Alisma plantago-aquatica

Alisma plantago-aquatica, also known as European water-plantain, common water-plantain or mad-dog weed, is a perennial flowering aquatic plant widespread across most of Europe and Asia from Portugal and Morocco to Japan, Kamchatka and Vietnam. It is also regarded as native in northern and central Africa as far south as Tanzania. It is reportedly naturalized in southern Africa, Australia, New Zealand, Alaska, British Columbia, Washington state and Connecticut.[2][3][4] Some sources maintain that the species is widespread across North America, but these reports appear to have been based on misidentified specimens.[5] It is found on mud or in fresh waters.

Alisma plantago-aquatica is a hairless plant that grows in shallow water, consists of a fibrous root, several basal long stemmed leaves 15–30 cm long, and a triangular stem up to 1 m tall. It has branched inflorescence bearing numerous small flowers, 1 cm across, with three round or slightly jagged, white or pale purple petals. The flowers open in the afternoon. There are 3 blunt green sepals, and 6 stamens per flower. The carpels often exist as a flat single whorl. It flowers from June until August.[6]

The word alisma is said to be a word of Celtic origin meaning “water”, a reference to the habitat in which it grows. Early botanists named it after the Plantago because of the similarity of their leaves.[7]