As an aquatic plant with leaves that rest on the water's surface, the genus Nelumbo is characterized by its concentration of stomata on the upper epidermis of its leaves, unlike most other plants which concentrate their stomata on the lower epidermis, underneath the leaf.

[6] An uncommon property of the genus Nelumbo is that it can generate heat,[7] which it does by using the alternative oxidase pathway (AOX).

The pathway used to generate heat in Nelumbo involves cyanide-resistant alternative oxidase, which is a different electron acceptor than the usual cytochrome complexes.

[14] After anthesis, the receptacle of the lotus transitions from a primarily thermogenic to a photosynthetic structure, as seen in the rapid and dramatic increase in photosystems, photosynthetically involved pigments, electron transport rates, and the presence of 13C in the receptacle and petals, all of which assist in increasing photosynthesis rates.

Pollinators do not need to be attracted once the ovary is fertilized, and thus the receptacle's resources are better used when it is photosynthesizing to produce carbohydrates that can increase plant biomass or fruit mass.

Among these is the eastern skunk cabbage, which heats itself to melt any ice above it, and push through the ground in early spring.

In addition, the carrion flower, which heats itself to disperse water vapor through the air, carrying its scent further, thus attracting more pollinators.

The Cronquist system of 1981 recognizes the family Nelumbonaceae but places it in the water lily order Nymphaeales.

The United States Department of Agriculture still classifies the lotus family within the water lily order.

Nelumbo is currently recognized as the only living genus in Nelumbonaceae, one of several distinctive families in the eudicot order of the Proteales.

[18] There are several fossil species known from Cretaceous, Paleogene and Neogene aged strata throughout Eurasia and North America.

Despite the ancient origins of this genus and the wide geographic separation of the two extant species (N. nucifera and N. lutea), phylogenetic evidence indicates that they diverged rather recently, during the early Pleistocene (about 2 million years ago).