhere.
I have worked extensively with the artichoke
in recent years, beginning with the French
ARTICHOKES
This picture shows one plant of the
thousands which are being improved,
taken just before the buds were ready
to burst. For table use the flowers are
never allowed to open, as the bracts
would then be practically inedible.
But these are intended for breeding
purposes and will, therefore, be allowed
to come to maturity, and the best of
them used for cross-fertilizing experi-
ments,
ist
f
as
GARDEN SPECIALTIES 221
Globe artichoke and the Oval Brittany arti-
choke in 1908; subsequently using also the Paris
artichoke, a large green variety, and of the
so-called Perpetual artichoke.
The plants when grown from seed vary
markedly in size and shape of the leaf as well |
as in size, shape, and quality of the blossom
buds. Some of the plants are thorny. The
flowers, if allowed to come to maturity, differ
little in color, though greatly in size. Some
of the newest flower receptacles when fully
matured open out to a breadth of twelve inches
and more.
But the flower bud is not permitted to mature
to the point of opening when the artichoke is to
be used as food. If it reaclies the stage when the
blue flowerets begin to be visible, the head is alto-
gether too old for eating. The object of culti-
vating new varieties is not necessarily to increase
the number of the flowers themselves, but in-
creasing the size and the quality of the scalelike
bud leaves and the receptacle.
My work has been carried out along the usual
lines of crossing and selection, and the results
have been very satisfactory. Selection has also
taken into consideration, as a matter of course,
the succulence and especially the flavor of the
edible portion.
222 LUTHER BURBANK
The improved varieties have flower buds as
large as a good sized fist, and are of excellent
quality. When in full bloom they are sometimes
a foot or more in diameter. ‘They are reproduced
with reasonable certainty from seeds, but the
method of propagation generally preferred is by
the use of suckers which the plant puts out freely.
Of course these suckers reproduce the qualities of
the individual plant from which they are taken,
as roots or grafting cions do in the case of other
plants. |
When it is understood by gardeners in general
that the artichoke can be grown with comparative
ease, and that it produces an abundant and never-
failing crop of healthful, palatable, and nutritious
food, this vegetable is sure to attain far greater
st aa ech THE CARDOON
The young stenis and leaves of the artichoke
plant itself are sometimes eaten in Kurope. It is
necessary to blanch them by covering, somewhat
after the manner of celery. There is a modified
form of the artichoke, known as the Cardoon,
which is cultivated for the stems and leaves in-
stead of for the flower buds. These are blanched
by tying the tops of the leaves together and cov-
ering the entire plant with straw, banked with
earth.
GARDEN SPECIALTIES 223
I have grown the cardoon, but have not experi-
mented with it in the attempt to produce varia-
tion, as the European cultivators have developed
it to a very satisfactory stage.
The plant is very little known in America, but
is likely to be more extensively propagated when
its merits are understood.
THe SUNFLOWER ARTICHOKE
Another member of the sunflower family is
popularly known as the Jerusalem artichoke, the
name having originated, it is said, in a Spanish
nickname, amplified to suggest the relationship
of the plant to the artichoke just described, which
is generally spoken of as the Globe artichoke.
The Jerusalem artichoke belongs to the genus
Helianthus, of which there are numerous species,
some of them growing wild in California. It is
entirely distinct from the true artichoke, both in
growth, appearance, and the purposes for which
it is used.
The part of this plant that is sometimes used
as food is not the flower bud, but a tuber not very
remotely suggestive of a potato.
The plants of the sunflower tribe are variable,
as is usual with plants represented by many
species. Some of them bloom abundantly when
only six to twelve inches in height, while others
HALF OPENED ARTICHOKE
BLOSSOM
This is an individual blossom of the
artichoke. The flower head has passed
the period when it would have been in
ideal condition for eating, but has not
yet fully presented its stamens and
pistils. The improvement shown in
some of these crossbred artichokes is
remarkable; and they are still wnder-
going development. Some of the newer
varieties produce blossoms four feet in
circumference. The most wonderful of
all is a perpetual variety of exquisite
quality.
GARDEN SPECIALTIES 225
grow to a height of ten to fifteen feet. They
have very large, broad, heavy leaves, and some —
of them produce sunflowerlike blossoms of enor-
mous size. |
Others have small, delicate, slender foliage, and
produce small flowers.
The flowers are yellow, the tubers are usually
pink, but white and red varieties have been pro-
duced in the past decade.
Some members of the Helianthus tribe are
perennials, but for the most part they are annuals.
They are all easily grown on almost any soil,
requiring little or no attention. The member of
the tribe known as the Jerusalem artichoke is a
somewhat variable plant, the tubers of which are
chiefly used as food for stock, although sometimes
used as a salad.
My own work with the tribe has been for the
improvement of both the flowers and the tubers.
