1	"Plants floating aquatics"	2
1	"Plants terrestrial"	4
2	"Plants stemless but with a rosette of sessile leaves to 14 cm long; roots feathery, many per plant"	"Pistia {Pistia stratiotes}"
2	"Plants 1-6 mm long, not differentiated into leaves and stems; roots simple, 0-several per plant"	3
3	"Roots present, 1 per frond"	"Lemna {Lemna aequinoctialis}"
3	"Roots absent"	"Wolffiella {Wolffiella hyalina}"
4	"Leaf blades simple; spadices without a sterile appendage"	Stylochaeton
4	"Leaf blades compound or deeply divided; spadices with a sterile, terminal appendage"	5
5	"Leaf blades basically 3-parted, each part further divided; spathes 15-33 cm long"	Amorphophallus
5	"Leaf blades pedately to radiately divided to the base, the leaflets sometimes divided into 2; spathes 3.5-15 cm long"	Arisaema