1	"Inflorescence near ground, << subtending leaves; anthers << 1 mm"	"Hydrophyllum alpestre"
1	"Inflorescence well above ground, generally >= subtending leaves; anthers 1--2 mm"	2
2	"Leaf wide-ovate to round; leaflets generally 3--5"	"Hydrophyllum tenuipes"
2	"Leaf +- oblong; leaflets 7--15"	3
3	"Leaflets acute to acuminate, teeth generally 4--8 per side"	"Hydrophyllum fendleri var. albifrons"
3	"Leaflets obtuse to acute, teeth generally 2--4 per side"	"Hydrophyllum occidentale"