The aquatic plantain is a species with an almost cosmopolitan distribution, present in all regions of Italy, but now in decline because of the reclamation of wet areas. It grows in marshy areas (margins of ponds, ditches, etc.), on muddy, perennially or at least periodically inundated soils with stagnant or very slow-flowing water, from sea level to the montane belt. In the temporary ponds of Sardinia the species was found only in the pond of Paule Longa (Ghilarza). Fresh leaves and rhizomes are poisonous. The genus name was the Greek-Latin name of an aquatic plant; the species name reefers to the leaves, which are vaguely similar to those of some Plantago. Flowering period: May to August.

Italian name(s): Alisma piantaggine-acquatica (Italia), Alismante (Toscana), Alismate (Toscana), Alismo (Toscana), Barba silvana (Toscana, Val di Chiana), Cavolaccio (Toscana), Centunervi d'acqua (Sicilia), Cinquenella d'acqua (Abruzzi, Larino), Cinquenerve (Campania, Napoli), Cinquenervi d'acqua (Campania, Napoli), Cinquenervi d'acqua (Italia), Cougè (Piemonte), Cucchiaio (Italia), Cucciar (Piemonte, Vercelli), Erba silvana (Toscana), Fistola di pastore (Toscana, Pisa), Lanzafina (Sicilia), Mestola (Toscana), Mestolaccia (Toscana), Mestolaccia comune (Italia), Mestolassa (Lombardia, Brescia), Mestole (Lombardia, Brescia), Petacciola aquatica (Toscana), Piantageno d'acqua (Veneto, Verona), Piantaggine aquatica (Toscana), Piantana de foss (Lombardia, Brescia), Piantassòn (Piemonte, Agliano), Piantazna d'acqua (Emilia-Romagna, Romagna), Plantassoun d'eva (Piemonte), Scuglieri (Veneto, Venezia), Sinquerigliu (Liguria, Mortola).