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

 

SOME COMMON GARDEN PLANTS AND THEIR IMPROVEMENT

HALF HOUR EXPERIMENTS WITH MANY PLANTS

Notwithstanding the large number of garden vegetables, all the common forms fall into a few groups. Thus there is the great family of melons and squashes, technically known as the gourd family, which gives us such familiar vegetables as the gourds and squashes, the pumpkin, the watermelon, and muskmelon, and the cucumber. Then there are the cabbages of various types, with which is botanically associated the turnip, and with which the gardener will also associate the familiar lettuce plant. Another group includes the familiar root vegetables, the carrot, parsnip, and radish. These have a characteristic manner of growth, demand somewhat the same texture of loose, sandy soil, and respond to the same treatment. In a quite different class are the peas and beans, which, in all their varieties, are obviously related to one another and quite as obviously distinct from all the other members of the garden coterie. The onion and its allies may be recognized as constituting a class of vegetables that supply savor rather than nutritious principles. From the standpoint of the gardener there may be listed a number of less familiar plants to make up the category of vegetables that are grown merely because of their appeal to the palate and for the flavor that they impart to other foods rather than for their genuine food value. Two other prominent plants which complete the list of the ordinary garden vegetables of greatest popularity are classed together by the botanist, and indeed are to casual observation closely similar in foliage, yet so distinct as to the character of their product that the gardener would never think of associating them. These are the potato and the tomato-own cousins-notwithstanding the widely different character of the food products they supply. Some of the plants just named will be given individual treatment in successive chapters of the present volume. But two or three companies, including a wide range of species and varieties, may be grouped together here as illustrating, jointly and severally, the methods of the plant developer when applied to garden vegetables, and as offering interesting possibilities of development for the amateur gardener.

