Yellow water lily, spatterdock, cow lily

It's definitely confusing. USDA says N. lutea is the current correct name for N. advena, while the ufl site says N. advena is the current correct name for N. lutea. For no special reason, I go with the USDA nomenclature when I find such contradictions. I'll edit the spotting to include the common names spatterdock and cow lily.

Spatterdock is another common name for this plant (and other species in this genus). Aka yellow pond lily. According to the USDA, there is only one species in found in the US, Nuphar lutea; plants once considered separate species, e.g., N. polysepala (found in the western half of North America), are now classified as subspecies of N. lutea.