The Garden 8(106): 148-149 (Aug 21, 1875)
RAISING NEW PELARGONIUMS
PELARGONIUMS form an extensive family, which is of considerable importance from a decorative point of view. It is divided into several sections, among the most conspicuous or important of which are those known as the "zonal," the "show," and the "fancy" varieties, It is generally admitted, however, that these terms do not satisfactorily designate the class of plants to which they are respectively applied. And yet there appears to be some difficulty in assigning other and more comprehensive terms which would be likely to be recognised and adopted. The zonal varieties are supposed to be descended from two or more of the Cape species, viz., P. zonale, P. inquinans, and P. Fothergillii; while the show and the fancy sorts are probably derived from P. grandiflorum, P. cuculatum, or other large-flowered species. Considerable uncertainty, however, exists as to the origin of these plants. The practice, still continued, of applying the term Geranium to this genus is somewhat inexplicable, as, putting botanical distinctions aside, the general appearance of the two classes of plants is essentially distinct. The Pelargoniums are nearly, if not all, tender, being mostly natives of the Cape of Good Hope; while most, if not all of the Geraniums are indigenous to Europe, some of them even natives of Britain, and, consequently, hardy. Not less inexplicable is the notion entertained by some that the name Pelargonium should be applied to the zonal section, and that of Geranium to the other sections, known as the "show," the "fancy," and the "sweet-scented" varieties. It is true that the numerous varieties forming the zonal section differ very materially from what are called the "show" and "fancy" sorts. But even the structural resemblance which these sections bear to each other is certainly much greater than any of them bear to the Geranium properly so called, such as G. pratense, G. platypetalum, &c.; and this circumstance alone might be supposed to be sufficient reason for applying the name of Pelargoniums to all sections, if it is applied to any of them. The term zonal is sometimes objected to, when applied to plants whose leaves show no indication of a zone; but the zoneless varieties may, I think, continue to be considered zonals—as, in all other respects, they agree with them,—until some more applicable and comprehensive term can be applied to the zonal, as well as to the various other sections of this genus. Cross-bred and hybrid are often thought to be synonymous terms, and are frequently applied indiscriminately. This, however, I am inclined to think, should not be the case. Nature appears to favour or promote the production of crossbred varieties, inasmuch as every hermaphrodite flower generally possesses male and female organs, and yet the stigmas of such flowers are rarely fertilised by their own pollen, as, in most cases, this is ripe and dispersed before the stigma of such bloom is in a sufficiently forward condition to be fertilised by it; while, in other species, the stigma is frequently fertilised by foreign pollen before its own is ripe. As an instance of the way in which flowers in general are fertilised by other pollen than their own, I may mention the case of a bloom of a double Zinnia, of somewhat extraordinary dimensions and of peculiar colour, which was produced in a bed among many other double-flowered Zinnias of various shades of colour. The plant which produced the bloom to which I am alluding had all its other flower-buds removed before they expanded, and this single bloom was allowed to mature its seed which was carefully sown this spring, and the plants produced by it (some three dozen or more) were planted in a bed, and are now in flower, producing blooms of all shades of colour, including white, yellow-bronze, purple, &c., but no plant among them has flowers of the same shade as that of the bloom which produced the seed from which they were raised. Therefore, as has already been said, Nature, by insect agency or otherwise, but without the intervention of man, facilitates the production of cross-bred varieties, while, on the other hand, she discourages hybridity, however accomplished, by invariably placing such productions under the ban of sterility. Zonal Pelargoniums, now more believed under consideration, are, with good reason, believed to be descended from two or more species, say, zonale and inquinans, and, in this instance, sterility has not been induced. A variety, which has recently originated in a garden at Nice, and which M. Jean Sisley, of Lyons, considers to be a hybrid between a zonal and some Ivy-leaved species, produces, nevertheless, fertile seeds; it is, therefore, quite possible that some plants which, according to botanical arrangements, have been separated and considered to be distinct species, may, nevertheless, be more properly regarded as mere varieties. All the plants, however, which I have raised between the modern zonal varieties and Pelargonium peltatum, have invariably proved sterile; nor have I ever succeeded in inducing the hybrid plants, raised by Mr. Wills, to produce seed. These, by the bye, I am very much inclined to think, have also been produced between P. peltatum and some of the zonal sorts; and, if this be so, no hybrids, as far as I know, have, up to the present, been obtained between P. lateripes and the zonals; for, according to London's "Hortus Britannicus," the former kind and P. peltatum are considered to be distinct species. If therefore, very considerable difficulty is experienced in obtaining a cross between allied plants of kindred species, it may well be supposed that this difficulty will be greatly intensified when attempts are made to produce hybrid plants between distinct genera; yet this, Mr. Lowe, of Highfield House, near Nottingham, considers he has accomplished. He has, he thinks, produced a variety between Madame Vaucher, a white-flowered zonal, and the hardy blue-flowered British plant, Geranium pratense. This may, of course, be so; indeed, Mr. Pearson—an authority, as may be supposed, on such matters—admits himself to be nearly, if not altogether, convinced that such is the case. All attempts, however, made by me in that direction have hitherto failed. During the early part of the present season I potted several plants of G. pratense, G. platypetalum, and G. anemonifolium, and placed them in situations in which it was hardly possible that kindred pollen of any kind could reach them, otherwise than by my own hand. The blooms were duly emasculated, and zonal pollen carefully applied; and, in due time, what appeared to be seeds were freely produced. But these, on close examination, were found to be merely empty seed vessels. They were, however, sown, in order that no chance should be thrown away; but, as was expected, no plants were the result. This experiment was also reversed—that is, Geranium pollen was used for fecundating blooms of the zonal Pelargoniums, the result of which has yet to be ascertained; but sanguine hopes are not entertained of its success.
