Oryzopsis asperifolia
 
White-Grained Mountain Rice-Grass

Flower

Fairy Hill NCC Property, 35 km North of Regina on Highway #6
11-May-2021

The callus is blunt and densely pilose.  The filaments from two of the three stamens are visible in this photo.  Note the anthers have already fallen from the filaments.

The following items are taken from keys in Flora of Saskatchewan, Fascicle 4, Grasses of Saskatchewan by Anna L. Leighton and Vernon L. Harms.  Family Poaceae is first divided into tribes, then the tribes are divided into genera, and the genera divided into species.  However, there are a number of tribes that are very difficult to distinguish morphologically.  These are grouped into a large, artificial tribe I call "Multitribe".  Multitribe is then divided into groups, and each group is then divided into genera.  The answers are in the order you would normally work through the keys.

Stipeae: Answers to key questions leading to this tribe. 
Mature inflorescence, if breaking into units, then the units not as below; NOT [Mature inflorescence breaking into spikelet units consisting of a sessile fertile spikelet, a hairy pedicel with or without a sterile spikelet at tip, and a hairy rachis joint, all arising at the same point (a node) in specialized panicle branches called rames]
Spikelets not as below; sterile florets if present, either located distal to the fertile floret(s) on the rachilla or paired and attached at the base of a single fertile floret, not paired with the upper glume as below; lemma and palea variously textured, enclosing the flower or not; disarticulation usually above the glumes; NOT [Spikelets usually dorsally compressed, appearing 1-flowered but containing 1 fertile floret and 1 sterile floret, the latter attached to the base of fertile floret opposite the upper glume, resembling the upper glume, and together with the upper glume enveloping the fertile floret; lower glumes minute (sometimes absent) to 3/4 as long as upper glumes and typically wrapping most of the way around the pedicel at base; fertile floret seed-like with chartaceous-indurate lemma and palea enclosing flower and fruit; disarticulation below the glumes with rare exceptions]
Spikelets 1 to many-flowered, subtended by a pair of glumes (only 1 on lateral spikelets in Lolium); palea margins enclosed or not; plants of dry or wet habitats; NOT [Spikelets 1-flowered, lacking glumes; margins of the palea tightly enclosed by the lemma margins on female or perfect florets; plants of wetlands, often emergent aquatic]
Inflorescence not as below; if a terminal spike, then the lateral spikelets attached edgewise to the rachis with inner (upper) glume wanting (as in Lolium); NOT [Inflorescence a terminal spike with sessile or subsessile spikelets attached broadside at nodes on opposite sides of the rachis]
Lemmas stiff to indurate, firmer than the glumes, surrounding the palea and often overlapping along the margins, closed at the tip as well as at the base, often pubescent; lemma awns (caducous or wanting in some species) terete and encircled at the base by the closed tip of the lemma; calluses usually pubescent, rarely glabrous; NOT [Lemmas and lemma awns not as above; if lemma indurate and enveloping the floret, then glumes distinctly dorsally compressed and calluses glabrous (as in Milium)]
Lemma awns 1, persistent or caducous; lemmas usually pubescent; NOT [Lemma awns 3, persistent; lemma glabrous]

Oryzopsis: Answers to key questions leading to this genus 
Lemma awns 1-32+ mm long; lemmas 1.5-7 mm long; callus to 2 mm long, blunt to pointed but not sharp-tipped; glumes 2.5-13 mm long; NOT [Lemma awns 50-225 mm long; lemmas 7-25 mm long; callus 2-6 mm long, sharp-tipped; glumes 15-45 mm long]
Basal blades green late in the season, overwintering, flat to ± revolute, 4-9 mm wide, tapering at both ends and twisted 180° at base; cauline blades reduced or obsolete, the flag leaf blade at most 1.2 cm long; glumes green with scarious margins and tip; panicle narrow with appressed branches; callus blunt, densely pubescent; NOT [Basal blades not overwintering, usually rolled and narrow, if flat, then to 5 mm wide and not twisted at base; cauline blades ± well-developed, flag leaf blade more than 1 cm long; other features variable]