Rossii: Answers to key questions in Sedges (Carex) of Saskatchewan, Fascicle 3, Flora of Saskatchewan by Anna Leighton leading to this species. The answers are in the order you would normally work through the key. 

	Stigmas 3; achenes three-sided, occasionally terete, though their shape may be concealed by flattened perigynia. NOT [Stigmas 2; achenes lenticular.]
	Spikes 2 or more per culm, terminal and lateral; spike bracts present on lateral spikes (except in Section Phyllostachyae), lowest bract usually evident, often conspicuous.  NOT [Spikes 1 per culm, terminal; spikes bracts absent.]
	Lower pistillate scales not bract-like or leaf-like but similar in size and shape to individual perigynia (up to twice as long as perigynia in C. magellanica ssp. irrigua). NOT [Lower pistillate scales resembling green, leaf-like bracts much longer and wider than individual perigynia.  Section Phyllostachyae. (C. backii, C. saximontana)]
	Perigynia sparsely to densely pubescent or puberulent (in C. pedunculata pubescence represented by very short hairs scattered near tip; in some species of Sect. Acrocystis, perigynia may be glabrous or virtually hairless, but all members of this section have convexly 3-sided to terete achenes with tight-fitting perigynia and a stipe-like base about equal to beak in length).  NOT [Perigynia glabrous (i.e. lacking a pubescence).]
	Perigynia usually less than 5 mm long but if longer, beak distinctly shorter than perigynium body; pubescence various. NOT [Perigynia 5-7 mm long with beak as long as or longer than perigynium body; pubescence on the perigynia dense, stiff and pointing toward tip.]
	Achenes convexly 3-sided to terete; perigynia tightly enclosing achenes and convexly 3-sided to terete, sparsely pubescent, (rarely glabrous in C. deflexa and C. rossii, pubescent only on ribs in C. tonsa); stipe-like base about equal to beak in length; pistillate spike bracts sheathless.  Section Acrocystis. (C. deflexa, C. inops ssp. heliophila, C. peckii, C. rossii, C. tonsa, C. umbellata.)  NOT [Achenes with +/- flat sides; perigynia loosely fitting achene and variously shaped in cross-section, densely to sparsely pubescent (faintly puberulent with very short hairs scattered near tip in C. pedunculata); pistillate spike bracts sheathing or sheathless.]
	Some or all pistillate spikes basal, i.e. attached near base of plant and borne among leaf bases. NOT [All pistillate spikes cauline, i.e. attached near top of regular, elongate culms and born at or above level of leaf tips.]
	Pistillate scales (excluding awn) usually shorter than perigynia; beak straight or bent; basal spikes few.  NOT [Pistillate scales as long as, or longer than, perigynia; beak straight; basal spikes more numerous than cauline spikes.]
	Staminate spike 4-10 (12.8) mm long with stalks 1-10 mm long, usually visible above pistillate spikes; lowest cauline pistillate spike bract leaf-like, to 7 cm long, usually distinctly longer than inflorescence; perigynia 3 mm long or a little longer with beak 0.8-1.5 mm long.  NOT [Staminate spike 3-5 (5.7) mm long, often hidden by adjacent pistillate spikes; lowest cauline pistillate spike bract leaf-like or bristle-like, 0.7-3 cm long, as long as, or overtopping, inflorescence; perigynia up to 2.5 (3.1) mm long with beak 0.4-0.8 mm long.]