While all modern plant taxonomy systems agree that this species belongs in the genus Nelumbo, the systems disagree as to which family Nelumbo should be placed in, or whether the genus should belong in its own unique family and order.
The lotus is often confused with the water lilies (Nymphaea, in particular Nymphaea caerulea “blue lotus”). In fact, several older systems, such as the Bentham & Hooker system (which is widely used in the Indian subcontinent) call the lotusNymphaea nelumbo or Nymphaea stellata. This is, however, evolutionarily incorrect. Far from being in the same family,Nymphaea and Nelumbo are members of different orders (Nymphaeales and Proteales, respectively). Adding to the confusion, some sources have used the scientific name Nymphaea stellata for another species called Blue Lotus or nil mānel in Sinhalese, which is the national flower of both Sri Lanka and Bangladesh.
Thanks for (Senko)