(1918) Regelias by Dykes
The Garden p.460, December 14, 1918
By W. R. Dykes.
Thw name Regelia was given to a small group of Asiatic Irises in honour of the late Dr. Regel of St. Petersburg, the Russian botanist to whom we owe the introduction to our gardens of many good plants from Central Asia.
The members of this group are not nearly as common in our gardens as they deserve to be, and this is probably due to the fact that they have been classed with the Oncocyclus Irises, which most gardeners have given up as hopeless in our moist climate. The Regelia Irises are, however, much more amenable to cultivation. The rhizomes increase rapidly under suitable conditions and, moreover, seedlings are easily raised.
There is one essential point in the cultivation of these Irises and that is that the plants must have a complete rest for two or three months in the late summer. This can be obtained by putting a temporary roof over their heads if they are grown in a position that lends itself to this treatment or by lifting the plants in July and not replanting them until October. The latter method is followed here, though I should prefer to leave the plants undisturbed and cover the beds with skeleton frames such as the late Sir Michael Foster used with such success at Shelford.
In choosing a position for these Irises, it should be remembered that they require all the sun that our climate will give them and that a raised or sharply sloping bed will ensure that the soil about their rhizomes is at no time waterlogged. The soil should be rich in humus and plentifully supplied with lime.
The Regelia Irises are obviously closely allied to the Oncocyclus group, for the seeds of both groups are indistinguishable and yet quite unlike those of any other group of Irises. They are remarkable for the possession of a kind of cream-coloured collar, which forms, as it were, the attachment between the seed proper and the placenta in the seed-vessel. The rhizomes of the two groups are very similar and characteristic, and the chief points of difference are that the Regelia species produce two or three flowers on each stem in place of the solitary flower of the Oncocyclus and that their beards are linear and do not consist of a broad patch of irregularly scattered hair, such as is found in the Oncocyclus species.
The first Regelia Iris to be discovered was Bunge's I. falcifolia, from the deserts east of the Caspian. It is a small species with narrow, grass-like leaves and has never apparently been in cultivation. The next was the well-known I. Korolkowi, which was sent to St. Petersburg from Turkestan by General Korolkow. Of this Iris there are many colour forms, but all are cliaracterised by the conspicuous veining and by the dark beards, which, however, project so little on to the sharply reflexed blade of the falls as to remain practically hidden under the style branches.
In some specimens the ground is cream-coloured and the veining either olive-green or 'brown-urple. In others the ground is slightly suffused with purple, while in the variety concolor the whole flower is of a uniform red-purple colour with darker veins.
I. Korolkowi has a much more compact rhizome than that of I. stolonifera, of which the stolons are often much longer. Plants of this species are sometimes labelled Leichtlini or Vaga, but stolonifera was the name first given and, moreover, accurately describes the habit of the plant. The flowers, of stolonifera are very beautiful in some of its colour forms. The edges of the petals are always waved, a character that has been transmitted to the hybrid with Korolkowi. The circumference is of some shade of brown-purple, while the centre has veins of the same colour on a bluish ground, and the effect of this colouring is very remarkable. In some cases the veining is very dark and velvety, and I have one imported plant, which came by chance among a number of I. Hoogiana, of which the colour is wholly a very rich dark blue-purple. One curious point about I. stolonifera is that the colour of its beard is apt to varv. In some years it is yellow in front and blue behind. While in others, it is wholly blue. It is not yet known to what this change is due, but it is a phenomenon which does not seem to occur elsewhere among Irises.
I. Korolkowi and I. stolonifera hybridise freely with one another and have given me some delightful forms, one of which is illustrated on page 460. It is distinguished by its conspicuous beard of deep blue, in which the deep tone of the beard of Korolkowi seems to have combined with the colour of that of stolonifera. The flower is of a curious and uncommon shade of red-purple. There is also in cultivation here a hybrid which Foster raised and called Korvag. It is similar to the plant sketched, but the colouring is much paler and the veining is accordingly much more prominent.
I. darwasica or Suwarowi is perhaps no longer in cultivation. It is a small plant, not unlike a reduced stolonifera, but distinguished by having all its petals tapering gradually to a point.
There remains only I. Hoogiana, the latest addition to the group and a truly magnificent Iris. The stems grow to a height of more than 2 feet and produce large flowers of a uniform shade of blue-purple with bright orange beards. The shade of colour varies in different specimens and may be as pale as that of the palest I. pallida The beard is broad and very conspicuous and tapers to a sharp point in front. About the whole flower there is an extra-ordinary appearance of refinement and breeding, and I. Hoogiana is certainly the most striking new species of Iris. It is a vigorous grower, and although it is late in beginning to grow in the spring, it then grows so fast that it is at its best in May with the other members of the group. There is some hope, too, that its habit of lying dormant till winter is practically over may enable us to leave it undisturbed in the ground. Now that I have a large number of plants, I certainly mean to try the experiment next year.
The Regelia Irises, and in particular I. Korolkowi, have been largely hybridised with Oncocyclus species to form the well-known Regelio-cyclus hybrids. These possess the vigour of the Regelias and something of the form and colouring of the elusive Oncocyclus species. Hybrids with Bearded Irises are less common, but I have crosses of Korolkowi both with a purple and with a yellow Chamaeiris. Both are interesting and quite distinct. With I. stolonifera I have so far failed to obtain any pleasing hybrid. There are too many colour elements present, and the struggle between them results in a nondescript confusion and patchiness. Hoogiana gives promise of better results, but it is so beautiful in itself that it seems almost a pity to spoil its beauty in order to satisfy our curiosity as to how far its influence would prevail in a hvbrid.
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