Nuphar × fluminalis

Nuphar × fluminalis is a species of rhizomatous aquatic plant endemic to Japan. It is a natural hybrid of Nuphar japonica and Nuphar submersa.

Vegetative characteristics
Nuphar × fluminalis is has an intermediate appearance and falls between Nuphar japonica and Nuphar submersa. The submerged leaves are ovate.

Generative characteristics
The filaments are recurved. The anthers display orange-red colouration. The stigmatic disk, as well as the fruit, also display orange-red colouration.

Generative reproduction
Sexual reproduction occurs within this hybrid.

Publication
It was first described by Takashi Shiga and Yasuro Kadono in 2007.

Etymology
The nothospecific epithet fluminalis, from the Latin fluminalis, means stream or river.

Conservation
It is critically endangered. Only four populations are known.

Habitat
It occurs in streams and rivers.