Iris variegata hybrids with pallida

This is part 5. in a six part article on "Hybridization" for other parts click on number part 1; part 2; part 3; part 4; part 6

(Continued /from p, 332.) After these preliminary statements, which I trust the reader will excuse, on the plea that they clear the way for what is to follow, I may turn now to my own special attempts.

Hybrids of I. variegata with I. pallida.

I have in my garden an Iris which I received under the name of I. variegata. It is not a typical variegata, since it has not the full golden-yellow of the type, but in its duller colouring tends rather to I. sambucina or I. lurida. Still I feel compelled, on the whole, to call it variegata ; and it possesses one striking physiological character of variegata : it dies down completely and early in winter. This, as old Parkinson noted long ago, is a very distinct feature of I. variegata. Left to itself, this Iris has never seeded with me ; during some six or seven years I have never gathered a pod, or even seen an ovary really begin to swell unless I had manipulated the flower. In the summer of 1880 I removed from a plant all anthers as soon as the flowers opened, I may here remark that, with very few, and these doubtful, exceptions, all Irises are protandrous ; that is to say, the anthers burst before the stigma is ready to receive the pollen, the readiness of the stigma* being shown by its separating from the bases of the crests, and falling down into a horizontal or inclined position. With a very little care, all the anthers may be successively removed, even before they have burst, and certainly in time to prevent any pollen falling on the stigma. I think, therefore, that I may safely assume that the plant in question could not have fertilized itself. Upon the stigmas of some dozen or a score of flowers I placed, in due time, the pollen, in some cases of I. pallida {a fairly typical form), in others of the large oriental form of I. germanica, marking the flowers thus treated. Of the flowers so manipulated nine gave large thoroughly turgid pods, which on dehiscence were found to be full of well formed seed. Of the rest some swelled at first, but subsequently went off. Of the flowers on the plant not so manipulated not a single one so much as began to swell, and this was also true of the few last flowers, which did not open until the manipulated ones had withered and set, and from which, therefore, I did not think it necessary to remove the anthers. I concluded from these results that the pods in question were the products of the strange pollen which I had put on the flowers — that, in fact, I had effected hybridization; and I do not as yet see any flaw in the argument leading to this conclusion.

Unfortunately I did not affix any mark distinguishing those flowers on which I had placed germanica pollen from those on which I had placed pallida pollen. I have found, however, by experience that the pollen of pallida is very much more potent than that of germanica. Every hybridist is early struck with the fact that the pollen of some forms produces seed much more readily than does the pollen of other forms ; and this is true of Irises also. So far I have not as yet succeeded in getting any ripe germinable seed as the result of the application of germanica pollen, whereas I have in various stages successful products of pallida pollen (including several varieties of pallida) placed on very different flowers. And while in the summers of iSSi-83 I have again succeeded in impregnating I. variegata with pallida, all my attempts to cross variegata with germanica have absolutely failed. I conclude, therefore, that all my seed was probably the result of pallida pollen, and this conclusion is borne out by the characters of the seedlings. I shall, therefore, venture to speak of their parents as I. variegata and I. pallida.

The seed was gathered as soon as ripe, and sown immediately. It germinated very readily, and I have from it a very large number of seedlings, some of which flowered in the summer of 1882, and still more this summer, but a large number have yet to bloom. The special characters of the seedlings vary very considerably ; it would be tedious to enter into detail, but the following general statement may perhaps not be without interest.

