Nuphar × spenneriana

Nuphar × spenneriana is a species of rhizomatous aquatic plant native to Europe. It is a natural hybrid of Nuphar lutea and Nuphar pumila.

Vegetative characteristics
Nuphar × spenneriana is a perennial, rhizomatous, aquatic plant. The abaxial leaf surface has trichomes towards the leaf margin. The leaf has 15-22 primary nerves.

Generative characteristics
The androecium consists of 60-100 stamens. The stigmatic disc has 9-15 rays.

Generative reproduction
It is fertile, but the pollen may be less viable. Pollen fertility can reach 73%. However, it can also be as low as 14% in F1 hybrids. In another case, a female sterility rate of 80%, and a male sterility rate of 85% have been reported. The seeds grow more rapidly than those of the parent species.

Publication
It was first described by Jean François Aimé Théophile Philippe Gaudin in 1828.

Natural hybridisation
It likely arose 10 000 years ago, when both parent species came into contact. Natural hybridisation is a threat to Nuphar pumila, one of the parent species, as the hybrid replaces populations of Nuphar pumila. In Eastern Europe and Asia observations of intermediate plants are rare. In Western Europe hybridisation appears to have played a more significant role.

Etymology
The nothospecific epithet spenneriana honours Fridolin Carl Leopold Spenner (1798-1841).

Habitat
It occurs in rivers, lakes, streams, and pools.