This alliance includes aquatic vegetation dominated by various species of Potamogeton, and in some cases also of Elodea. Groenlandia. Myriophyllum. Najas and Zannichellia. Most of them have narrow submerged leaves or leaflets, although some have large entire leaves, which are either submerged or with blades floating on the water surface. Biomass produced by this vegetation type is smaller than that produced by the Nymphaeion albae vegetation, although quite often the dominant species occupies the entire water column. Dominant species of the Potamion communities have small inconspicuous flowers, either water-pollinated or emerging above the water surface and pollinated by wind.