The green floater (Lasmigona subviridis) is a species of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels.

This species is endemic to the United States.

It is found in West Virginia, Delaware, Maryland, Tennessee, North Carolina, Pennsylvania, New Jersey, Virginia and New York, and has been extirpated from Alabama and Georgia.

[1][2] Its populations in the Susquehanna River and the Potomac River are considered to be genetically distinct from the southern population.

[4] It is reported to be a simultaneous hermaphrodite under most conditions.