1927, Iris Shrevei

Addisonia Volume 12, page 13, plate 391, 1927


Interior Blue-flag

Native of the central United States

Family Iridaceae, Iris Family

Blue-flags at or near the western edge of the geographic range of the species typical of the eastern United States should be regarded with suspicion as to true relationships. Preliminary studies have shown that there is very little in common between the Iris in the Mississippi River basin and in the Atlantic seaboard. Some of the species today are represented either on the Atlantic seaboard or in the interior, thus indicating that their ancestors in leaving the ancient highlands took either an eastward or a westward course, or if they followed both courses, the complements have been lost. Other species, east and west of the present mountains, are paired, as it were. Although perfectly distinct, they are closely enough related to indicate that they had a common ancestor in later geologic time.

The species here concerned is the complement, as it were, of Iris versicolor, just as in another group, Iris foliosa is the complement of I. hexagona On the other hand, Iris vinicolor of the Mississippi Delta and Irisfulva wide-spread in the interior have no complementary representatives in the Atlantic Coastal Plain.

The marsh is the home of Iris Shrevei. Large level stretches are often densely covered by the bright green plants with their numerous flower-stalks which hold the showy flowers about level with the tops of the leaves at anthesis. After the flowering season, as the pods mature, the stalk bends at the ground, lies down, and carries the pods to the turf where they lie, mature, and spill their corky seeds which lie ready to be floated away when high water comes.

The plants often grow in a dense turf of grasses, sedges, and rushes. Water-horehounds (Lycopus), mints (Mentha), and bonesets (Eupatorium) are often associated with them, while woody plants — roses (Rosa setigerd), cornels (Svida obliqtia), and button-bushes (Cephalanthus occidentalism —afford partial shade. The color of the flower is mainly lavender, in pale and dark shades. There are occasionally colonies with lavender-blue flowers, and rarely the perianth-parts are almost white. Contrary to what obtains in most of our blue-flags, the flowers are decidedly sweet-scented. The amount of fragrance, however, varies with the different colonies and localities. The type specimens were collected by Ralph Shreve near Farmington, Arkansas, and are in the herbarium of The New York Botanical Garden. The plants of the original collection are hardy in the iris plantation of the Garden.

The interior blue-flag has a stout, often branching, fleshy, widely creeping rootstock. The leaves are erect, usually two or three together, bright green and frequently somewhat glaucous except the often purple bases. The blades are linear-attenuate, up to a yard long, mostly three quarters of an inch to an inch wide. The flower-stalk is erect, about equaling the longer leaves in anthesis, much shorter later in the season, with one or two branches which usually nearly or quite equal the top of the main stem at maturity. The flowers are solitary, paired, or three together at the end of the stem, and often solitary or paired in the upper one or two leaf -axils. The involucre consists of two main short bracts which sometimes reach only to the base of the hypanthium. The pedicel is usually about as long as or slightly longer than the ovary in anthesis. The hypanthium surrounding the ovary is bluntly three-angled. The perianth-tube is turgid-campanulate, much shorter than the ovary, usually about half as long. The three sepals are remate, two to two and a half inches long, recurved-spreading. The blade, which is about as long as the claw or shorter, is oval, or orbicular-oval, mainly lavender or lavender-blue, except the yellow-green blotch near the base, from which white flecks bordered by purple lines diverge. The claw is rather broad, bright green and flecked with purple without, yellowish green and lined with purple within. The three petals are spatulate, nearly as long as the sepals. The claw is green or greenish-yellow, flecked and lined with purple near the base as. in the sepal-claw. The blade is light violet, faintly lined with dark violet. The three stamens are about one and a quarter inches long. The filament, with the dilated lower part yellowish green, is whitish above. The anthers are greenish yellow, shorter than the filaments. The three style-branches are about an inch and a half long, pale lilac or pale lavender. The style-appendages are obliquely lanceolate or ovate-lanceolate, one third to one half inch long, curved upward, coarsely few-toothed. The stigma is entire. The capsule is prismatic-cylindric, two and a half to four inches long, three-sided, usually longer than the pedicel, the angles rounded, the sides with an impressed rib which is three-forked above the middle. The seeds, borne in two rows in each capsule-cavity, are half -circular, corky, brown, often nearly or quite a half inch in diameter.

John K. Small.

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

-- BobPries - 2014-12-09
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Topic revision: r1 - 09 Dec 2014, BobPries
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