Dr. Denny, of Stoke Newington, a successful raiser of improved zonal Pelargoniums, attaches much importance to the influence or potency of the pollen parent in producing the desired qualities in colour, form of flower, habit, constitution, &c., of the progeny. But, in order to ensure this prepotency of the pollen plant, be thinks it necessary to use the pollen somewhat lavishly; in fact, to saturate or smother the stigma of the intended seed-bearing plant with pollen grains. My own experience in the matter has not led me to observe the superior influence of the pollen parent, and I should think one parent as likely to be prepotent as the other; or, if anything, I would rather be inclined to say that, as regards constitution, the seed-bearing plant has most power. My experiments, however, have generally been directed more towards the production of certain qualities in foliage than in flower, and whenever variegated plants have been allowed to become the seed bearers the progeny has generally been found to be weak or delicate in constitution, although the pollen used may have been furnished by the strongest-growing green-leaved varieties. I may state, too, that I never succeeded in raising a robust or free-growing tricolor Pelargonium from seed which had been produced by a variegated plant. On the contrary, I have always found that in cases where the seed-bearing plant was variegated, and the pollen plant green-leaved, there was a greater percentage of variegated seedlings among the progeny than in cases in which this order was reversed, that is, the seed-plant green-leaved, and the pollen plant variegated, and the latter will always be found to furnish the strongest and finest varieties. If a union is effected between two varieties of corresponding vigour of constitution, the transmission of qualities from each parent will generally be found to be pretty much the same. Some years ago I fertilised a few blooms of the well-known white-flowered zonal Madame Vaucher, with pollen taken from a strong-growing variety with a well-defined zone, and large trusses of dark scarlet flowers, named Emperor of the French; from the result of this union was selected a variety which has been long known as a good bedding sort viz., Culford Rose—a strong vigorous variety, with large trusses of rose or cerise-coloured flowers. In this instance it will be observed that the pollen parent was prepotent in the matter of colour, but it must also be remembered that in this batch of seedlings there were also plants with lighter-coloured flowers, as well as some of darker shades. But, in no instance was a plant produced having blooms of as dark a scarlet as the pollen parent, nor so light-coloured as that of the seed parent. During the following season pollen from this Culford Rose was applied again to Madame Vaucher, and one of the results was a very dark zoned variety, with well-formed pink flowers, which was named Culford Pink; this proved to be an excellent bedding sort, with possibly the darkest zone of any zonal Pelargonium. About this time a series of papers on bedding Pelargoniums appeared in the "Gardeners' Magazine." In one of these it was stated that a good pink-flowered variety, with very darkly-zoned foliage, was something very much to be desired; and it was facetiously added, that whoever would furnish such a desideratum would deserve well of his country, or words to that effect. This variety, in all respects, fulfilled the conditions asked for. Pollen of it was also applied to Madame Vaucher, and the result was a batch of very light pink-flowered plants. The experiment was still farther carried out, and it was found that in about the fifth or sixth generation plants with flowers nearly, if not altogether, as white as those of Madame Vaucher, were produced.
From what I saw of Mr. Lowe's so-called hybrid variety I felt inclined to think that, like the French variety alluded to by M. Jean Sisley, it would produce seed pretty freely, and, if this be so, it by no means indicates hybrid origin. About the middle of last September I repeated an experiment which I had previously tried, with the view of ascertaining whether or not superfetation could be induced in the case of the Pelargonium, and, if so, it might of course be inferred that the same might take place amongst other hermaphrodite plants; or, at all events to ascertain for the second time whether or not the application of foreign pollen to the stigmas would have any perceptible effect upon the progeny in cases in which such stigmas had been previously fertilised by their own pollen; accordingly two plants of Pelargonium peltatum were again selected and placed in a structure where it was hardly possible that pollen from kindred species could by any means reach them, and, as soon as the stigmas were found to be in proper condition, a few blooms upon each plant were fertilised with their own pollen, and all other blooms were removed. On the following day the stigmas of one of the plants were covered with pollen taken from a zonal variety. The blooms upon the other plant were left untouched after the application of their own pollen. Both plants duly ripened seed, and the produce of each was sown in a separate pot, and germinated simultaneously; but, as was expected, the produce of the plant whose blooms had the second application of pollen were exceedingly diversified in aspect, although they all appeared to be of the peltatum type, the leaves of some of them were large, others exceedingly small; some had zoned foliage, the leaves of others were quite zoneless; while the plants raised from the seeds produced by the blooms which had received only one application of pollen were quite uniform in appearance. All the plants, however, were kept growing slowly throughout the winter months, and were planted in the open air about the end of May. All the seedlings raised from the plant whose blooms received only one application of pollen have now flowered, and their blossoms differ in no respect from those of the parent plant; while, as regards the produce of the twice fertilised plant, none of the seedlings have yet flowered, and—what is more remarkable—the plants are rapidly losing that diversity of appearance which distinguished them during the earlier stages of their development, although they are still very distinct from each other, and the appearance of flowers is looked forward to with interest. Should they approximate to the zonal type, this circumstance may perhaps be considered as favourable to the theory of superfetation; while, should the flowers be in no degree different from those of P. peltatum, it will be difficult to account for the diversity of appearance among the seedlings apparently occasioned by the second application of pollen, otherwise than by supposing that, even after fertilisation has been effected, the ovules may still, to some extent, be nourished or fed by the application of pollen to the stigma.