Photos: Rinecaha, the Burren
Very small flowers with four perianth segments and stamens. Separate carpels ripening to small nutlets. Narrow submerged leaves. Floating leaves are oval to elliptical-lanceolate, +/- translucent with clearly visible cross-veins.
Occurs in shallow water in calcareous fens and peaty ditches. Most frequent in central Ireland.
Similar: Bog Pondweed, P. polygonifolius
Fen Pondweed, Potamogeton coloratus. The Burren, July 2009