Horticulture, 3: 97-102 (1837)
Charles Mason Hovey
Art. V. On
the Production of new varieties of Flowers, from Seed, by Cross Fertilization.
By the Conductor.
The immense number of new flowers, as well as fruits, which have, within late years, been raised by the English and French horticulturists, has been the means of enriching our gardens with artificial productions, in many instances, far more splendid than the original species. At first this operation was confined to a very few genera of plants, but within the few past years almost every flower commonly grown in our gardens, or at least in the gardens of our transatlantic friends, has been subjected to the skill of the florist. It is almost unnecessary to mention any particular plant, so familiar are these artificial productions to every gardener; the rose, the camellia, and particularly the dahlia, have been more the immediate objects of their care, and the gorgeousness of the blossoms of some, and the delicacy of others, of the latter plant, have commanded, and indeed have well deserved, the highest admiration of every amateur and lover of flowers. There seems to be, and there probably is, no limit to the production of new varieties.
It is not our object in the present paper to go into a physiological discussion of the nature of these, generally termed, hybrid productions, but which some writers seem not to consider as such; but merely to make some remarks which may be a guide to the novice in the raising of new varieties.
There is no department of horticulture or floriculture which affords more pleasure, or engages so much the interest of the cultivator, as the production of new varieties of fruits or flowers. To commit the seed to the earth, watch its vegetation— its progress in its infant state—its more mature growth—guarding it from all dangers,—-and, finally, as it begins to show signs of perfecting its fruit or opening its blossoms, to mark its daily progress, until it greets the eye of the impatient cultivator, either affording him pleasure or disappointment in its qualities or properties, is a source of intense gratification.
To produce a new and superior variety of any fruit or flower is an achievement of no mean importance; and the producer of such is entitled to the gratitude of every lover of floriculture.
To see at once the importance which the production of new varieties, by impregnation, has had upon the progress of floriculture, we need but point out the dahlia. Some years ago (not at the most above ten or twelve) there was nothing but single ones, or very inferior semi-double ones, known in this country. Look, however, at the variety now cultivated. Thousands of kinds of almost every shade of color (exeept blue or any thing very near approaching it, and which will not probably be ever obtained,) and with several shades in one individual flower. Until hybridization was introduced, none other than self-colored ones were known—that is, flowers of which the petals were all of one shade; but now we have shaded, striped and edged ones of surpassing beauty and shape. The camellia is another instance;—until 1819 no seedling varieties had ever been obtained except in China. From the common warratah, however, by impregnating that sort with the finer double ones, several kinds, almost equaling in splendor the Chinese ones, have been successively raised. Not above eight or ten varieties have since the above date been introduced from China; yet some collections in France and Germany enumerate three or four hundred sorts. In this country, in New York, several varieties have been produced, one or two of which equal, if not excel, any of the English seedlings. Of the more tender flowers, the geranium, the calceolaria, and the amaryllis have been subjected to the skill of the florist; of hardy or nearly hardy kinds, the rhododendron and the azalea have been wonderfully improved; and here we have evidence of the great importance of cross fertilization in that most superb variety, the alta clerense. This plant was raised from the R. arboreum of Nepaul, a quite tender species, which had been impregnated with a hybrid between the catawbiense and ponticum; and the history of its production is here worthy of note. To obtain a hybrid between the R. arboreum and some of the hardy kinds had long been desired; but the specimens of the arboreum at Highclere (the Earl of Caernarvons,) had never shown any disposition to bloom. It had, however, flowered at the Grange and some other places, and from the former an umbel of its splendid blossoms was produced, and carried in a tin case to Highclere. With the pollen of the flowers the seedling before named was impregnated, and about eighteen hundred seedlings were raised. These were distributed among several nurserymen before they flowered; but among those retained at Highclere was produced the alta clerense.
The Hon. and Rev. Wm. Herbert, a well known raiser of hybrids, has produced a great number of new varieties of different genera; and his experiments go to prove that these varieties are in many instances fertile, and will reproduce, with impregnation, other new varieties. His experiments have been mostly made with the Amaryllidaceae and the Gladioli, though he has extended them in a greater or less degree to most all classes of plants. The hybrids he has raised of the Gladioli are, many of them, extremely splendid.
