2011-07-10 Lower Austria, district Bruck/Leitha - Reisenbach (165 msm Quadrant 7965/4).German name: Knoten-LaichkrautThere might be 2 Potamogeton-species in this shot here; those with 'netlike' nerves on the leaves definitely are P. fluitans; I think the other ones too are but they could be from another Potamogeton species growing in the same place.