Also known as Flowering Rush.
The Greek generic name is alluding to the shape of the leaves likening them to the sword they used in ancient Greece for butchering cattle.
Grass Rush is a perennial aquatic plant growing at the margins of lakes and slow moving waters down to a depth of about 3 m.
Widespread in Eurasia and the roots are used as human food in Russia. It was introduced into the New World, where Butomus_umbellatus became a serious pest, invading for example the Great Lakes area in the US.