(1913) Some New Irises by Dykes

Gardeners' Chronicle p.25, July 12, 1913

THE BULB GARDEN.



SOME NEW IRISES.

The hybridisation of species is at best an unsatisfactory pursuit. It may be argued that the success or failure of attempts at crossing plants which seem to be only very distantly related to one another may throw some light on the real relationship between them, but it is at least doubtful whether any inference can be drawn from the non-success of such, a cross.

For instance, it is known, that Sir Michael Foster tried many times to obtain hybrids of Iris tectorum, and similar attempts were also made in the south of France, where there is usually more chance of obtaining sound seeds of Irises than in our variable climate. These attempts remained fruitless, and it seemed as though I. tectorum would not unite with any other species. More recently, however, its pollen has fertilised the Loppio variety of I. cengialti and also a form of I. chamaeiris.

that I. Loptec is doing well in Herault. Moreover, they have proved so far to be sterile both to their own pollen and also to the pollen of either parent. It is, however, a curious fact that such plants go to the trouble of forming capsules in which the seeds do not develop. Even a hybrid between such apparently close relations as I. Korolkowii and I. stolonifera produces huge capsules 5 inches long which contain not a single seed, though the meaning of this apparent waste of energy is hard to see.

It is possible that hybridisation only has a stunting and debilitating effect when species are used that are really widely separated. At any rate, several instances of hybrids which are far more vigorous than either of their parents have occurred here this year.

Early in May I was surprised to see that a number of plants which were producing masses of narrow leaves and which had the appearance of being some form of I. sibirica had no signs of flower stems, as all the other sibiricas had.

Closer examination showed, however, that numbers of spikes were developing, and I looked with some curiosity to the reference for the number on the label. To my astonishment the plants came from a cross between I. tenax, a Californian species, and I. Wilsonii, the taller of the two yellow-flowered relatives of I. sibirica, introduced a few years ago from China.

At the beginning of this month these plants were literally covered with flower-spikes and were the most vigorous and floriferous in my garden, each seedling plant producing twenty or more stems. The leaves are of a pale green, distinctly ribbed, about 3 feet long by ½ inch wide, linear in the lower part and then tapering gradually to a point. The stems are a little longer than the leaves — or, at any rate, rise above their drooping tips — and are slender and wiry. They are not, however, solid like those of I. tenax, but have a small hollow running down the centre, a feature which is characteristic of I. Wilsonii. In the vast majority of cases the stems bear a single terminal head of two flowers, though a lateral flower occasionally develops about 4 or 6 inches below. The spathes are long and narrow, as are those of both the parent plants, and are persistently green even when the flowers have withered

The flowers resemble in shape those of I. tenax, except that the standards are not erect but incline outwards, though not to the extent of those of I. Wilsonii. It is remarkable that the flowers have that curiously mottled appearance which is also found in another hybrid between the sibirica and the Californian groups — namely, I. Clarkei crossed with 'pollen of I. Douglasiana. On the falls the white ground is nearly obscured by suffused colour from the close-set, deep-purple veins. Near the end of the styles the ground colour becomes a deep yellow or orange, as in the case of I. Wilsonii. The standards have to a remarkable extent the curious mottled appearance, an effect which is apparently produced by red-purple veins and suffused colour on a slightly bluer ground.

The short perianth tube is purple ae in the mother plant, and what is more surprising is that the plants are apparently fertile even to their own pollen. At any rate, the capsules are now swelling and have not the puffy appearance that usually betrays the absence of contents.

Another instance of a hybrid which surpasses in vigour both its parents comes also from I. tenax, the pollen-parent being in this case I. Purdyi. This has leaves of considerable substance and a polished upper surface, not unlike those of I. Douglasiana, about 2 feet long by 1 inch wide. The leaves do not stand erect, but droop gracefully round the stems, which are about 12 or 15 inches high, closely covered with large tract-like leaves which entirely conceal it. In some cases there is a lateral branch of some inches in length besides the terminal head of two flowers. The flowers are in shape not unlike those of a large I. tenax, being veined with a faint pinkish-mauve on a white ground. In strong sun the colour soon fades to a soft grey, and the old and the new flowers thus form a striking contrast. This plant produced apparently fertile pollen, and capsules are now developing with even' appearance of being sound.

It is curious that some Irises seem to produce true albinos, which breed true, such as I. tectorum alba and I. orientalis alba, which is largely grown under the name of Snow Queen, while others produce white flowers from which indications of the purple shade are not entirely absent. Of these latter, obvious examples are the albo-purpurea variety of I. laevigata and the white form of the true European sibirica. The flowers of the latter have usually some slight tinge of mauve, and that the purple element is there has been strikingly proved by hybridizing one of these white sibiricas with the yellow I. Wilsonii. The resultant plants are very similar to true sibiricas. The tall, hollow stems raise their head of three or four flowers well above the foliage, and the colour of the flowers is, as far as I know, entirely new among sibiricas. The falls have rounded blades, which are held out stiffly and not allowed to droop. They are veined with pale sky-blue on a creamy white ground, which near the margin is entirely obscured by suffused colour from the veins. Near the end of the styles the white ground is more conspicuous and the veins become violet. Further back still the ground becomes yellow, and the yellow colour of the haft of the talks contrasts with the blue of the styles and standards. This plant seems also to be readily fertile, though it still remains to be seen whether the capsules now developing will contain sound seed. The hybrids are very vigorous, for each seedling plant has produced from ten to twenty flower stems.

A hybrid which is distinctly less desirable than either of its parents has resulted from the crossing of I. chrysographes with pollen of I. Forrestii. The plant is very similar to I. chrysographes, but the wonderful velvety richness of the latter has given place to a violet-blue colour. The flower retains, however, the bright yellow reticulations on the falls, from which I. chrysographes takes its name.

Another new hybrid, which it is unnecessary to describe beyond saying that it is an exceptionally vigorous sibirica, with as many as eight flowers on a stem, has resulted from crossing I. Wilsonii with pollen of typical I. sibirica. The shape of the flowers is somewhat different, especially in the standards, which are unusually large; but in other ways the influence of I. sibirica seem6 to have entirely dominated that of the Chinese mother- It will be interesting to see whether the plants prove to be fertile and what the second generation will give us. W. R. Dykes, Charterhouse, Godalming.

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-- BobPries - 2014-07-14