Staminate spike peduncles 1.2-4.5 mm. Proximal cauline pistillate spikes sessile, globose to ovoid. 2n = 36, 40. Fruiting mid Apr-early Jul. Open, well-drained sandy, loamy, and loess soils in prairies (grazed and ungrazed) and ponderosa pine woodlands; 100-1500 m; Alta., B.C., Man., Ont., Sask.; Colo., Ill., Ind., Iowa, Kans., Mich., Minn., Mo., Mont., Nebr., N.Mex., N.Dak., S.Dak., Wis., Wyo.
Perigynium (1.5-)1.7-2.2 mm wide; stems usually scabrous below the infl; ventral face of sheath of upper cauline lf only shallowly concave, its cleft not extending more than 1(-1.5) mm below the junction with the blade; 2n=40. Mainly on the prairies and plains to the w. of our range, but extending e. to Minn., Io., n. Mo., and occasionally Ind., Mich., and s. Ont. (C. heliophila; C. inops ssp. h.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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