Viridula: 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; spike 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]
	Perigynia glabrous. NOT [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 group have convexly 3-sided to terete achenes with tight fitting perigynia and a stipe-like base about equal to beak in length)]
	Beak over 0.5 mm long and usually visibly bidentate (teeth hyaline in C. sprengelii, inconspicuous in C. viridula, very short in C. oligosperma).  NOT [Beak absent or less than 0.5 mm long; if more than 0.5 mm long, then terminating in an orifice without teeth]
	Style jointed at base and deciduous from achene, if present at maturity, breaks off readily when manipulated. NOT [Style continuous with achene and persisting at maturity as a long, curved or straight prong]
	All pistillate spikes sessile or nearly so; base of plant lacking brown fibers.  Section Ceratocystis (C. cryptolepis, C. viridula) NOT [Lower pistillate spikes with filiform stalks 2-7+ cm long; basal sheaths shredding to a mass of brown fibers persisting on crown.]
	Perigynia 1.8-3.5 (3.9) mm long; beak about one-quarter the length of perigynium, faintly bidentate; most perigynia spreading to ascending, a few at base of spike reflexed.  NOT [Perigynia 3.5-4.8 mm long; beak about one-half the length of perigynium, finely but visibly bidentate; most perigynia spreading to reflexed, a few at top of spike ascending.]