The largest of the Glyceria species; it is reed-like in its tall erect habit. It forms dense beds at the margins of some lakes such as Lower Lough Erne, where it is abundant about Enniskillen district, and along the Quoile River near Downpatrick. Overall, however, it is rather rare and confined to a few localities, and it appears to have been deliberately planted as an ornamental in some artificial lakes and ponds.
All names: Glyceria maxima (Hartman) O.Holmb.; Glyceria aquatica (L.) Wahlb., non J. & C.Presl; Poa aquatica L.