THE MELON FAMILY

At the outset we may consider the melons, partly because the product that they offer the gardener may be said to occupy an intermediate place between the fruits proper, as grown in the orchard, and what are commonly spoken of as garden vegetables. The melons are, indeed, fruits of a distinctive order. They seem of unique type to us merely because our point of fact is that of residents of a temperate zone. In tropical regions, fruits like the melons abound, the family to which the melon belongs being a very extensive one, represented in the aggregate by several hundred species. The most generally cultivated member of the melon family in the ordinary kitchen garden is doubtless the form known as the cucumber. The ordinary cucumber has long been under cultivation and has been greatly improved, especially in Europe. It has been made to take on various forms of fruit, and the best varieties have been practically relieved from the spines with which the plant was originally endowed, and partially also of the seed. The common cucumber may be crossed with the variety known as the Russian cucumber, but in general this plant proves its individuality by refusing to hybridize with its not very distant relatives, such as the melons. But the other members of the family hybridize readily. Indeed there is so little difficulty in crossing them, that it is necessary to plant the different species in widely separated rows to prevent accidental hybridization through the agency of the bees. With the cucumber there is no such difficulty. In our experience it refuses to hybridize with other melons. Doubtless because of its lack of affinity for other species, the cucumber is relatively easy to fix as to new varieties, differing very markedly in that respect from the squashes and gourds. The so-called snake cucumber is in reality a muskmelon. It will cross readily with the other varieties of muskmelon. The product, however, is inferior, considered either as a cucumber or as a melon. The banana melon is probably a cross between the snake cucumber and some other muskmelon; or it may have originated from the same source as the snake cucumber itself. The banana melon has been improved by selection until in some varieties it is a fairly good melon, although generally lacking the high flavor of the cantaloupe and other specialized muskmelons Some varieties of these so-called snake cucumbers attain a length of three or four feet, and coil up in such a way as to resemble a serpent, justifying their name. A form of melon introduced, I believe, from Syria, and known as the Santa Claus melon has interest because it keeps well until mid-winter. It is a longish oval muskmelon, with red and green stripes. Its chief demerit is that it is variable in quality, some specimens being of delicious flavor and others distinctly inferior. It has the further fault of cracking seriously. In working with this variety during the past few years, I have succeeded in largely eliminating its faults, and in so doing have produced a type that might be considered a new variety. My work with the species has been entirely along the line of selection, for I knew the danger of producing too great variation by hybridizing the members of this family and the almost impossibility of fixing any variation. Most forms have originated by hybridization at no remote time in the past, and it is far better to work with them by selecting individuals that are observed to vary rather than by attempting to produce wider variation. By this method alone I was enabled in a few years to develop a form of the Santa Claus melon that was considered worthy of introduction. The company that purchased it have renamed it the Florida, and are planning to grow it along with other products on a large tract in Florida. Not only is it necessary to keep the muskmelons in different parts of the garden to prevent crossing through the agency of insects, but it is also necessary to be exceedingly careful in selecting the seed year after year, saving only that from vines that come true to type. Otherwise the stock soon runs out and comes to lack individuality of form and flavor of fruit. This is because the muskmelons have been cultivated for a very long period and have developed many varieties that have constantly been more or less crossed. This mixed heredity is likely to make itself manifest in the progeny of any generation, and constant attention is necessary if a type is to be kept pure. The muskmelon grows best on sandy land, and of course a warm climate is necessary to the perfection of the fruit. It acquires a particularly sweet, spicy flavor where the nights are warm as well as the days. In recent years the small, green-fleshed muskmelon, generally called cantaloupe, has become exceedingly popular. The variety of melon known as the Casaba, which matures later in the fall and has peculiar lusciousness, is also much grown. This has been introduced from the Syrian region in various forms, and it thrives particularly in dry climates like that in which it has grown for ages. It does not thrive in the moist eastern climates, but is better adapted to semi-arid conditions. There are certain distinctive features of the different cantaloups and muskmelons to which the gardener should give attention. The light-fleshed ones should have light skins, and the dark-fleshed ones dark skins. The network on the skin is an important guide in seed selection, as a fine, completely netted melon usually is of better quality than one that is incompletely netted. These two conditions seem generally correlated, though not necessarily so. The flesh of the melon should be thick, and tender throughout, except that for shipping purposes it is sometimes desirable to have the flesh a little harder toward the skin. The seed cavity should be small, and the seeds should be in a compact mass, occupying a minimum amount of space. Now and again one hears of attempts made to grow seedless melons. A moment's reflection will show that this suggestion must be intended as a joke. The melons are annuals, and must be grown year by year from the seed. To eliminate the seed would be to exterminate the melon in a single season. The case is obviously very different from that of fruit trees, which may be propagated by grafting, or of such plants as the horseradish and potato, the roots or tubers of which carry the species over from one season to another. In raising melons, especially in colder climates where the seasons are short, it is desirable to use ammoniacal fertilizers to force the plants along rapidly. A liberal use of one of the nitric fertilizers will often double the crop or, indeed, insure a crop where otherwise the melons would not ripen. The gardener who wishes to grow melons extensively will not overlook the pomegranates and so-called orange and pocket melons. These have interest because of their unusual appearance, even though they are somewhat lacking in quality. There are also large Persian and Syrian melons that are favorites not only for their delicious quality but also because they keep until late in the winter, even until the first of January with common storage. Probably in cold storage these melons would keep throughout the winter. Unfortunately these Persian and Syrian melons are exceedingly variable as to quality. Some are fully equal to the best cantaloupe, while others will be hardly edible. The amateur gardener might find it a useful and interesting task to improve these melons in this regard by careful selection. The squashes, gourds, and pumpkins constitute a tribe of melons that differ from the watermelon and muskmelon in that their flesh is not edible until it is cooked. There are great numbers of species of this tribe, a large variety of which are under cultivation. Among these are the forms colloquially known as crookneck, turbine squash, giant Chile Hubbard, bush scallop, and gourds of various types both ornamental and useful. The pumpkins, grown often in the cornfield of the farmer but seldom in the garden, constitute a form of squash rather distinct from the others, as evidenced not only by their appearance but by the fact that they do not cross readily with the other squashes. There is, however, a good deal of confusion in the use of the names pumpkin and squash in different regions. This is brought out prominently in California where a squash if grown for stock food is called a pumpkin, whatever its variety. The earliest form of squash with which I worked was the winter or Canada crookneck, which in my boyhood was one of the most popular of squashes. It had run into several forms, one being of immense size with a short and heavier neck. The summer crookneck squash, also common at that time, was a long, bright yellow, warty squash, grown for summer use. Another form, somewhat less familiar here but very popular in England, is the vegetable marrow. The scallop or Pattypan type of bush squash has also attained popularity in some regions, being an especially early variety. There was a squash introduced some years ago under the name of cocoanut which was a splendid keeper, lasting from harvest time to harvest time, although not improving in quality after the first six months.

