| Flor. Cab. 66. 1788;
| Sweet, Brit. Flower Garden vol. III. table 274 (1828)
| Curtis's Botanical Magazine, table 2886 under the name I. tripetalaDescr. Root "creeping" ELL. Stem one and a half to two feet high,, terete, bearing a few leaves; but most of them spring from the root and are linear, ensiform, striated, acuminated, slightly falcate: uppermost ones spathiform. Flowers, three or four from the extremity of the stem, each subtended by its own foliaceous spatha. Peduncle shorter than the spatha. Exterior segments of the corolla broadly oval, much waved, somewhat clawed, large, of a beautiful bluish purple mottled with white, and distinctly marked with deeper purple lines, the claw whitish, with yellow-brown reticulations : inner segments very small, linear-lanceolate, acuminated, the segments incurved, entire, or with three teeth at the extremity, the middle tooth being longer and much acuminated : the colour a pale purple. Divisions of the styles purple: stigmas toothed, bifid and almost blue.Communicated by David Falconer, Esq. from his collection at Carlowrie, Edinburgh, in May, 1828. It is a native of Carolina, first described by Walter, in his Flora of that country: nor does it appear to have been known to any other Botanist except Mr. Elliott, who, however, speaks of it as being very much circumscribed in its locality.The inner segments of the corolla, I do not find to be by any means constantly three toothed. Sometimes they are quite entire.
| Dykes in The Genus Iris, 1913; under the name I. tripetala;Description (taken partly from herbarium specimens and partly from Foster's notes on a specimen which he had in cultivation). Rootstock , a somewhat slender rhizome of wide-creeping, almost stoloniferous character. Leaves , linear, finely ribbed, green with a red edge, 12-15 in. by ¼-1 in. Stem , about a foot in height, dark in colour, bearing several reduced leaves and a terminal 1-2-flowered head. One or two lateral branches are sometimes produced. ) Spathes , narrow, pointed, quite herbaceous, rigid, unequal, the outer being usually less than half the length of the inner valve. Pedicel , about 1 in. long. Ovary , trigonat with a groove running down each angle. Tube , funnel-shaped, less than 1 in. long. Falls . The suborbicular blade is about as long as the narrow haft. The colour of the blade is a bluish purple, mottled with paler patches and veined with thin but conspicuous darker veins. The signal patch is white with some trace of yellow in the centre. The haft is whitish with yellow-brown reticulations; 2 in. long. Standards , ½ in. long, oblanceolate, erect, more or less tridentate, with the central tooth much longer and larger than the laterals. (It is possible that the standards are sometimes not toothed; this was apparently the case in Foster's specimen.) Styles , narrow. Crests , large, subquadrate. Stigma , entire, semi-circular in outline. Filaments , very short. Anthers , Pollen , Capsule , 3/4-1 in. long, much rounded trigonal, the sides being hardly at all concave. Seeds , thick, compressed dark red-brown discs, in a single row in each loculus.Observations.This little known Iris is apparently no longer in cultivation in Europe. It flowered once with Foster at Shelford but it needed a hothouse temperature in July to induce the flower to open. Some details of the description here given are taken from Foster's MS. notes.In many ways this Iris resembles the American forms of I. setosa, which are usually known as I. Hookeri or setosa -Canadensis. It differs from that plant, however, in having linear leaves, conspicuously unequal green spathe valves of a thick rigid texture, a rounder, less sharply trigonal ovary and capsule and disc-shaped seeds.In Van Geel's Sertum Botanicum r. there is a figure of this Iris, together with the statement that it was first known in Europe as flowering in May, 1828, in the garden of David Falconer, at Carlowrie, near Edinburgh. Nothing is known of its requirements in cultivation but it would probably require a warm position in soil that was not too dry in spring and early summer.
