Potamogeton natans
Systematics :
Kingdom: Plantae
Artificial group: Vascular plant (Tracheophytes)
Superphylum: Spermatophyte
Phylum: Magnoliophyta
Class: Liliopsida
Family: Potamogetonaceae
Genus: Potamogeton
Species: Potamogeton natans
Other names: vanleg tjønnaks, vanlig tjønnaks
Norwegian name: Tjernaks