THE HUBBARD SQUASH

The Hubbard squash was introduced by J. J. H. Gregory, of Marblehead, Mass., and it is probably on the whole the best squash now under cultivation. It is of a very rich, sweet quality and is a splendid keeper. Mr. Gregory obtained the first seed of this squash from the garden of a sailor's widow, and no one has ever found the Hubbard squash in any other country except as introduced from this stock. It was never known where the sailor obtained the seeds that produced it. Reference has been made to the ease with which the various squashes may be hybridized. In point of fact it is necessary to grow squashes of different species at a distance of nearly a quarter of a mile or there is danger that they will be cross-fertilized and the strains rendered impure. So of course the plant developer has no difficulty in effecting almost any cross he may wish. It is only necessary to take pollen from one flower and deposit on the pistil of another to have reasonable assurance that the cross will be effected. But the results of such hybridizing are usually altogether disconcerting. The hybrid progeny seem to branch in every conceivable direction. A gardener of mine declares that hybridized squashes "go crazy", so widely varying are their forms and so little subject to prediction. Moreover, it is exceedingly difficult to fix any new type thus developed or to restore an old type thus disturbed by crossing. Even if the hybrids do not vary greatly in the first generation they may become entirely chaotic in the second. A classical illustration of this is furnished by some experiments of Prof. L. H. Bailey, who developed a variety by crossing that seemed to come reasonably true to type one year. Thinking the variety fixed he sold the seed to a prominent seedsman, and it was said that the following year no two specimens of the entire lot bore any close resemblance to each other. This happened a good many years ago, and was so disconcerting as to lead Prof. Bailey for a time to question whether the laws of heredity apply to plants as they do to animals. Needless to say all doubt on that subject was dissipated by wider observation. But the hybrid squash remains to this day one of the most difficult plants to fix as to any particular form. Some very interesting and useful experiments might be made in the endeavor to sort out the unit characters that are mosaiced together to make up the squash. If it could be determined that there are pairs of unit characters governing important matters of size and quality, such as are found in so many other plants, an understanding of these as to their respective properties of dominance and recessiveness might enable the plant developer to hybridize the squashes and forecast the results of certain unions with a greater measure of assurance. But as yet little or nothing has been done in this direction. My own work with the squashes has included hybridizing experiments on a somewhat extensive scale, more for the general interest of the subject than for the development of new commercial varieties. I have produced, however, one somewhat important variety from seed sent by my collector in Chile. This is a variety the original of which somewhat resembled the acorn squash-having the form of a rather irregular acorn in its cup, giving it a unique appearance. This is of very large size and it will grow on dry land where other squashes do not thrive, attaining a great weight. The vines first grown from the seed showed evidence of mixed ancestry. But some of them gave such promise that it seemed worth while to sort out the best strains. To effect this, I used hand pollenation and the most rigid selection. Only the specimens showing the desired qualities were used in the crosses, and only the best individuals preserved for seed. In the course of a few generations a fairly fixed plant was thus produced. The most marked peculiarity of this squash was its exceptional specific gravity. For its size it was incomparably the heaviest squash I have ever seen. The meat is thick, solid, and of dark color. Its seed cavity is of medium size, thickly studded with large, heavy seeds. Exteriorly the squash is white, striped with green, generally but not always smooth. This new variety found favor in many localities for planting in dry places or as a dependence in dry seasons. It was named the Chiloe by the company who introduced it, in recognition of the home of the ancestral stock from which it was developed. Notwithstanding its cannon-ball like solidity, it is of exceedingly sweet flesh. Its firmness gives it remarkable keeping qualities; it often lasts until May or even June of the following season. My work with this squash shows that it is by no means impossible to fix a new type. But there is abundant work to be done in this direction with large numbers of varieties now under cultivation. Much may be done also toward developing thickness of flesh and sweetness of quality. Moreover, attention should be given to the seed cavity, which may be made much smaller. The seeds cannot be altogether eliminated but their number might be advantageously reduced. Again, varieties may be developed having shorter or more compact vines. There should be no great difficulty in attaining these ends, and the field is obviously one in which any amateur gardener may work with ease. The facility with which squashes may be hybridized gives them added attractiveness from the standpoint of the novice.

