ORNAMENTAL PALMS AND CLIMBING VINES
VIEWS ON ARTISTIC TREATMENT
Visitors from the East are often surprised to find palms growing thriftily at Santa Rosa. The average resident of northern latitudes appears to associate the palm with tropical conditions. And while it is known to everyone that these trees grow in Southern California, it seems a matter for wonderment that they should be found so far to the north as the region in which my experiment gardens are located. In point of fact, isothermal lines make no difference in California, as the winds from the Pacific, deflected by the mountains, determine the climatic conditions, and produce quite unpredictable results. Thus it is that oranges are sold from northern California before they are ready to pick in the southern part of the state. And again, the palm is a relatively hardy tree, I mean, of course, in comparison with tropical plants in general. And whereas the date palm does not thoroughly perfect its fruit, for the most part, except in regions where the summer is very long, this tree may withstand extremes of temperature that are widely removed from anything experienced in the tropics, and other palms generally perfect their fruit wherever they can be grown. Indeed, so hardy are some of the palms that the question arises whether it may not be possible by selective breeding and adaptation to develop races of palms that will thrive even in the middle latitudes of the eastern United States, and far to the north of their present limits on the Pacific Coast. The fact that most of the palms now growing in California have been introduced within comparatively recent times, and that they have gradually made their way northward, is suggestive of the possibility of much wider extension of their habitat. A difficulty in the attempt to carry out any project in selective breeding calculated to give the palm additional hardiness or any other quality is found primarily in the fact that this tree does not mature its fruit until from ten to twenty-five years of age. But in recent years an effort is being made by the Department of Agriculture and by several private individuals, to introduce races of date palms that will bear marketable fruit, and the study of the palm that has been undertaken in this connection will doubtless lead to important results, Even now it has been demonstrated that just as good dates can be grown here as in the Sahara. It appears that the palm, notwithstanding its relative fixity, is subject to considerable variation, and that this is particularly true of the date palm fruit, as might be expected considering that this tree has been under cultivation from pre-historic periods, and because it has been selected for the fruit alone. The most delicate and delicious date fruits are not the ones that can be secured for export, so that these varieties can never be seen on the American market until they are grown here. All the best date palms, unlike most other palms, are grown from suckers which come up from about the roots of the tree. To be sure, the Oriental peoples, for whom the date has supplied a most important food product from the earliest periods, have probably paid very little attention to selective breeding. Still the broad general fact that "like produces like" has been matter of common knowledge from remotest antiquity, and it can hardly be doubted that a certain amount of more or less intelligent selection of the trees that bear the best fruit, with attempts to raise seedlings from these trees and thus secure races of good fruiL-bearers, has been practiced, generation after generation. Moreover a certain amount of cross-pollenizing between allied races of palms has doubtless taken place without the agency of man, and so it is all but certain that the different palms under cultivation bear mixed racial strains, somewhat as do the different races of orchard fruits and cultivated plants of temperate climates. It is quite to be expected, then, that the palms grown from the seed should show a good deal of variation. That such is really the case is made obvious to anyone who attempts to raise them. The date palm, for example, may readily enough be grown from the seed, for the seeds germinate readily, though slowly. But the tests have shown that the progeny of a date palm bearing fruit of the best quality cannot be depended upon to transmit the characteristics of the parent with a high degree of certainty. So it is necessary to grow the young trees from suckers if the strain of the parent is to be perpetuated accurately. The experts of the Department of Pamnology at Washington and several private individuals, have imported rooted suckers, obtained from female trees known to produce fruit of excellent quality, distributing them and planting them in various regions of the southwestern United States. The trees that grew from these suckers have proved to be pistillate, as expected, and produced fruit equal to that of northern Africa. Considerable difficulty was experienced in securing suckers from the best trees, even private individuals not being allowed to own them in the original country. As to the date palm, the progress already made in the improvement of the fruit indicates beyond the shadow of a doubt that still further improvement will be made in many directions. It is probable that the colony of fruit-bearers thus introduced will spread indefinitely, until the date palm becomes an important economic tree in warmer portions of America. It is even more important with the palm than with other fruit-bearing trees that propagation should be carried out in this way, because when the plants are grown from the seed only half of them will be bearers of pistillate flowers. The pollen-bearing trees will of course bear no fruit, and while there must be here and there one of these in the palm grove-one pollenate to about twenty-five pistillate trees-it would be an obvious waste of space to give over half the ground to sterile trees. Yet there is no way of determining whether an individual tree is a male or a female until it comes to the age of blossoming; and the palm is a tree of slow growth that matures only after a good many years. But trees grown from suckers will be of the same sex as the parent trees; hence the double utility of propagating by tEhis method.
