1911, Iris Unguicularis by Dykes

Gardeners' Chronicle p.251, April 22, 1911

NOTES ON IRISES.

I. UNGUICULARIS.

The worst feature of this Iris is its name, and it is indeed unfortunate that Desfontaine's name I. stylosa is thirteen years junior to Poiret's uncouth appellation, and cannot, therefore, properly be used. Moreover, the name stylosa is eminently suited to the plant, for it is one of the very few Irises in which the style rises undivided for some distance above the top of the perianth tube before branching into three.

However, I. unguicularis has many redeeming features, except, perhaps, in the eyes of those who garden in a cold, wet clay, and have not a warm, sunny corner against a house, where the addition of plenty of old mortar rubble to the clay would probably make the Iris quite happy. When it does well, it rewards us liberally for care in planting, for it is a joy to watch its buds unfold and open indoors in the warmth on a cold winter's day; and a large, well-established clump is quite capable of producing a hundred flowers at intervals between November and April.

One of the most curious features of this Iris is that, as a rule, scarcely any stem develops, and the flowers are only thrown up on a long perianth tube, 6 or more inches in length. The consequence of this formation is that the ovary is well protected from all but the severest frosts in its shelter at the base of the leaves ; indeed, in old-established clumps numbers of decaying capsules of seed may often be found deep down among the growths.

The species was first described as an Algerian plant, and many years later a Greek form was named I. cretensis by Janka. In his description he was so intent on pointing out the distinctions between I. cretensis and I. humilis M.B., which. indeed, are many and fairly obvious, that he quite forgot to tell us how to distinguish it from I. unguicularis. It has been said that the spathes are more scarious, and that the segments taper more gradually, but neither of these characters seems to be reliable. The only difference is in size, and whether this is inherited or due to environment has not yet been proved. So far, I have not been able to get seed of the Greek forms, though, with less arctic weather than that which April has so far brought us, I am not without hope of doing so this year, for there is abundant promise of flowers still to come.

The form that usually goes by the name of I. cretensis has narrow leaves that grow in upright tufts, after the manner of the ordinary I. unguicularis. I have, however, a form from the island of Cephalonia, which produces flat, fan like spreading growths, and this throws its flowers well above the leaves. Its colour is a dark-reddish lilac, and its flowers are never produced before April. Another form, which I believe comes from Asia Minor, and which I obtained under the name of I. agrostifolia (the name has apparently no authority) has extremely narrow, upright leaves, narrower. I think, than those of any other Iris. It is not very floriferous, but does not differ widely in flower from the Cephalonian form.

Sixteen years ago, Albow, in his Prodromus Florae Colchicae, p. 232. described as a new species I. lazica. which is said to differ from I. unguicularis by the much shorter tube and distichous leaves. Its name is derived from the locality in which it grows, namely Lazistan, the region along the south shore of the Black Sea beyond Treoizond, at the extreme eastern limit of the Turkish dominions. This plant has recentlv been introduced into cultivation by Mr. C. G. Van Tubergen, Junr., of Haarlem, who has very kindly sent me flowers. It was shown, I believe, for the first time at the Haarlem Jubilee Exhibition last spring. A plant growing here has very broad leaves, and the fan-like habit of the Cephalonian plants. No flowers have yet appeared, though I think that buds are pushing up. The flowers that I have received are of a dark-reddish lilac on the blade of the falls, the hafts of which are veined with same colour on a white ground. The central yellow line is present, as in all the forms of I. unguicularis; the style rises likewise in a column for some distance, and, moreover, the one feature which is peculiar to I. unguicularis is also present in this form, namely the beautiful appearance as of gold dust on the back of the style branches. This phenomenon is produced by a number of transparent, whitish, conical projections, each of which is topped by a similar sphere. The golden colour is produced by a mass of brilliantly-coloured grains, which varies in position from the centre of the sphere to any part of the supporting cone. Both cones and spheres are very fragile, and appear to be filled with a colourless liquid. They present a beautiful sight under the microscope, and occur, as far I know, in no other species of Iris. I. lazica also agrees with all the other forms of I. unguicularis in that the apex of the filament is adherent to, but not coherent with, the style column.

The really distinct feature in I. lazica is the presence of a stem of about 3 inches in length which is triangular in section and equal in length to the perianth tube, which is thus much shorter than the usual length in I. unguicularis. Curiously enough, the Botanical Magazine figure of I. unguicularis, tab. 5773, represents a stem about as long as the tube. No mention is made in the text of this feature, and it may be that it does not occur in plants from Algiers. Seedlings of the ordinary garden form, which are now flowering here, vary considerably in the length of the tube, the shade of colour in the flower, in the shape of the segments, which in some cases taper gradually and in others have a definite constriction between the blade and the haft of the falls, and also in the extent of the indentations in the style crests, which has sometimes been put forward as a difference between I. cretensis and I unguicularis. On the whole, then, it would seem best to refuse specific rank to I. lazica, and reduce it to a local variety of I. unguicularis. It is curious to notice that the broad-leaved forms occur at the western and eastern extremities of the area over which the plant is distributed. Is it due to the dry, poor soil of Greece that its forms are starved and stunted? IT. It. Dykes, Charterhouse, Godalming.

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-- BobPries - 2014-11-12