Nuphar japonica

Nuphar japonica, known as East Asian yellow water-lily, is an aquatic plant species in the genus Nuphar found in Japan and the Korean Peninsula. It is endangered in Russia. The species was not accepted by The Plant List, which regarded it as an "unresolved name".

Nuphar japonica is one of three species in the genus Nuphar that is dispersed in the same geographical location of the Saijo Basin, an area in the Hiroshima Prefecture of Japan.

Natural hybrids
Nuphar × saijoensis (Shimoda) Padgett is a hybrid between N. japonica and N. pumila.

Phytochemistry
N. japonica contains the alkaloids nupharidin, 1-desoxynupharidin, nupharamine, methyl and ethyl esters of nupharamine. The fruits also contains the alkaloids (0.06%) nupharine, beta-nupharidin, desoxynupharidin. In the rhizomes are found the steroid sitosterol, alkaloids acids, higher fatty acids (palmitic, oleic acid) and the ellagitanins nupharin A, B, C, D, E and F.