Herbs, perennial, cespitose, light green to olive or ashy olive, sometimes with purplish base when dry, to 4 dm, not glaucous. Stems simple, 1.2-2.5 mm wide, glabrous or scabrous, margins usually entire, similar in color and texture to stem body. Leaf blades usually glabrous, bases occasionally becoming fibrous but not persistent in tufts. Inflorescences borne singly; spathes green to purplish, glabrous or scabrous, keels usually entire; outer 22-50 mm, 10-32 mm longer than inner, tapering evenly towards apex or occasionally slightly constricted proximal to apex, margins distinct or rarely connate basally to 1 mm; inner with keel usually gibbous, hyaline margins 0.1-0.3 mm wide, apex acuminate to acute, ending 0.4-3.5 mm proximal to green apex. Flowers: tepals white to pale blue, bases yellow; outer tepals 7-12.7 mm, apex rounded to emarginate, aristate; filaments connate ± entirely, stipitate-glandular basally; ovary similar in color to foliage. Capsules light to dark brown, globose, 3-5 mm; pedicel spreading to ascending. Seeds globose to obconic, lacking obvious depression, 0.5-1 mm, granular to rugulose. 2n = 32.
Much like no. 2 [Sisyrinchium albidum Raf.], but the spathe mostly solitary, its outer bract elongate and foliaceous, 2.5-4.5 cm, the inner ones 1-2.5 cm; tep white to pale blue, rarely yellow; 2n=32. Prairies, meadows, sandy places, and open woods; Wis. and Ill. to Minn., S.D., Okla., and Ark. (S. kansanum)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.