Rhizomes compact, greenish brown or sometimes red-tinged, many-branched, with ringlike scars of old leaves, 1.5-2 cm diam. Stems simple or sometimes 1-2-branched, solid, 3-9 dm. Leaves: basal arching distally, blade bright green, lightly ribbed, linear-ensiform, 6-10 dm × 1.5-2.5 cm; cauline subtending branches, blade 4.5-6 dm. Inflorescence units 1-2-flowered; spathes unequal, outer green, 10-12 cm, herbaceous, inner 6-8 cm, partly scarious. Flowers: per-ianth copper colored or reddish brown (yellow in forma fulvaurea); floral tube hollow to ovary, 2-2.5 cm; sepals widely spreading or arching downward, obovate, with 1-3 prominent veins, 4.5-5.5 cm, glabrous, often with lighter yellow basal signal; petals spreading or declining with sepals, 4-5 × 1.5-2 cm, base gradually attenuate, apex deeply emarginate; ovary green, hexagonal, 1.5-1.7 cm; style convex, not keeled, 1.8-2 cm, crests reflexed, rounded-triangular, margins shallowly toothed; stigmas 2-lobed, lobes pointed, margins entire; pedicel 2-4 cm. Capsules remaining green even after seeds mature, oblong-elliptic, hexagonal in cross section, with 6 equally spaced ribs, short beak, 4.5-8 × 2.5 cm. Seeds in 2 rows per locule, irregular, flattened, 10-15 mm, corky. 2n = 42. Flowering Apr--Jun. Shallow water or low wet areas; Ark., Ill., Ky., La., Miss., Mo., Tenn. Iris fulva hybridizes with I. brevicaulis to produce I. × fulvala Dykes, which has reddish purple sepals; with I. giganticaerulea to produce I. × vinicolor Small; and with I. savannarum to produce I. × cacique (J. Berry) N. C. Henderson.
Lvs ensiform from a horizontal rhizome, 0.5-1 m; stem 0.5-1.5 m, surpassing the lvs; fls 7-9 cm wide, copper-color to brown-orange, reddish-brown, or rarely yellow; tep widely spreading, the claw scarcely a fourth the length of the blade; ovary 6-angled; mature fr 4.5-8 cm, indehiscent; 2n=42. Swamps; s. Ill. and Mo. to Ga. and Pa. Apr., May.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.