1	"Pistillate flowers +- sessile; scape bent at inflorescence"	"Sagittaria rigida"
1	"Pistillate flowers pedicelled; scape straight at inflorescence"	2
2	"Stolons, tubers 0; lowest inflorescence node with 2 bisexual flowers"	"Sagittaria montevidensis subsp. calycina"
2	"Stolons, tubers present; lowest inflorescence node with 3 pistillate flowers"	3
3	"Emergent leaf blades linear to lanceolate; pedicels recurved in fruit, thickened"	"Sagittaria sanfordii"
3	"Emergent leaf blades generally sagittate; pedicels ascending in fruit, not thickened"	4
4	"Basal lobes of emergent leaf blades generally > terminal; tubers spheric, tan"	"Sagittaria longiloba"
4	"Basal lobes of emergent leaf blades <= terminal; tubers oblong, +- white or +- blue"	5
5	"Fruit beak terminal, erect, 0.1--0.4 mm; emergent leaves with petioles recurved, basal lobes of blades < terminal"	"Sagittaria cuneata"
5	"Fruit beak lateral, spreading, 1--2 mm; emergent leaves with petioles ascending to erect, basal lobes of blades +- = terminal"	"Sagittaria latifolia"