This species of water fennel with a Mediterranean-Atlantic distribution is present in Lombardy, Veneto, Trentino Alto Adige, and in all regions of Central, Southern and Insular Italy (since a long-time no longer found in Liguria). It grows near springs, along ditches and in swamps, from sea level to about 800 m. The species is rare in the outer belt of the Sardinian temporary ponds. The whole plant is poisonous, due to the presence of neuro- and enterotoxic active principles (oenanthetoxines). The genus name derives from the Greek 'oinos' (wine) and 'anthos' (flower), as when ingested in small doses the plant causes mental changes similar to drunkenness; the species name derives from Silaum, a genus of Apiacee, and it means 'with leaves similar to those of Silaum'. Flowering period: June to July.

Italian name(s): Finocchio acquatico silaifoglio (Italia).