Also known as Sagittaria sagittifolia. It is a flowering plant that is native to the wetlands of Europe and Asia. The leaves are arrow-shaped and the flowers generally have three white petals with numerous purple stamens.
Nicholson, George The Illustrated Dictionary of Gardening, Div. VI (London, England: L. Upcott Gill, 1884)
Courtesy the private collection of Roy Winkelman