Iris prismatica Pursh
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Lvs linear, erect, 5–7 dm × 3–7 mm, from slender, widely creeping rhizomes; stems slender, 3–10 dm; fls on slender pedicels much exceeding the spathes, 6–8 cm wide, violet to blue-violet; pet erect, obovate, with a slender claw; sep spreading-reflexed, veined with dark violet and variegated with white, the claw greenish and purple veined; fr sharply trigonous, 3–5 cm, apically dehiscent; 2n=42. Marshes, swamps, and damp meadows; near the coast from N.S. to Ga., and in the s. Appalachians. June, July.
slender blue flag