any freshwater plant of the genus Sagittaria, consisting of about 20 species distributed worldwide, having leaves resembling arrowpoints. Arrowhead is a perennial herb with fleshy, or tuberous, roots that grows in shallow lakes, ponds, and streams. The flowers have three rounded petals. The tubers of some North American species were eaten by Indians and were known to early settlers as duck, or swan, potatoes. The most common species in North America is the broad-leaved arrowhead (S. latifolia), introduced by man to improve feeding areas for birds. Leaves of this species vary from arrow-shaped to grasslike. The grass-leaved arrowhead (S. graminea) is found throughout eastern North America. S. sagittifolia, which grows in most of Europe, is cultivated in China for its edible tubers.