Nuphar japonica, known as East Asian yellow water-lily, is a perennial, aquatic, rhizomatous, herb in the family Nymphaeaceae native to Japan, Korea, and Russia.
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.
Nuphar japonica is a perennial, aquatic, rhizomatous, herb with 1âÂÂ3 cm thick rhizomes. The leaves are submerged, floating, or emerged. The leaf blade is 12âÂÂ35 cm long, and 6âÂÂ18 cm wide. The terete petiole is 3âÂÂ10(âÂÂ14) mm wide.
The yellow to red, solitary, 4âÂÂ5 cm wide flowers have a long, cylindrical peduncle. The flowers have five sepals and 10âÂÂ18 petals. The gynoecium consists of 15âÂÂ16 carpels. The 2âÂÂ3.5 cm long, and 1.6âÂÂ2.3 cm wide, urceolate, green, long-necked fruit bears ovoid seeds.
The chromosome count is 2n = 34.
It was published by Augustin Pyramus de Candolle in 1821. It is placed in the section Nuphar sect. Nuphar.
Nuphar ÃÂ saijoensis <small>(Shimoda) Padgett</small> is a natural hybrid between Nuphar japonica and Nuphar pumila.
The specific epithet japonica means of Japan.
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.
It occurs in lakes, ponds, and streams.
It is grown as an ornamental plant in aquaria, as well as in ponds.