There is one of the annual sunflowers that has a
flower quite often sixteen to twenty-four inches
in circumference that, if well selected, comes per-
fectly double, as double as the finest dahlia, pro-
ducing a most brilliant yellow bloom abundantly.
This I have worked on several years to make its
flower uniformly double. Also I have worked
with a large number of species of the tribe and
have cultivated many field varieties collected in
8—Vol. 5 Bur,
226 LUTHER BURBANK
Mexico, California, the Mississippi Valley, and
nearly as far north as Hudson’s Bay.
I have done a good deal of crossing and selec-
tion among the seedlings to increase the grace of
the plants and delicacy of bloom, and to make the
silvery, graceful leayes of one species replace the
rough, coarse leaves of another,
There is no great difficulty in hybridizing the
various species, especially if care is taken to
wash away the pollen by the method described
in the chapter on artificial pollination. But
there is great difficulty in fixing a variety
after it is formed. The hybrids tend to take
on many forms, their variability in the second
generation suggesting that of the gourd
family.
Of course this difficulty does not apply in the
case of the artichoke, as this is propagated only
from tubers, just as the potato is propagated.
So any improved variety developed is fixed from
the outset. There has not hitherto been enough
demand for the plant in this country to stimulate
the plant developer to work with it. But it is
probable in the near future there will be renewed
interest in certain less common garden vegeta-
bles, comparable to that shown in recent years in
the development of the orchard fruits, and in that
case the Jerusalem artichoke is almost certain to
ee ae
GARDEN SPECIALTIES 227
receive recognition as a neglected vegetable that
is worthy of being generally cultivated. |
During the past few years, among thousands of
crossbred seedlings, several have been produced
which, though as productive as the older varie-
ties, are delicious in flavor, while all those before
known had a resinous, sunflower taste, not gen-
erally relished. The matter of raising seedlings
from the common cultivated varieties was found
to be impossible, as they had been grown from
tubers so long that the power to produce seed
was wholly lost, yet a small amount of pollen was
sometimes available for use on the wild species
and from this these improved varieties were
produced.
Tue Lerruce TRIBE
Doubtless the best known member of the Com-
posite family under cultivation is the familiar
lettuce.
This plant has been so long under cultivation
that it is impossible to trace it back to the original
wild species and in token of its long cultivation,
it is one of the most variable of plants. There
are hundreds of varieties of lettuce described in
catalogues, but those all quite naturally fall under
two distinct groups—the cabbage or head lettuce
and the cos or upright growing lettuce, the latter
of which is mostly grown in cool, moist climates.
A WILD ARTICHOKE
It will be seen that this wild artichoke,
in full bloom, is hardly three inches
across. The flower head as a whole is
strikingly suggestive of that of the
thistle. This specimen gives a very
good idea of the flower from which the
modern improved artichoke has been
developed. Contrast this thorny little
flower with giant in the next. picture.
GARDEN SPECIALTIES 229
The cos lettuce requires too much care in
blanching, and in our dry American climate runs |
up too quickly to seed:in warm weather.
My work with the lettuce was done about ten
or twelve years ago, when I experimented in the »
endeavor to produce different forms, and _ at-
tained a measure of success. In working with the
cos lettuce the endeavor was to get a more solid
head which would be a very tender, compact
grower, and would not so quickly run to seed.
The part of the lettuce that is eaten is, of course,
the leaf, and the plant that runs to seed quickly
develops a toughness of leaf fiber that impairs
its value.
In hybridizing the lettuce, my usual plan was
to get two varieties to bloom as nearly as possible
at the same time, and to pollenize by bringing the
head of one and rubbing it against the flowerets
of the other. The pollen may be removed with a
dash of water, as already described, but there is
always a measure of uncertainty in cross-pollen-
izing composite flowers of such small size as those
of the lettuce, as one cannot be sure in many
cases that a certain amount of the pollen does not
remain to effect fertilization of some neighboring
plant, but any skillful operator should be able to
know when a cross has been secured by the
product.
230 LUTHER BURBANK
It was found feasible to combine some desir-
able qualities, but we did not succeed in combin-
ing all the desired qualities in a single variety.
There is greater variation as to flavor among
lettuces than is commonly supposed. Of course,
the different types are used for different pur-
poses and at different seasons. ‘Those grown
under glass must be compact growers, while those
grown in the open may be permitted to develop
larger heads. There are varieties of so-called
perpetual lettuce which have been so educated
that instead of running to seed they form new
heads that can be cut again and again.
As to all these matters there is room for great
improvement, and there is opportunity for the
plant experimenter whose experience justifies
him in working with a somewhat difficult species
to secure better varieties of this very popular
salad plant than any at present on the market.
DANDELION AND THISTLE
There are other wild species of the Composite
family, however, that offer greater inducements
to the cultivator. One of these is the familiar
dandelion, a plant usually regarded as a weed,
but really having possibilities of usefulness.
The dandelion is sometimes used as a green
vegetable in the early spring by country folk in