PALMS FOR ORNAMENT
From the standpoint of the present chapter, however, the fruit-bearing qualities of the palm are not so much in question as its ornamental character. Considered merely as ornamental trees, there are members of the genus Phoenix, to which the date palm belongs, that are more attractive than this famous fruit bearer. And in general the character of the form and foliage of a date palm is carried with sufficient certainty from parent to offspring by the seed to make it perfectly permissible to raise palms fromi the seed for ornamental purposes. Even where the seeds are planted in rows, with the expectation of producing colonnades of palms, along road sides or for borders, the palms may be grown from the seed without danger that they will vary sufficiently to interfere with the symmetry of the row, provided the seed are gathered from the same -tree, or at any rate have come from the same region. If, however, the seed be inported from different regions, there is probability of a good deal of variation even among trees of the same species. The more usual method, however, in California, is to germinate the seed in a hothouse, growing the young plants in pots at first, and then removing them to boxes that they may be more readily transplanted, as they make slender, wiry roots. They are as easily grown as kernels of corn, though requiring much longer periods of time. Occasionally, however, they are planted in nursery rows, and it is sometimes desirable to transplant them after they have obtained a growth of twenty or thirty feet in height, and a diameter of trunk of one or two feet. In such a case, it is necessary to cut around the roots of the tree some time before removal, making a ball of earth that is to be removed with the tree. This treatment induces the palm to throw out new roots, giving added firmness, and making provision for the rapid absorption of moisture and nourishment after transplantation. A box being constructed around the soil, the palm may be removed to any distance. Sometimes a single palm thus transported is of such size as to require an entire flat car. But unless the precaution is taken to cut back the roots and allow them to stand for some time before removal, as just suggested, there is danger that the palm will die after transplantation, because the loss of its long roots makes quick adaptation to the new conditions impossible. The Phoenix canariensis is a thoroughly hardy palm in this climate, and the handsomest of the hardy members of the tribe. It is therefore the one most used for planting for ornament in California, though the Chamaerops excelsior from Japan is as hardy and next most common. The Canary palm grows with great rapidity after the plant has the first five or six leaves, although like all other palms its early growth is slow. An ordinary specimen of this species, transplanted into good soil in this region when it has four or five leaves, will grow to a height of fifteen feet, with a corresponding spread of branches, and develop a trunk eighteen inches in diameter in six to ten years. No other palm with which I am acquainted will make more than about one-fourth this growth in the same time and under the same circumstances. There is considerable difference in appearance, however, and in rapidity of growth of different strains of palms of this species. Yet the seedlings are unusually true to type, so that long rows of the Canary palms may be grown from the seed with full assurance that they will not vary sufficiently to break up the general uniformity of the row. Palms of the genus Chamaerops are also very hardy, perhaps even hardier than the Phoenix palms. I have never known one of them to be injured by frost anywhere in California, even when quite young. There are several species of this genus. I have grown them from the seed somewhat extensively, and have noted a wide variation among different species, some making large trees, while others are dwarfs, some of which, in this region, never attain a height of more than three or four feet. One exceedingly thorny species may be multiplied by division readily, as it throws up suckers abundantly around the old plant, unlike most other palms. Some accidental hybrids have appeared among the species of Chamaerops.
