This grass with an originally Eurasian distribution has now become almost cosmopolitan, and is present in all regions of Italy except perhaps in Valle d'Aosta (since a long time no longer reported from Campania). It grows in marshes and reed beds along waterways, on silty-clay, flooded soils that are rather rich in bases, but sometimes poor in calcium, from sea level to the montane belt. The species is sporadic in the central belt of the Sardinian temporary ponds. The genus name derives from the Greek 'glykeros' (sweet), for the flavour of the seeds that were once used for human consumption, the species name refers to the fact that the leaves are sometimes submerged in running water. Flowering period: May to July.

Italian name(s): Fienarola d'acqua (Toscana), Gliceria fluitante (Italia), Grame d'aghe (Friuli), Gramigna olivella (Toscana), Gramignone natante (Italia), Manna di Polonia (Toscana), Manna di Prussia (Toscana).