1924, Iris Savannarum
Addisonia page 57, plate 317, 1924
Native oj the interior oj peninsula Florida
Family Iridaceae, Iris Family
Iris savannarum Small, sp. nov.
In abundance and size of flowers and fruits the prairie iris of the Florida peninsula outclasses our other species. The colonies are usually to be measured by the acres, often in extent further than the eye can reach vast green seas of upward-pointing myriad sabres, broken only by brilliant flecks or patches of color in the early spring when the plants bloom. In the summer and sometimes in the fall, the stretches are just as green, but in addition to the leaves there are countless clusters of bright green cucumber-like pods, at first nodding from the stout erect stalks. At length the pods become so heavy that they are borne to the ground, and then lie on the turf, or if the water be high, float, ultimately decay, and then discharge the seeds which resemble brown corky lozenges. As in all the swamp-inhabiting species of iris, the seeds are buoyant as a result of the thick corky covering. Thus each seed with its float is not only well protected, but it can finally start a new colony of Iris at some destination determined by current or wind.
Like other Florida species of Iris, Iris savannarum has quite successfully "burned its bridges" behind it, for there is no vestige of it between peninsular Florida and the elevated Appalachian Highlands whence it, or its immediate ancestors, descended after the most recent extensive elevation of the continent. Its remote ancestors may have been those which gave rise to Iris Carolina and Iris versicolor, but having passed into a land of perpetual growth and peculiar environment it assumed different characters. Its mode of life is now very simple. It inhabits prairies or savannahs wholly monotonous in topography with a climate almost equally monotonous. Its habitat is a rich loamy sand or a poor sandy loam, either wet all year or dry all year, as far as surface water is concerned. In most of the habitats the water-table is near the surface in the dry season. In the wet season the water on the surface vacillates with the local rains, varying from a few inches to a foot or more in depth.
The type specimens were collected on the southern side of the Caloosahatchee near Olga, Florida, in December 1923, by the writer, and are in the herbarium of the New York Botanical Garden, Specimens flowered at the Garden in the spring of 1924; from one of these the accompanying illustration was made. It is planned to set out plants in the open next spring in order to learn if they will be hardy and adapted to cultivation at the North.
The prairie blue-flag has a very stout, fleshy rootstock. The leaves are erect, several together, w^ith bright green or glaucescent elongate linear-attenuate blades often up to three feet long. The flower-stalk is nearly three feet tall or less, almost or quite straight, nearly terete, somewhat glaucous, simple, or with a branch above the middle, or below it, which is subtended by a foliaceous bract. The flower or flower-cluster is exceeded by the subtending bract. The pedicel is slightly longer than the ovary in anthesis. The hypanthium, covering the ovary, is bluntly three-angled, and often with the faces ridged. The perianth-tube is funnelform, fully a half inch long or shorter, shorter than the ovary. The three sepals are spatulate, four to five inches long; the blade is elliptic to ovate-elliptic, longer than the claw, mainly blue or pale violet, except the flecks of white and lines of deeper blue on either side of narrowly linear yellow finely pubescent crest which extends up to about the middle of the blade; the claw^ is less than a half inch wide, light green, distinctly striate with darker green within and ribbed. The three petals are linear to narrowly linear-spatulate, three and a quarter to three and three quarters of an inch long; the blade is deep blue, about two thirds as long as the claw, blunt or acute; the claw is channeled, green with darker lines and pale margins. The three stamens are nearly an inch and three quarters long, with the filament about half as long as the linear anther. The three style-branches are linear-cuneate, two to two and a half inches long, purple-tinged with pale margins within. The style-appendages are inequilaterally ovate, about three quarters of an inch long, sharply and irregularly toothed. The stigma is broadly two-lobed, with each lobe dentate-crenate. The capsules are ellipsoid or nearly so, three to four inches long or sometimes longer, often stout-beaked, with a slight ridge on each face and prominent parallel ridges on either side of the rounded angles, corky-walled. The mature pedicels are shorter than the capsules. The seeds, borne in one row in each carpel or cavity of the capsule, are very corky, circular or somewhat uneven from mutual pressure, brown, half an inch in diameter or less.
John K. Small.
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