| Small in Addisonia 12: 1, 5. Mar 1927, illustrated in color plate 387, offers the following description under Iris tripetala: "The environs of the second botanic garden in America contained four species of the genus Iris. At that time, in the early ‘80s of the eighteenth century, one of these, the violet-iris (Iris verna) had been seen and described by Linnaeus. This species, a small plant, represented one group of the genus Iris. The other three species, larger plants, and all unnamed at that time, each represented a different group. Thomas Walter named two of these, Iris hexagona and the subject of this note. The third species he erroneously referred to a more northern one.This blue-flag still stand alone in its group. Its most prominent character is the relative size of the calyx and corolla. The petals are very small. It was this character that suggested the specific name to Walter. However, he considered, perhaps inadvertently, the whole perianth to be corolla and named it with reference to the three large sepals which are so prominent compared with the minute petals of the true corolla. Its coarse wiry rootstock also distinguishes it from all our southern blue-flags. In its involucre and three-angled pod it is related to the Iris versicolor group.The modern evidence indicates that the ancestors of this blue-flag advanced from the ancient interior highlands, as the Coastal Plain rose from the sea, along the tributaries of both the Atlantic Ocean to the eastward and the Gulf of Mexico to the southward. However, it, in the lapse of time, not only burned its bridges behind it as it advanced, but even left the immediate vicinity of creeks and riverbanks and betook itself to low places in flatwoods, in the vicinity of ponds and ditches where water stands part of the year and at other tomes remains close to the surface. In migrating, the ancestors of the present plants, passing into the Atlantic Coastal Plain, developed somewhat different offspring from those going to the Gulf Coastal Plain. The form here illustrated may be considered the botanically typical one, for it came from the region of Walter's South Carolina botanical activities.This iris there favors low meadow-like areas adjoining "bays", as pine-barren ponds are there termed; the iris plants occur in great masses in the black boggy soil that surrounds the "bays", with such plants as yellow-flycatchers (Sarracenia), spider-lilies (Hymenocallis), and other southern bog plants.
The shading of violet and yellow on the sepals gives the flower a very soft tone quite different from that of any of our other native species.The bay-flag has a long coarse-wiry zigzag or spiral, sometimes partly fibrous coated rootstock. The leaves are usually three to five together, erect, grass-like. The blades are narrowly linear-attenuate, glaucous, especially near the base, at least when young, finely ribbed. The flower-stalk is mostly one to one and a half feet tall, slender, green zigzag. The flower is solitary at the top of the stem, or sometimes an additional one is borne on a branch from the upper node of the stem, erect, somewhat fragrant. The involucre subtending the flower is narrowly cylindric, two to two and a half inches long, of two main bracts, the inner one about twice as long as the outer or less, acute or mucronate. The pedicel is one and a quarter to one and three quarters inches long, about as long as the hypanthium plus the perianth-tube. The hypatium surrounding the ovary is bluntly three-angled, green, much shorter than the pedicel. The perianth-tube is obscurely three-angled, slightly dilated upward, quite as long as the hypanthium. The three sepals are arching and drooping, remate, two to three inches long, crestless. The blade is suborbicular or oval, longer than the claw, violet, varying from pale to dark, paler without than within, except the yellow spot at the base and the white flecks that run off from the yellow. The claw is about one third of an inch wide, greenish within and bordered with violet, flecked or lined all over with violet, without the green is flecked only along the violet edges. The three petals are erect, inconspicuous, about a half inch long, elliptic-lanceolate or oblanceolate, the body contracted into a slender tip, greenish at the base, violet above, with several deep-colored lines. The three stamens are an inch and a quarter to nearly an inch and a half long, with the filament and anther about equal in length. The filament is green at the base, violet where it meets the violet tinged anther. The three style-branches are broadly linear, about an inch and a quarter long, violet, slightly paler at the edges than at the middle. The stigma is entire. The style-appendages are semi-elliptic, curled upward, shallowly toothed above the middle, much overlapping, deep violet. The capsule is ellipsoid, an itch and a quarter to an inch and a half long, bluntly three angled or three sided, with a ridge on each face, shorter than the pedicel. The seeds, borne in two rows in each capsule-cavity, are somewhat corky, semicircular or lunate, about a quarter of an inch in diameter."Unfortunately the specific name tripetala had to be later rejected since it had been used by Linneaus's son 6 years prior for what later became Morea tripetala.