Sagittaria: Answers to key questions leading to this genus. 

Emergent leaves mostly sagittate or hastate; inflorescences usually racemes with whorls of flowers, rarely panicles; pistils and achenes spirally arranged on convex receptacles, very numerous; flowers imperfect; stamens 7-30; NOT [Emergent leaves linear-lanceolate or elliptic to ovate; inflorescences panicles with whorls of branches; pistils and achenes arranged in a single ring around margin of flat receptacles, usually fewer than 20; flowers perfect; stamens few, 6-9]

Cuneata: Answers to key questions leading to this species (in genus Sagittaria). 

	Pistillate flowers distinctly pedicellate; fruiting pedicels 5-35 mm long; achene beaks if curved, then <0.8 mm long; filaments glabrous; NOT [Pistillate flowers sessile to subsessile; fruiting pedicels absent; achene beaks recurved, 0.8-1.4 mm long; filaments pubescent to tomentulose]
	Achene beaks either horizontal and 1-2 mm long, or erect and immeasurably short (<= 0.4 mm long); fruiting heads <= 17 mm wide (in our specimens < 15 mm wide); inflorescence bracts delicate to membranous; leaves emergent, floating or submersed; NOT [Achene beaks ascending apically, 0.4-1.7 mm long; fruiting heads (12) 15-25 mm wide; inflorescence bracts firm; leaves emergent]
	Achene beaks erect,  0.1-0.4 mm long; inflorescence bracts usually long and narrow (up to 40 mm long and lance-attenuate or acute); leaves emergent, floating or submersed with submersed leaves often linear with phyllodial petioles; NOT [Achene beaks horizontal,1-2 mm long; inflorescence bracts usually short and wide (3-8 (ours to 10) mm long and elliptic to lanceolate); leaves usually emergent]