THE CRUCIFER FAMILY

The tribe of Crucifers is represented by a large number of annual and perennial herbs of wide distribution, the most conspicuous members of which are the cabbage and its allies. It is supposed that all of the near relatives of the cabbage are modified descendants of a single species that grows wild along the Mediterranean and Atlantic Coasts of Europe. Turnips are descended from another closely related species having the same habitat. The radish, horseradish, water-cress, and mustard are other members of the family that are not quite so closely related. The members of this group occupy a position of considerable importance in the vegetable garden; chiefly, however, because of their various flavors rather than because of their nutritious value. There is comparatively little nourishment in the substance of any of them, except the cabbage. From the standpoint of the plant developer, the members of the cabbage tribe have exceptional interest, not so much because of possibilities of future development as because of what they reveal of past development. If, as is believed, they have all sprung from a single species and within comparatively recent times, they afford highly interesting illustrations of the varied lines of development that the offspring of a single plant may be induced to follow. Thus the edible head of the cauliflower and broccoli consist in reality of thickened and consolidated flower peduncles. The edible part of the kale consists of expanded but tender leaves. Brussels sprouts are thickened buds developed in the axis of the leaves. The cabbage is merely a single monstrous bud, with its leaves unexpanded. And in the kohl-rabi-perhaps the most recently developed of all the garden vegetables-it is the short and few-leaved stems that become thick, bulbous, and edible. Here, then, is a plant in the different races of which, the stem, the leaves, and the flowers respectively have been modified until they are edible monstrosities. Few other plants show such versatility; so the familiar colloquialism that dubs a dunce a "cabbage head" is obviously lacking in fitness of application. If the cabbage tribe were to develop a member having an edible root, its versatility would be universal; and, indeed, a very near relative belonging to the same genus makes up the deficiency in this regard: for the turnip has about as much root in proportion to its size as a plant can possibly produce. As might be expected, considering their origin, the different crucifiers vary greatly. The various cabbages and cauliflowers and Brussels sprouts may be hybridized with one another or with the strap-leaved turnips without difficulty. But the result is usually a rather curious lot of mongrels that have no utility, all apparently tending to turn back toward the wild parent form. Each member of the family has been developed to its present specialized form through many generations of selection alone; and the specialization is so great that there is small prospect 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 day of my experimental work, nearly half a century ago. I discovered 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 to describe as mongrels. Some of them had small cauliflower heads of inferior quality. At the time when these experiments were made I did not fully understand the importance of the second generation, and I have never found time to take this line of experiment up again. I have had good success, however, in crossing the purple-leaved cabbage with other varieties of cabbage, developing thus a purple cabbage with a very large head. They were somewhat less dark in color than the parent stock. My work with the turnip has not extended beyond the stage of experimental crossing with the cabbages, which led to no prospect of useful results. With the radish, which might be described as a dwarf turnip, my work has been carried along the line of selection, without hybridizing. There are enough variations among the seedlings of any given root 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 radishes 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. I also gave attention at one time to the flavor of the radish, developing the sweet pungency 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 re-selected persistently for several years showed a tendency to reversion. But this variability, while it is annoying 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 root or 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.

THE ORIENTAL RADISH

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 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 tendency 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 develop a poisonous quality. But as ordinarily grown from the seed and pulled in their 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 I found this 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 unwilling 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 instincts, 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. I have also found that color can be added to the carrot root or taken away from it by selection through successive generations. This is quite what we might expect when 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 undertake the improvement of both parsnip and carrot as to the quality and shape of their roots, and such experiments might very likely prove successful if carried out persistently, notwithstanding my failure to produce marked modifications in this regard. The flavor of the carrot could also be improved, probably without great difficulty.

SALSIFY OR OYSTER PLANT

There is another root that offers a challenge to the plant developer somewhat as do the parsnip and carrot, by the very fact of its obstinate resistance to any change. This is the plant called the 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 horticultural 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 Mammoth 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 cultivation. 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 members 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. Possibly through selective breeding, based on such hybridizations, new varieties of salsify might be developed and the plant might thus conceivably be made to occupy a much more important position than it does at present among garden vegetables.

This text is from: Luther Burbank: his methods and discoveries and their practical application. Volume 7 Chapter 2