VARIATION AND DEVELOPMENT
Notwithstanding the considerable variation among the different strains, there is almost no discoverable variation in seedlings of a species of this genus of palm when grown from seed of the same tree. The species most commonly grown in California is C. Excelsa. This is a species that in China and Japan is one of the most useful of trees, its foliage being used for thatch, the rigid leaf stalk for braces, and the woolly substance about its trunks for cordage and other purposes. Moreover this is the palm from which fans are usually made, the undeveloped, immature leaves being used for this purpose. The palms of this genus usually bear the stamenate and pistillate flowers on different trees, but it is not unusual to find a few stamenate blossoms on pistillate trees, or, contrariwise, a few pistillate blossoms on stamenate trees. This, however, is a matter of no great practical importance, since the trees are grown in this region only for ornament, and it is not necessary to raise them from the seed, as they put out suckers abundantly. On the other hand, if the attempt is to be made to hybridize the different species with the hope of developing hardier races, the matter of fertilization of the flowers becomes obviously important. It will be worth while, then, to select the trees with reference to those that tend to mature their fruit early. But the work of developing a race of hardy palms will necessarily be a slow one, requiring the co-operative labors of successive generations of plant experimenters. And whereas it is probable that in the course of a century or two hardy palms will be developed, so that the question of selection of ornamental palms will be of interest even to residents of the middle and perhaps even of the northern regions of the United States, at the moment the matter can have practical interest only for a limited number of people, and we need not consider it more at length here. It suffices to say that the methods of hybridizing and selection that have proved successful with other plants will doubtless be found to have full application to the palm; and to add that the actual work in this field has been begun only in a tentative way. The method of hybridizing is simplicity itself-as simple as crossing two varieties of corn. Meantime, however, the palm exists as an ornamental tree of the very greatest value in California, and the interest shown in it by tourists justifies the expectation that in the near future, efforts of a comprehensive character may be made, probably under government supervision, to develop races of palms that can be grown far to the north of the present limits of this tree in the Eastern United States. A drive along Grange boulevard in Los Angeles, for example, and inspection of its rows of palms, alternating with pepper trees, gives the visitor from the East a mental picture of the possibilities of this race of trees for ornamental purposes that should certainly stimulate a spirit of emulation. Interspersed among pines-their brothers of pre-historic tinmes-they will be particularly appropriate and look especially well. The ornamental value of palms for roadsides and borders, and artistically placed here and there on the lawn, is admirably supplemented by a background of vines growing on walls or over rustic arbors or pergolas. And of course there are numerous vines, as everyone is aware, that flourish abundantly in regions where the palm cannot be grown. So the picturesqueness of effect that can be gained by the use of vines sometimes better than in any other way is available for the residents of northern climates, even far toward the arctic circle, almost as fully as in the sub-tropical regions. Among the vines that are so thrifty that they will grow in almost any soil, and so hardy as to resist the coldest winters, the so-called ivies of the genus Ampelopsis take foremost rank. Of these the Japanese Ivy, sometimes known as Boston Ivy (A. vitchi) and its varieties, is probably the best known and the most extensively grown. For the purpose of covering brick and stone walls it is perhaps the most beautiful of all vines. This vine has a close rival, however, and in the opinion of some even a superior, in the native species familiar everywhere in the middle and eastern states as the Five-Leafed Ivy or Virginia Creeper. This vine, however, does not cling to flat, smooth surfaces as does the Asiatic species. The strains of this vine differ materially in different localities, there being one in particular, named the Engelmann4, which clings to walls and trees better than the ordinary varieties. Vines of this variety are also far ahead of others in their rapidity of growth and in the beauty of their foliage, and especially in their autumn coloring. Some varieties hold their foliage nearly a month longer than others. These variations should be borne in mind in selecting plants for the covering of walls or making of arbors. The vines growing wild in Colorado are, in my opinion, much superior to those of the eastern states. I have raised thousands of seedlings of both species of Ampelopsis just named, and many specimens of other species known respectively as A. heterophyla and A. arborea, and have attempted to hybridize them, but only recently succeeded. The Japanese Ivy and the Virginia Creeper have now been crossed by me, and it is expected that the combination will produce varieties of priceless value, giving opportunity for the development of new races or ornamental vines to add to the comparatively limited number now available. The work is being carried forward on a large scale. It is probable that the Ampelopsis and the grape may be brought into combination. Meantime, I have developed a new variety of Virginia Creeper through selection that has much larger foliage than the ordinary varieties, and that is also a much more rapid grower, with the habit of holding the foliage to a late period in the autumn. As the plant is readily propagated by cuttings, such a new race as this may be distributed indefinitely.
