Sagittaria sagittifolia (also called arrowhead due to the shape of its leaves) is a flowering plant in the family Alismataceae, native to wetlands most of Europe from Ireland and Portugal to Finland and Bulgaria, and in Russia, Ukraine, Siberia, Japan, Turkey, China, Australia, Vietnam and the Caucasus. It is also cultivated as a food crop in some other countries. In Britain it is the only native Sagittaria. (Wikipedia)

Sagittaria graminea, the grassy arrowhead or grass-leaved arrowhead, is an aquatic plant species native to eastern North America. It is known from every Canadian province from Ontario to Newfoundland, and every US state from the Great Plains to the Atlantic, plus Colorado, New Mexico and Cuba. It is considered naturalized in Washington State and in Vietnam. (Wikipedia)