In the production of new varieties, the first object of the cultivator should be to select such plants as would appear most likely to produce fine kinds from the intermixture of the two; thus in the camellia the semi-double red, sometimes so called, the rosea or Middlemist's of most catalogues, impregnated with the single white, produced the three splendid varieties known as Press's eclipse, punctata, and rosa mundi, all of which were raised from one capsule of seed. Here we see in these kinds a resemblance to both parents in the foliage. They are each handsomely shaped, but the flowers of eclipsis are better formed than either of the others. The warratah, or anemoneflora, is the parent of a major part of the new varieties; but, in general, the seedlings raised from this are not near so perfectly formed flowers as those raised from the rosea. They most always partake too much of the character of the female parent, and have one or more rows of outer petals, and the centre of the flower filled with small ones, frequently intermixed with stamina. There are, however, some exceptions, as we may instance eximia, which was raised from the warratah, as it is in shape very similar to the double white. It should be remarked, in raising new varieties of camellias, that it is desirable that they should approach as near as possible to the form of the double white— that generally being considered as a standard, as regards form. We know of but one, in addition to the eximia, of all the European or American seedlings, which has this form, and that is the celebrated Floyii, which, in our opinion, far excels all the colored varieties. Of this latter kind, we know not its parentage. As this tribe is now attracting the attention of florists, we hope that those who are raising seedlings will not let this thought escape their notice, as it is better to have a few, and have them splendid, than a large number possessing little or no beauty.
The geranium has long been noted for its superb varieties, and at one time, in England, the new sorts were in great demand, and brought an exorbitant price. The Geraniaceae of Mr. Sweet spread a taste for this tribe, which brought it into very extensive cultivation, and no collection was complete without the new geraniums. But the publication of this work was suspended, and the taste for the plants gradually lessened until they were unfashionable; this was, of course, a sufficient cause to abandon their growth, however so beautiful they might be; and although they are at the present moment again becoming more generally cultivated, yet they will not ever in England be so highly appreciated as they were once. In this country the taste for them is on the increase, and we shall probably soon see many superb collections. But the varieties are of English or French origin, and as yet few attempts have been made to produce new sorts here; we cannot account for the apparent neglect of experiments in the raising of seedlings, unless it is that the plants are not yet sufficiently in demand. We hope, however, that our amateurs will soon boast of their seedling geraniums, as well as of camellias and other flowers. One advantage the geranium possesses over the camellia is, that while the cultivator has to wait for the result of his experiments, in the latter plant, five or six years, the former may be known in eighteen months, and oftentimes less. Of the English growers, Messrs. Dennis & Co. are the most celebrated.
But the dahlia has received, in a short space of time, at the hands of the florist, more attention than any other flower. Requiring but little patience to produce new sorts, they have been grown in immense quantities both by the amateur and the nurseryman, and the consequence has been the production of a great number of magnificent varieties. As an instance, however, of the chance of obtaining a fine sort, only six have been saved, worthy of naming, out of seven thousand seedlings. Cross fertilization is not so necessary with the dahlia as with most other plants, as the blossoms are produced in the open air in great abundance, and the- wind and bees effect what, in other plants, could only be done by the hand of the cultivator. The first parti-colored ones were produced by impregnation, and where it is attended to, and the flowers covered with gauze, to protect them from the bees, the chance of success is much greater.
These are but a few of the plants which have been so wonderfully improved by artificial productions, and are merely mentioned to show to what extent cross fertilization has been, and still may be, carried. When we reflect that, but a few years since, collections of plants were almost confined to species alone, with but few varieties, and these accidentally obtained, the importance of continued experiments with almost any family must be apparent. But unless these experiments are carried on judiciously, the new varieties will be less beautiful and desirable.
But one great value of fertilization is the effect it will have upon the naturalization to our climate of many, what are now termed, tender plants; and not only will naturalization be affected, but the beauty of the plants will generally be greater, as we have seen in the Rhododendron alta clerense, and, for a perhaps more familiar example, the hybrid roses, which partake of the beautiful character and habit of the Chinese, and are yet sufficiently hardy to stand our winters unprotected.
