Key for Eichhornia Kunth

1Plants floating; vegetative stem condensed; petioles commonly swollen.
1'Plants rooted; vegetative stem short or long; petioles never swollen.
2Vegetative stem short; leaves cordate and more than 6 cm long; inflorescences a panicle.
2'Vegetative stem elongate; leaves oblong or cordate and less than 4 cm long; inflorescence a spike.
3Leaf base cordate; inflorescence with 2-3 flowers; individual flowers less than 2 cm across.
3'Leaf base truncate to obtuse (very rarely subcordate); inflorescence with 4 or more flowers; individual flowers more than 2.5 cm across.
4Inflorescence moderately to densely pubescent; upper middle tepal with yellow spot; lower stamens 15-29 mm long.
4'Inflorescence glabrous or nearly so; upper middle tepal without yellow spot; lower stamens 11-15 mm long.