Richardsonii: Answers to key questions in Rushes, Bulrushes & Pondweeds plus the remaining Monocots of Saskatchewan, Fascicle 6, Flora of Saskatchewan by Anna Leighton leading to this species. 

	Stipular sheaths free from leaf blades; leaves not conspicuously 2-ranked; leaf blade width various; inflorescences unbranched; NOT [Stipular sheaths fused to leaf blades for about half the sheath length, the tips projecting as ligules; leaves stiffly and conspicuously 2-ranked; leaf blades linear to lanceolate; inflorescences often branched]
	Leaf margins entire; beaks <= 1 mm long; turions soft or firm; NOT [Leaf margins serrate; beaks 2-3 mm long; turions firm]
	Leaf blades ranging from linear-lanceolate to lanceolate, elliptic and ovate, 3-58 mm wide; NOT [Leaf blades linear (i.e. with sides parallel), 0.1-10 mm wide]
	Leaf bases clasping stems; NOT [Leaf bases not clasping stems (slightly clasping in P. alpinus) but may be sessile]
	Leaf blades ovate-lanceolate to narrowly lanceolate, 1.6-13 cm long with crispate margins, the apices flat and not splitting when pressed; stipular sheaths 12-17 mm long, soon disintegrating into pale, persistent fibers; fruit 2.2-4.2 mm long, rarely keeled abaxially; peduncles 15-148 mm long; NOT [Leaf blades linear-lanceolate, (5) 10-25 (35) cm long with flat margins (rarely crispate), the apices prow-shaped and splitting when pressed; stipular sheaths 30-81 mm long, disintegrating into pale, persistent fibers with age; fruit 4-5.7 mm long, keeled abaxially; peduncles 95 -530 mm long]

Potamogeton: Answers to key questions in Rushes, Bulrushes & Pondweeds plus the remaining Monocots of Saskatchewan, Fascicle 6, Flora of Saskatchewan by Anna Leighton leading to this genus. 

Stipular sheaths of submersed leaves usually free from base of leaf, or if fused to leaf, then fused for less than half of the length of the sheath and leaf blades >= 3 mm wide; floating leaves present in some  species; blades of submersed leaves translucent, flattened, not channeled;  peduncles stiff and if long enough then projecting inflorescences above the water surface; NOT [Stipular sheaths of submersed leaves fused to base of leaf for two-thirds or more of the length of the sheath and leaf blades < 3 mm wide; floating leaves absent in all species; blades of submersed leaves opaque, channeled, turgid; peduncles flexible and not projecting inflorescences above the water surface]

Potamogetonaceae: Answers to key questions in Rushes, Bulrushes & Pondweeds plus the remaining Monocots of Saskatchewan, Fascicle 6, Flora of Saskatchewan by Anna Leighton leading to this family. 

	Plants larger and with well-defined stems and/or leave; NOT [Plants free-floating aquatics growing on the surface or suspended in water, solitary and 0.5-15 mm across or attached together in larger colonies; identifiable stems and leaves absent]
	Plants growing in water (aquatic) with stems, leaves and inflorescences growing underwater (submersed) or floating on the surface, sometimes with inflorescences somewhat elevated above the water (emergent); all leaves cauline, none basal; NOT [Plants growing on land (terrestrial) or in wetlands (paludal) with upper parts of stems, leaves and inflorescences growing well above the water surface (emergent), or if plants aquatic and submersed, then all or at least some leaves basal]
	Flowers and fruit not as below, either female flowers solitary in leaf axils have solitary fruit, or the flowers are perfect and 2-many in terminal or axillary spikes; blades various; NOT [Female flowers solitary in leaf axils with 4-5, short-stalked, beaked fruit with dentate convex margins; leaf blades linear, 0.2-1 mm wide, 3.5-4.2 cm long]
	Flowers 2 or more in terminal or axillary spikes; leaves submersed or floating, sessile or petiolate, often > 3 cm long, usually alternate with the pair under inflorescences nearly opposite; stipules forming sheaths enveloping stems, but often breaking down with age; NOT [Flowers and fruit solitary in leaf axils at stem nodes; leaves submersed, sessile, 0.5-3 cm long, opposite or whorled; stipules absent]
	Fruit sessile on spikes at maturity; spikes several- to many-flowered, exserted beyond sheathing leaf bases at anthesis; peduncles not coiling at base; pistils without stipes; tepals 4, attached to stamens; stipular sheaths usually unattached to leaf bases, if fused, then the free tips (ligules) 2-20 mm long (absent or obscure in Stuckenia vaginata);  floating leaves present in some species; NOT [Fruit borne on stipes up to 35 mm long in umbellate clusters at the tip of peduncles at maturity; spikes 2-flowered, enclosed within inflated leaf sheaths at anthesis; peduncles in some species coiling basally after fertilization; pistils stipitate, perianth absent; stipular sheaths fused to leaf bases for their full length with free tips (ligules) minute or lacking; floating leaves absent]