Dear
This one is really strange amalgamation of 2 aquatic species the leaves are that of Calla palustris (bog arum), I almost 100% sure given the leaf morphology and aquatic habit. The flower of this species is funnel like spathe, a constant of araceae family.
The flower attached is that of Sagittaria latifolia (Duck potato), but the arrow shaped leaves are no where to be seen. My guess is that the rhizome is buried under water and is flowering. It could be Echinodorus also.
As for Echinodorus cordifolius the leaf morphology of this South American Amazon species light green with striated throughout. Leaf is unlikely to be that of any Echinodorus.
Regards