Villarsia is the old name for Nymphoides. It is still recognized as a synonym.
It is also a family name. When they realized the North American ones that look the same as Old World varieties were actually different species, they started differentiating the family names.
Frogbit (Hydrocharis) is also similar, but it doesn't have the distinctive pistil.
It is also a family name. When they realized the North American ones that look the same as Old World varieties were actually different species, they started differentiating the family names.
Frogbit (Hydrocharis) is also similar, but it doesn't have the distinctive pistil.