It is to the .Rhododendron, with which botanists have now united the Azalea, that we would direct the attention of cultivators. We have but two species, the maximum and album, of this family, which are hardy in our climate. But by fertilizing the blossoms of these with the magnificent arboreum of Nepaul, or any of its varieties, or with any of the oriental azaleas, we shall, in all probability, raise intermediate kinds, which will possess part of the beauty of the male parents, and still be sufficiently hardy to stand our winters unprotected, From the Azalea nudiflora, heretofore so called, has already been raised many very superior varieties: our common viscosa may, no doubt, be made to produce very handsome varieties: calendulacea, common in the middle and southern states, is the parent of a very large number of seedlings of great brilliancy. This tribe is sadly neglected by our amateurs and gardeners, and it is rare even to find the most common species in our gardens; but we hope more attention will be given to them, and that we shall see them in shrubberies and pleasure-grounds, where they certainly, in the months of May and June, eclipse all other shrubs. In England, France and Germany, several hundred new kinds have been raised. The tree paeony is another plant from which new varieties may be raised, and, as they are hardy, would be valuable ornaments to the shrubbery. The plants flower in about five or six years from the time the seed is sown.
The operation of impregnation is simple, and easily performed: the only thing necessary to know is, the proper time at which the stigma is ready to receive the pollen. This varies in different plants: thus in the camellia the stigma should be impregnated almost as soon as it is seen, even before the flower fully opens: but in the geranium it should not be performed until some time after the flowers expand: one reason why geraniums do not generally impregnate themselves is, that their anthers fall before the stigma is ready to receive the pollen. In flowers that are likely to be impregnated with their own pollen, the anthers should be cut out carefully with a small pair of scissors, so as not to injure the stigma, before they burst, otherwise the stigma will be fertilized by its own pollen: if the plant to be impregnated stands in the open air, it will be necessary to cover it with gauze, to keep the bees from conveying to the flower particles of pollen from other flowers: if in the green-house or stove, unless late in the season, there will be no necessity of this. Fertilization may sometimes be effected with two or three different kinds, as it is supposed that the fecundating dust will fertilize another portion of the seeds in the capsule than those at first impregnated. Mr. Knight has stated that he dusted the stigma of a smooth cabbage with the pollen of a Savoy and of a red cabbage, and obtained seedlings which were both curled and of a red color. This shows that a plant may be impregnated, and with effect, with two, and perhaps more, different sorts. We have ourselves applied the pollen of two different camellias to one stigma, but we cannot for some time tell the result. The same experiment we tried with some seedling strawberries: but the labels were unfortunately lost, and, consequently, we could form no correct opinion. From the experiment of Mr. Knight and others, and also from the fact that the stigma is composed of minute tubes, through which the fecundating dust descends to the germen, we have no doubt but that the stigma of a flower may be impregnated with two or more kinds, and that the seedlings will partake more or less of the varieties from which the dust was taken.
|*CybeRose note: Presumably Harison, who also raised the rose, 'Harison's Yellow'.|
Hitherto in this country very few individuals have attempted to produce new varieties by impregnation, and these attempts have been confined to a very few classes of plants. The practice may therefore be considered as yet but in its very infancy with American cultivators. Mr. Floy, nurseryman, of New York, and Mr. Harrison*, have probably done more than any others; but their efforts have been chiefly confined to the camellia: indeed, if we except these individuals, we know not of any other attempts to produce new varieties, worthy of note, the results of the experiments of which have yet been made known to the public. Within two or three years many seedlings of camellias, amaryllises, and of various plants, have been raised, but few of them have yet attained to a flowering state; we may anticipate soon, however, a display of new varieties obtained in this manner.
It is with a view to call the attention of amateurs and cultivators of plants to the importance of raising new varieties, by cross fertilization, that we have at this time thrown out these few desultory remarks. Many species and varieties of various plants are now coming into bloom, and more particularly the rhododendrons and azaleas, and the present spring should not be suffered to pass by without saving a few seeds. Many cultivators never make a beginning, for to look forward four or five, or more, years seems too long a space to wait to see the result of their labors. We would say to those who adopt this opinion, make a commencement, sow every year, and after those of the first planting begin to bloom, a succession will constantly follow, affording, in the anxiety to see the blossoms, and the continued display of new forms and colors, a varied and constant source of pleasure and gratification.