Foster on Balkana and Cengialti Hybrids
This is part 6. in a six part article on "Hybridization" for other parts click on number part 1
; part 2
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; part 5
NOTES ON IRISES. (Concluded from p. 374. Gardeners' Chronicle 1883)
Hybrids of I. balkana
with I. cengialti
In support of Dean Herbert's view, I may call attention to a hybridisation which I think I have carried out between two Irises much further apart from each other than the two discussed above.
I. balkana is a dwarf Iris from the Balkan mountains, introduced and named by Janka. It belongs to the pumila group ; the short scape bears one, rarely two, somewhat large and handsome purplish-brown flowers marked with very bold veins.
I. cengialti is a curious Iris from Mount Cengialto in the Tyrol. It may briefly be described as a very dwarf pallida, with a branching scape hardly more than a foot high, and small pleasing sky-blue flowers. In general aspect at first sight it seems an absolutely different plant from I. pallida, and yet when you come to examine into its special features, it becomes very difficult to establish any satisfactory difference, and Mr. Baker regards it as a mere variety of I. pallida.
I may here remark that there exists a series of low-growing Irises, almost exactly the dwarf reproductions of the commoner taller species. Just as this X. cengialti may be regarded as a dwarf I. pallida, so also is there a dwarf I. variegata, a dwarf I. neglecta, a dwarf I. amcena, and probably others. Whatever be the view taken of the exact nature of this I. cengialti, whether it be regarded as a definite species or a mere variety of I. pallida, it undoubtedly belongs to the division of Irises with a branching scape, and thus differs widely from I. balkana, with its one, or at most two, flowers on a stem.
In the spring of 18S0 I placed the pollen of I. cengialti on the stigmas of a flower of I. balkana, the anthers of which I had previously removed, with the result that the ovary began to swell. I have not had sufficient experience with I. balkana to know if it seeds freely ; but I have seen enough of I cengialti to be aware that its pollen, like that of I. pallida, has considerable potency. I took care that no pollen either of the same or of any other flower of I. balkana touched the stigma of the flower operated on. If the swelling of the ovary was not due to the cengialti- pollen it must have been due (parthenogenesis being excluded) to pollen of some other Iris brought by insects. This, as I have already urged, is unlikely ; and the sequel, I think, shows that in this case also a cross was really effected.
While the pod thus fertilized, though well swollen, was still green and unripe, my gardener snicked the scape with his scythe, and soon after a friend broke the pod off altogether. Hardly hoping to be successful, I placed the pod in the greenhouse, with the broken end of the scape plunged in damp cocoa-fibre refuse. Happily the pod ripened and gave me seventeen fairly good seeds, which were sown at once. In the spring of 1881 two seeds germinated, but the seedlings soon damped off. In 18S2 fifteen seedlings appeared and flourished ; of these fourteen flowered this spring and summer, the remaining .one being sickly.
In foliage these seedlings differ a good deal from each other, but, on the whole, are intermediate between the two parents. The leaves of I. cengialti are short, comparatively broad, straight, and yellowish-green ; those of I. balkana are narrow, very pointed, markedly curved, and falcate, and their green has a more decided mixture of blue. The leaves of the seedlings are in some plants straight, in some falcate, in most cases broader than I. balkana, but narrower than I. cengialti ; and though the greater number are of a yellowish-green colour, some are more distinctly blue-green than is I. cengialti.
As regards the inflorescence and flowers, since, as I believe, a real hybridization was effected, perhaps I may be allowed to speak in detail, on account of the interest naturally attaching to the characters of hybrids as compared with those of their parents.
Whereas I. balkana bears a single terminal flower, very rarely two (so Janka), in eleven of the seedlings, besides the terminal flower, a lateral flower, on a short peduncle, sprang from a spathaceous bract about half way up the scape. In two plants (Nos. 4 and 9) there were two such lateral flowers, each pedunculated, and each springing from its own bract. In one plant (No. 10) each stem (and there were several on the same plant) was regularly branched, after the fashion of I. cengialti, and bore in all five flowers ; in fact the plant was, for an Iris, extremely floriferous.
