The native water lily, Nymphaea odorata, looks much like this. It’s known for its fragrance, if you can get close enough to sniff. Leaves usually float on the water surface or just beneath, but can be elevated somewhat when water levels are low. However, leaves are purple underneath, so, no, this beauty is not native. There is a native subspecies with green undersides, but its stems are striped. Apparently the frogs don’t care.