Iris prismatica

Rhizomes superficial or only slightly buried in peaty soil, cordlike portions usually 1-branched, 40 cm × 2-5 mm, bearing scalelike leaves at nodes; nodal roots absent. Stems simple or 1-2-branched, 3-8 dm. Leaves: basal with blade slightly ribbed, 3-6 dm × 0.2-0.5 cm; cauline 1-4, erect. Inflorescence units 1-3-flowered, branch units 1-2-flowered; spathes pale brown, narrowly lanceolate, 2-4 cm, scarious or partially membranaceous. Flowers: perianth pale blue or blue-violet; floral tube 0.2-0.3 cm; sepals pale violet, veined deep violet basally, ovate, 4-5 × 1.3-2 cm, base abruptly attenuate; petals lavender, oblanceolate, 3.5-4.5 × 0.7-1.5 cm; ovary trigonal, sharply angled; style arched, narrow, 2-3 cm, crests divergent, quadrate, 0.5-0.7 cm, margins serrate; stigmas sharply triangular; pedicel somewhat flattened, 3-7 cm, exserted from spathe. Capsules sharply 3-angled, almost winged, 3-4 × 1.2-1.4 cm, concave faces 6-14 mm wide. Seeds in 1 row per locule, buff to dark brown, pyriform, with convex sides, 3-4 mm, smooth. 2n = 42.

Flowering Apr--Jul. Swampy, peaty soil; Ala., Conn., Del., Ga., Ky., Maine, Md., Mass., N.H., N.J., N.Y., N.C., R.I., S.C., Tenn., Va.

Lvs linear, erect, 5-7 dm נ3-7 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.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.