Monday, January 4, 2021

IRIS SEPAL TECTONICS

By Sylvain Ruaud

'Aliquippa' illustrates the old style, narrow-petaled,
airy and open aspect of early diploid hybrids.

The progress made with irises has not been limited to enriching the colors of the flowers. They have also focused on improving the holding power of the iris flowers in order to present more elegant and longer-lasting flowers. The most fundamental progress has been the transformation of the sepals (falls), but the petals (standards) themselves have evolved. Originally, they were light, gracefully arched over the sexual parts. But their lightness left only a brief period of perfect presentation. In nature this was not inconvenient because fertilization must occur soon after the flower blooms; that wind or rain crushes the petals was of no consequence. In our gardens on the other hand, it is preferable that the flowers last as long as possible. The hybridizers, therefore, worked on strengthening the petals.

"Ruban Bleu"--image by Christine Cosi

By selecting flowers with increasingly thicker petals, and by retaining those that could be held quite strong, either because of the robustness of the ribs, or because of a very solid shape. But on the other hand, the arch shape gradually gave way to a cup shape, therefore open on top, or to a tulip bud presentation, therefore closed. The elegance in these cases comes from the undulated or serrated edges.

'Chevalier De Malte'--image by Christina Cosi

As far as sepals are concerned, the evolution has been even more remarkable. The big drawback of iris sepals is that they have very thin original attachments. This is not an anomaly: the sepals were originally intended to open wide and fold down to allow insects easy access to the sexual parts. In fact, they resembled leaves of forget-me-not flowers, starting from the area of attachment of the floral parts above the ovaries, a thin and narrow "tail", spreading out in an ovate shape, attenuated at the base, obtuse at the tip. By the effect of selections, the breeders have managed to obtain heart-shaped sepals, thus widening very quickly. This is true for large irises (TB, BB, IB), not yet for dwarf irises.

'Cumulus'--image by Rene Leau

At the same time, as for the petals, the flesh of the sepals thickened, taking a texture close to that of the magnolia petals. Gradually the sepals have had a better hold: instead of hanging sadly, they have straightened, taking in turn an arched shape. But the transformation did not stop there. The goal was sepals standing as close to the horizontal as possible.


'Prince Of Monaco' shows the mid-century advance in substance
that resulted in more flaring petals.

Another means of maintaining the sepals in this position  was thus to select the plants whose parts developed quickly in width, taking this cordate form mentioned above. We speak of "overlapping" sepals, i.e. those that leave no space between them and even overlap, a bit like the tectonic  plates of the earth's crust. The flower gains in size what it loses in reproductive accessibility: in many modern varieties the overlapping of the sepals partially  or totally conceals the stamens and styles. In a hybrid, this does not matter since pollination is exclusively  ensured by man.


'Impresario'--image by Ldislaw Muske

 In addition, the appearance of the ripplings on the iris flowers allowed a better holding of the sepals. This is the principle of the corrugated sheet, where rigidity is achieved by the movement given to the metal: it is obvious that the corrugated varieties have more rigid and upright sepals than the flat varieties (we could say "tailored").


'Parisien'--image by Christine Cosi

Thus, from soft sepals quickly taking a folded position, in about 70 years, we have reached almost horizontal, wavy or even creped sepals, which keep the flower elegant and fresh for several days, allowing to see open on the same stem several staggered flowers, a little like we are used to see in gladioli or cannas. It is obviously more spectacular.


'Butterlicious' shows the modern version
with bubble ruffling, flare, and wide, overlapping hafts.

Does this mean that the iris flowers have reached perfection without any possibility of improvement? The answer is no. Iris flowers will continue to evolve, not necessarily to fundamentally transform the flowers we enjoy today, but to bring other forms. This is what Richard Cayeux imagines for the iris of the future when, in his book "L'iris , une fleur royale", he evokes the bearded irises of the third millennium: "We can already imagine new models of iris flowers today: "spiders" irises (with very long and very narrow divisions...), irises with lash-lined divisions..." as well as flowers with the appearance of I. paradoxa, i.e. with sepals "very small, horizontal, with a strong black beard and purple and shimmering petals clearly larger". He forgot to mention the opposite situation: petalless irises, i.e. with a flat shape, a bit like that of Japanese irises, where the six flower pieces are sepals or pseudo-sepals, overlapping widely. This is a little bit the case of the so-called "flatties" varieties that we already find nowadays. The movements of these spread sepals will not have the same consequences as those of the earth's tectonic plates, but if these forms were to develop widely, it would still be, in the little world of irises, a kind of earthquake.

Editor's Note: Butterlicious, Prince of Monaco, and Aliquippa courtesy of Mike Unser.

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