1924, Iris carolina

Addisonia, page 49, plate 313, 1924 Gallery of Iris Plates from Addisonia

IRIS CAROLINA

Carolina Blue-flag

Native of the southeastern United States

Family Iridaceae Iris Family
Iris versicolor Walter, Fl. Car. 67. 1788. Not I. versicolor L. 1753.
Iris Carolina Radius, Schr. Nat. Ges. Leipzig 1: 158. pi. 3. 1822.


The name Iris is from the Greek meaning rainbow, and is applied because of the bright, usually varicolored parts of the flower. When, in 1822, Justus W. M. Radius described and figured, in color, Iris Carolina, little did he suspect that the species he was proposing was the most generally distributed iris in the low country of the Carolinas and Georgia. It was the rediscovery of this plant that is largely responsible for the study of North American Iris, some of the results of which are here indicated.

The nearest relative of Iris Carolina is Iris versicolor; these two doubtless had a common ancestor in the Appalachian highlands before the ice-age. As far as we know, this species was not driven from its native haunts by the glacier; it evidently has had a long and peaceful existence at the South. A relatively mild climate and a uniform soil has, apparently, resulted in less modification in its structure than in the case of Iris versicolor, which has had much to contend with, both in severe climates and variety of soils. The circular, lozenge-like seeds borne in one row in each carpel or capsule-cavity would indicate a more primitive type of fruit.

Iris Carolina prefers a black silt loam with somewhat stagnant water, where partial shade softens the glare of the full sun; the dampness of its habitat protects it from forest fires. It is common in the Coastal Plain from Virginia to northern Florida, and thrives equally well in the primeval swamps and in artificial habitats; it also occurs in the Piedmont and on the edge of the Blue Ridge, its primeval home. There it may be found growing side by side with some of its preglacial companions such as the typically "southern" bamboo {Smilax laurifolia) and the "northern" sweet-gale {Myrica Gale). Although the flowers are usually deep-tinted, pale forms and even albinos are occasionally observed. The type specimen is merely said to have come from " Carolina " — whether North or South we do not know. The specimens from which the accompanying illustration was made were sent from near Hartsville, South Carolina, by William C. Coker in 1919. They have flowered in the Garden in each succeeding year.

The Carolina blue-flag has a stout horizontal rootstock. The leaves are erect and mostly five to eight together, with narrowly linear, attenuate, pliable, glaucous blades up to one to two feet long. The flower-stalk is slender, as tall as the leaves or taller, often with a slender branch above the middle. The flower-cluster exceeds the leaves, elevated on a purple or green peduncle. The main bract is much shorter than the leaves. The flowers are much exserted from the involucre. The main bracts of the involucre are not foliaceous. The pedicels are one to two inches long. The hypanthium, surrounding the ovary, is shorter than the pedicel and bluntly three-angled. The perianth-tube is narrowly funnelform, about one quarter of an inch long. The three sepals are spreading, pandurate, two and a quarter to two and a half inches long ; the blade is cuneate to elliptic-cuneate, lilac-purple or violet, with decided purple veins, crestless ; the claw-like base is broad, nearly or quite half as wide as the blade, green or yellow-green and veined with purple, with a green or yellow ridge running half way up into the blade. The three petals are erect, spatulate or elliptic-spatulate, one and a quarter to one and three quarters inches long, about two thirds the length of the sepals; the broad yellowish claw shorter than the blade, which is deep or pale lilac and veined with purple. The three style-branches are linear-cuneate, one and a half to two inches long, two fifths to three fifths of an inch wide, with a lilac rib and two pale edges. The style-appendages are curled inward, two fifths to three fifths of an inch long, bluntly erose-toothed, semi-orbicular, or widest slightly above the middle or below it. The stigma is shallowly toothed, but otherwise entire. The three stamens are one and an eighth to one and a quarter inches long, the anthers and filaments about equal in length, or the anther a little the longer. The capsules are ellipsoid to ovoid-ellipsoid, mostly one and a half to tw^o inches long, with a slight ridge on each side and a groove along each rounded angle, obtuse or sometimes short-beaked as a result of the failure of the ovules near the apex of the ovary to develop into seeds; the earlier ones of a cluster on pedicels exceeding their own length, the later ones on shorter pedicels. The seeds, in one row in each carpel or cavity of the capsule, are suborbicular, thick lozenge-shaped, pale brown and very corky, about five twelfths of an inch in diameter or less.

John K. Small.

For more information on historic Irises visit the Historic Iris Preservation Society at

-- BobPries - 2014-12-08