In foliage they are for the most part intermediate between the mother and the father, but favouring the former rather than the latter, very few indeed showing the broad massive leaves of pallida. Some have red bases to the tufts of leaves, as had the parent variegata, others have green bases like pallida ; but nearly all the plants resemble pallida and differ from variegata in that the leaves do not die completely down in winter. In stature also the children are intermediate between their parents ; most, however, have the shorter scape and more compressed inflorescence of variegata, while some few show the taller more loosely branched stem of pallida.
Perhaps the more characteristic feature of I. pallida is the possession of thin papery colourless or white spathe valves, which become scarious so early as to lead one at first sight to fear that the as yet unopened bud is about to wither. In variegata the spathe valves are green flushed with purple, and much more persistent. In this respect also the majority of the seedlings were intermediate, having spathe valves which early became scarious, but yet turned brown flushed with purple, instead of taking on the silvery whiteness of the spathe valves of pallida.
The flowers themselves varied exceedingly in size, form, and colouring. In general the form of the flower and of its component parts, by the greater length of the perianth tube, by the narrower more pointed crests of the style, and by the shape of the segments, drew near to variegata ; and the blood of this, the mother, was in most cases obvious in the bold and conspicuous veining of the claws of both the falls and the standards. In point of colour I was able to arrange a long series, passing from nearly typical pallida, through a variety of tints, to something which was as nearly as possible a reproduction of the mother, variegata. There was, however, on the whole, a tendency, on the one hand, to the development of a deeper blue than is ever seen in pallida ; and, on the other, to the appearance, especially in the standards, of dusky and dirty hues of yellow.
Lastly, though I. variegata has no odour at all, many of the seedlings were exceedingly fragrant, more so even than I. pallida, the scent being as strong, and very much of the same character as that of I. plicata or I. Swerti.
I venture to think, then, that I have in this case not simply produced a number of variations from the type of the mother, but actually effected a hybridisation, the offspring favouring the mother in foliage and habit (save as far as relates to the greater or less persistence during winter), and in the form of the flowers, while the influence of the pollen is most evident in the large amount of blue coloration visible in by far the greater number of the blooms.

I stated a little way back that I believed that a large number of the Irises which nurserymen speak of as varieties of germanica 'are hybrids ; and among these hybrids of which I am speaking are many which seem almost identical with various " named " forms of our gardens. Very many of these named forms ate by Mr. Barr classed as varieties of I. neglecta, to my mind very justly so. Now it is specially these so-called forms of neglecta to which my hybrids come near ; so much so that I feel very much inclined to believe that the typical and original neglecta of Hornemann is actually a hybrid between I. variegata and I. pallida.
But I may perhaps go farther than this. Very many of the garden varieties may be classed as forms of I. squalens, I. lurida, I. sambucina (which are veritable species found wild in Europe), but some of my hybrids run very close indeed to these. These three Irises have many points in common and have been at times variously confused by successive authors (indeed I cannot say that my own mind is as yet clear about them) ; they are also related to variegata, the four forming a group, the members of whioh are more closely connected with each other than with any other Iris. The view which naturally commends itself is that these four forms have arisen from one of the four, or from some lost common ancestor, by simple variation without the admixture of foreign blood. But my hybrids raise the suspicion that possibly natural hybridisation may have intervened. Of course further evidence is needed before a definite opinion can be arrived at. In this relation I may, perhaps, state that in the summer of 1S81 I crossed the same plant of I. variegata with the pollen of a handsome garden Iris known as Queen of the May, and have obtained a large number of seedlings. Of these I may have to speak hereafter, meanwhile I quote them, since among them are plants the flowers of which, save as regards some inner structural features which a casual observer would overlook, are almost exactly like I. flavescens. Now the Queen of the May, though having reddish flowers, is in all essential characters a pallida, almost a typical pallida.
Whether it be, as I suspect, a hybrid or simply a variation I do not know ; but unless it be a hybrid with, what seems extremely unlikely, flavescens blood in it, so that the appearance of a plant like flavescens in my seedlings is simply a reversion to a part of the ancestral blood, the fact of the appearance of the flavescens features in the progeny of variegata (from which flavescens is widely different) as the result of hybridisation suggests that the wild flavescens is itself a hybrid.
To conclude this long story, I will call to mind a suggestion of Dean Herbert. That wonderfully sagacious man (and the more I try to follow up his work the more I marvel at his breadth of view and at his insight) threw out the suggestion that all the bearded Irises growing round the Mediterranean basin were after all mere varieties of one form, and would be found to cross readily with each other. My own short experience leads me to believe that, within limits determined more by breeding capacity than by specific differences, he was right ; and this opens up the question whether the variations giving rise to our many species of bearded Iris are, in part at least, due to natural hybridisation. M. Foster.
{To be continued. see part 6

• By the stigma I mean the stigmatic surface only, the little ledge below the crests. Most authors give the name stigma to the whole tripartite upper part of the style, and speak of the crests of the stigma ; but it seems to me more appropriate to speak of the style as dividing into three parts, each beaiing two crests, and below these a stigma ; for the stigmatic surface is not in the Iris as., e.g., in Gladiolus, extended over the whole of the tripartite end of the style.
To view original in the Biodiversity Heritage Library click here; "Notes on Irises", The Gardeners' Chronicle September 22, p. 373.
[September 22, 1883.mation

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