THE BEAUTIFUL CLEMATIS
These vines are grown chiefly for their beauty of foliage alone, although the grape-like berries of the Virginia Creeper are not without some decorative value. There are other vines that in some respects rival the Ampelopsis as climbers for the covering of walls and arbors, and that have the added merit of producing beautiful flowers. Notable among the vines that have this double attractiveness are the various species of Clematis. There are several native species of the Clematis, and the plant has been brought sufficiently under cultivation to develop a propensity to vary. Nearly all the species are rapid climbers, and produce beautiful flowers in astonishing abundance. In addition some have feathery seed-pods that are scarcely less attractive and interesting than the blossoms that precede them, making an artistic contrast with the foliage for a considerable period. So all in all the clematis must be ranked among the most beautiful of vines. My work with the members of this tribe has been largely with the types that are known horticulturally as Jackinanni lanuginosa. These have large blue and white flowers, sometimes inclined to red and pink. I have raised these plants very extensively from the seed for many years. By selection, several varieties were produced that bore very handsome double flowers of peculiar form, varying in color from blue, pink, and ashy gray to pure white. Some of the new varieties also have exceedingly large broad petals with the flowers of unusually rounded outline, not unlike the form of a dahlia. Several of the best varieties of these improved Clematis vines were introduced through a dealer. But it was subsequently related that the clematis disease had destroyed most of these. This disease is a kind of rot, usually ascribed to the same cause that destroys lilies and many other plants in cultivated soil. It is probably bacterial, and is always associated with thrips, millipeds, and eel-wornms, which probably serve to disseminate the germs. Subsequently I began a series of hybridizing experiments, using the Clematis coccinea as the original seed parent. This species is herbaceous and has scarlet, flask-shaped flowers, with the sepals slightly opened by the curling outward of their tips. The sepals are thick and fleshy, although not leathery, giving the flower almost the appearance of a fruit. This species is almost invariable, about the only diversity noticeable being a slight variation in the size of the flowers. To the pistils of several specimens of coCCinea was applied the pollen of various other species; among these being C. crispa, known as "Blue Bells", C. Davidianua, C. Fremonti, C. ligasticifolia, C. Bouiglasi, C. verticillaris, C. occidentalis, C. Fortunei, C. Viticella, and others, no attempt being made to keep the various crosses separate. The hybrid progeny showed a great amount of variation, especially as regards color of the flowers. There were blue, crimson, scarlet, and white flowers, and sometimes all of these colors appeared in a single blossom. There was also much variation within certain limits in the form and texture of the flowers, which in general were of a larger size than those of the seed parent, and more spreading and widely open in form. Some had thick sepals and some had thin ones. Perhaps the most striking peculiarity was that the interior of the sepals often had a frosted appearance, due to the presence of a filament network of papillae. There is something of this appearance occasionally in flowers of C. coccinea and C. crispa, but it was much accentuated in many of the hybrids. In their general habit and their herbaceous stems, the hybrids seem uniformly to follow the seed parent. The flowers were produced in great abundance, and the colors were not only most beautiful but showed combinations never before seen in the clematis. The bell-shaped flowers are for the most part white on the inside, but exteriorly they are crimson, pink, orange, blue, or purple. The beautiful frosty throats give the flowers an appearance that is unique. I selected among the hybrids a few of the most beautiful forms, and placed these, without specific names, with a florist, Mr. J. C. Vaughan of Chicago, for introduction. Some of my earlier clematis introductions had been given names more or less suggestive of their peculiarities of flower, including "Ostrich Plume" and "Snow Drift". Another had been named "Waverley". I have stated that the earlier varieties were destroyed by the clematis disease. In the later experiments I endeavored to produce varieties that would be immune to disease, as well as those that would show exceptional hardiness. Several years ago, while on a trip in northern Canada, I found patches of clematis on half-woody slopes, growing in a region where the thermometer sometimes goes fifty or even sixty degrees below zero in the winter-regions where the deep wells do not thaw out altogether during