1	Fronds submersed (except when flowering or fruiting), often forming branched chains, at base narrowed into green stalk, margin denticulate distally.		1 L. trisulca
+	Fronds floating upon water surface, solitary or forming small groups, rounded at base, without green stalk, margin entire		(2)
2 (2)	Frond with 1 vein		L. minuta
+	Frond with 3-5 veins		(3)
3 (2)	Root sheath winged at base; root shorter than 3 cm; fronds without reddish color.		5 L. aequinoctialis
+	Root sheath not winged at base; root 0.5-15(-19) cm; fronds sometimes reddish, deep red, or with reddish spots on lower or upper surface		(4)
4 (3)	Plants often with small, olive-brown, rootless turions, which sink to bottom.		2 L. turionifera
+	Plants without distinct turions		(5)
5 (4)	Fronds with mostly distinct papillae on midline of upper surface; greatest distance between lateral veins near or distal to middle.		2 L. turionifera
+	Fronds with distinct papillae only above node and apex; greatest distance between lateral veins near or proximal to middle		(6)
6 (5)	Fronds often reddish or red on lower surface (more intensely so than on upper), flat or slightly gibbous.		3 L. japonica
+	Fronds always green on lower surface, sometimes reddish on upper surface, flat.		4 L. minor