| In Britain the family Potamoganaceae (the Pond weed family) are dicotyledons, with a reduced preianth.
Leaves either opposite or alternate Inflorescence in stalked spikes; Flowers with 4 perianth segments Stamens 4 Genera eg. Groenlandia, Potamogeton |
| Potamogeton | Leaf margin | Petiole | ||
| toothed | entire | hinged | not hinged | |
| P. crispus | X | X | ||
| P. natans | X | X | ||
| P. polygonifolius | X | X | ||