the entire summer, always having a coating of ice about their walls. The hardy clematis found in this region bears dark blue flowers that are fully three and a half inches in diameter, being about as large as those of the cultivated varieties known as the blue Jackmanni, the blossoms of which they also resemble in color. There are two or three wild species in the same regions, namely C. Fremonti and C. ligusticifolia, plants that bear rather inconspicuous flowers of a greenish white color, but having long, feathery seed coverings that give them interest, and being in addition strong growers. I have already named these among the species of clematis that were used in hybridizing experiments. It was to be expected that plants having strains of such hardy species in their heredity would develop some varieties of great hardiness. And in this the expectations were not disappointed. A more extended series of experiments than I had planned to undertake would be necessary to fix the new varieties, and to make sure as to which of them are the hardiest. There is still opportunity for fine work in this direction. The clematis is so beautiful a vine, and there are so many species available, and among these species such amazing variety of form of vine and flower, that the opportunity for extensive breeding experiments with this type is most inviting. In raising the seedlings my practice was to sow the seed quite thickly in boxes in the greenhouse, as soon as it ripened in the fall, forcing the plants throughout the winter, and transplanting them in the open field in the early spring. The seedlings would make vines from eighteen inches to two feet long the first season. They would rarely bloom the first year, but in the second season they would almost invariably do so and the general character of their flowers could then be determined. But the blossoms of the first season would not fully represent the possibilities of their mature production. For example, plants that first bear blossoms that are semi-double would in later seasons, when the vines had gained in strength, bear fully double flowers. At the time when my first hybrid double clematis flowers were produced, there was, I think, but one other double one known anywhere in the world, this being a form produced in England. More recently, however, several good double varieties of this class have been introduced. The clematis is a plant that improves with acquaintance. Existing varieties furnish vines that are beautiful in foliage, in flower, and in their picturesque display of seed-pods. There is a great variation among the forms already under cultivation, but there is still abundant opportunity for improvement with these; and in addition wild species may be found that through hybridization will certainly introduce tendencies to still wider variation. What plant could offer greater inducements to the would-be experimenter?
BIGNONIA, WISTARIA, AND BELL-FLOWER
Of the numerous other interesting ornamental vines with which I have worked more or less extensively, I must content myself with mention of only two or three. Not that there is lack of interest, but to detail my wtork with them would involve a needless repetition as to methods. The work with the clematis may be taken as typical, and as representing one of my most extensive single series of experiments in connection with the ornamental vines. There are two or three other groups of vines, however, that must be given at least passing notice. One of the interesting forms with which I have done a good deal of work is the tribe of climbing shrubby plants of North and South America of the genus BigRonia. I have hybridized some species of bignonia with several of the Tecoma, a plant that grows wild in Virginia and Maryland. The resulting vines were variable, and had a fair degree of interest. There was modification of color of flower, length of seed-pods, and vigor of growth of the plants themselves. But no variety was secured that seemed worthy of introduction. An interesting feature of the hybridizing experiments with the bignonia is associated with the curious sensitiveness of the stigma of the flower to irritation. The two lips of the stigma stand open, like a set trap, and when pollen is supplied they close, trap-like, grasping it instantly. Anyone who has never seen the lips of the stigma of the bignonia close when irritated by bees or artificial means would be greatly surprised. It is necessary in applying the pollen to be somewhat dexterous, lest the lips of the stigma close and make the stigmatic surface inaccessible. Nor may the lips be pried apart. They open spontaneously, however, after a time, but usually not until the patience of the operator has been exhausted. It is a curious and interesting experiment to irritate the stigmatic surface with a grass stem or twig, which will be grasped as the traplike stigma closes, and held as a frog might hold a stick in its mouth. The