As regards colour, three plants only (Nos. 2, 3, 12) were blue or purple, the colour being not exactly like either parent, the conspicuous brown veining of I. balkana being absent, while the light sky-blue of I. cengialti was not taken on. In texture the segments were rather delicate, like those of I. cengialti, and not stout and firm like I. balkana. In one case (No. 10) the flowers were small, of a pleasing creamy-yellow, with a very bright orange beard. In one case (No. 8) the flowers were large and white, the lamina of the falls and standards being largely spotted and streaked with purple. In the remaining nine plants the flowers were white, with a somewhat conspicuous blue or purple veining, which gave the petals a sort of slatey hue, the colour of the beard varying from bright orange to dull yellow.
It may seem surprising that eleven out of the fourteen plants should be entirely, or almost entirely free from the blue colour which is so conspicuous a feature of both supposed parents. Nor would I venture to insist on this being a token of hybridization having been effected, since for all I know natural seedlings of I. balkana might sport white or yellow as do seedlings of I. chamreiris, I. olbiensis
, etc; but I do venture to insist on the beards of the seedlings as affording direct proof of mixed blood. The beard of I. balkana is white and blue, while that of I. cengialti (and in this it shows its pallida affinities) is orange. I take it that the possession by these white-flowered seedlings of an orange or yellow beard clearly shows the influence of the cengialti pollen.
One marked feature of I. balkana may be noted in the somewhat inflated, pointed and markedly keeled persistent spathe valves, while I. cengialti betrays most distinctly its pallida affinities in its delicate spathe valves early becoming scarious and silvery white. Now, of these seedlings the spathe valves were, in one case, most distinctly scarious like I. cengialti, in four cases somewhat scarious, and in six slightly scarious, that in three cases only could they be spoken of as thoroughly persistent like those of the parent I. balkana.
Taking these facts, and others with which I need not weary the reader, into consideration, there is I think ample evidence that I have really crossed the two above mentioned forms, that is to say that I have brought into union a member of the pumila group and a member of the pallida group — two groups of Iris separated by a long interval from^each other ; and have thus made a step towards verifying the speculations of Dean Herbert.
I may add that these hybrids are not sterile. It is true that they have not spontaneously produced seed, but I have attempted to fertilize them with another (and very different) Iris, and have obtained several pods with some apparently good well-formed seed. Of these, if I live and all goes well, I may have something to say in some future year.
5. On a Proliferous Iris. — As far as my experience and knowledge goes the following occurrence in an Iris is new and worth recording. The first of the hybrids between I. balkana and I. cengialti just described was grown in a pot and wintered in a greenhouse. It accordingly flowered early, and some time in May or June a second scape with a terminal flower and a lateral bract appeared. I cut off the terminal flower, and some time after was surprised to find that though no second flower appeared at the lateral bract the scape did not wither, but remained green. Early in August I noticed that the bract appeared swollen at its base, and, moreover, was splitting. On examination I found that the bud in the axil of the bract, instead of growing up into a flower, had become transformed into a bulb, and had already formed a tiny rhizome, from which a commencing root was already pushing. I cut off the stem below the node and planted it in a pot, so that the tiny root had access to the soil. So far it seems doing very well, and I shall watch its growth into a plant with great interest.
The formation of bulbs in the axils of the leaves and branches of branching bulbous Iridaceous plants, such as Freesia, Sparaxis, &c., is very common. [We have seen the same thing at Marica. Ed.] None of the bulbous Irises (Xiphion) have branching stems, or perhaps we might see a similar occurrence in them. Its repetition in a rhizomatous Iris is rather curious, and I perhaps may claim this physiological freak as an additional proof of these seedlings being real hybrids. M. Foster
, Shelford, Aug., 1883.
To view original in Biodiversity Heritage Library click here "Notes on Irises", The Gardeners' Chronicle September 29, p. 406.
You may also find this additional article interesting Sir Michael Foster's 1885 article on "So-called German Irises"
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