1	"Sepals, petals 4; stamens 8; pedicels elongating in fruit to 2--3 × fruit; seeds curved 90--180°"	"Elatine californica"
1	"Sepals 2--3, petals 3; stamens (1) 3, 6; pedicels generally +- 0, occasionally +- elongating in fruit to <= 1/2 fruit; seeds straight or curved <= 30&deg;"	2
2	"Flower subsessile to stalked, +- erect; fruit pedicel turned to 1 side; sepals 3, +- equal"	"Elatine ambigua"
2	"Flower sessile, erect; fruit pedicel not turned to 1 side; sepals 2, +- equal, or 3, 1 < others"	3
3	"Stamens (1) 6 (if 3, opposite petals)"	"Elatine heterandra"
3	"Stamens 3, alternate petals"	4
4	"Seed pits 10--15 per row"	"Elatine brachysperma"
4	"Seed pits 16--35 per row"	5
5	"Seed pits wider than long"	"Elatine chilensis"
5	"Seed pits +- as wide as long"	"Elatine rubella"