same remarks apply also to the unrelated mulus, or monkey flower. Good work may be done by crossing the hardy bignonia with the tender ones, with excellent prospect of producing new varieties of value. Another ornamental vine that offers good opportunities for the plant developer is the familiar and beautiful Wistaria. There is a fair degree of variation among the different species of wvistaria, some bearing blue flowers and others white ones. The plants of this genus are not only valuable as climbers, covering walls and arbors with vines that bear beautiful flowers, but they can also be trained to form tree-like bushes that are most attractive additions to the lawn. The Chinese wistaria is ordinarily a long vine, but may be trained to a bush five feet across and thrive fully as well. Under this mode of culture, a certain amount of energy that would ordinarily go to the production of the vine itself is saved and utilized for flower production, so that wistaria bushes thus trained become astonishing bearers of blossoms, like gigantic bouquets. Nothing more is- necessary in training the vine than to trim it to form a head, and then from time to time to cut out the straggling branches. The wisterias are difficult to hybridize, because their flowers are papillionaceous, like those of the peas and beans. But with a little care, hand-pollenation may be effected, and some very striking variations should be obtained in the second generation from a cross, for example, between the American and Chinese wistarias. A complex hybrid between these species and the Japanese variety, Wistaria inaltiguga, which produces astonishingly long racemes of flowers, should give results of additional interest. My own experiments with the wistarias have consisted of the growing of a great number of seedlings, both of the Chinese and American species, selecting among these for plants varying in form, and bearing blossoms of different size and colors. The results of these experiments show that the wistaria is an adaptable flower, and one that is almost certain to repay more extensive breeding experiments, in particular those that introduce the element of hybridization. I will name only one other type of ornamental vines, this being the Lapageria, or Chilean Bell-Flower. As an excuse for selecting this one among many tropical and sub-tropical forms, I may say that when I first saw the Chilean bell-flower I thought it the most beautiful flower of any kind that I had ever seen. It has glorious, great, drooping, bell-shaped, rosy or white blossoms, which no lover of flowers could fail to admire. The foliage of the plant is smilax-like, and somewhat deficient in quantity, but the wonderful flowers make amends for any defect of foliage. Unfortunately the plants are very difficult to raise, needing peculiar soil and much attention. They are also sensitive to changes of temperature, and do not bloom at an early age. Moreover they must be kept moist at all times to insure good growth. The possibilities of work with plants of this genus are shown in a remarkable cross said to have been made by Veitch between one of the Lapagerias and the Philesia buxifolia, the latter being the pollen plant. The hybrid which has been named Philegeria Veitchii, is of exceptional interest, inasmuch as the parents belong to different genera. In scientific interest it ranks with the blackberry-raspberry hybrids, and the cross between the amaryllis plants and their remote relatives. As illustrating the possibility of the production of interesting new forms, I may note that a collector in Chile sent me a few years ago several species of plants allied to the Lapageria, but unclassified as to species, that very much resemble the English Ivy and that show exceptional habits of growth. One of these is said to bear excellent fruit. At three years of age, when the first blossoms appeared, the strongest plants were about fifteen feet high. Among the thousands of seedlings, there is enough difference in the form of foliage, rapidity of growth, and other characteristics to show that the plant is susceptible of improvement even in the first generation of seedlings from wild stock. Experiments in hybridizing these new plants with Lapageria, and further experiments in selection, in the hope of securing a new vine that combines with other good qualities the property of fruit-production, are contemplated. As yet this series of experiments is only at its beginning, but I mention it as illustrating one of the many lines of investigation, looking to the development of new varieties of ornamental vines, that invite the experimenter.
-The clematis is a plant that improves with acquaintance. There is a great variety among the forms already under cultivation and through hybridization with wild species, still greater variation may be induced.
This text is from: Luther Burbank: his methods and discoveries and their practical application. Volume 10 Chapter 7