Prairie straw sedge is a graminoid, 30-70cm tall, with 2-5 distant, distinct spikes that are ovoid with bases that are rounded or short-acute and an acute apex. It has 15-80 perigynia in larger spikes, appressed, usually golden brown, 2.1-2.6mm wide, broadest at about the middle, 4-5mm long, conspicuously 6-9-veined abaxially, inconspicuously veined adaxially, diamond shaped in general outline, flat except over achene, base is subacute or acute, margin flat, smooth. Beak is appressed, golden brown at tip, flat, ciliate serrulate, abaxial suture with hyaline, with golden brown margin. Achenes are elliptic to ovate. Sheaths are adaxially conspicuously green-veined nearly to collar, with a narrow hyaline band or sharp Y-shaped region at collar, adaxially firm, summits U-shaped. Each fertile culm has 2-5 blades, usually less than 2.5-3mm wide. Its pistillate scales are reddish brown, its single-veined midstripe is sometimes pale, broady lanceolate, apex is firm, acute to acuminate.