Arrowhead is the common name for Sagittaria sagittifolia, a perennial herb with distinctive arrow-shaped leaves that grows in ponds, rice fields, and swamps across parts of Asia. Its starchy underground corms are eaten as a vegetable, harvested in autumn and boiled or roasted like potatoes; related species are cultivated as kuwai in Japan and cigu in China. As an aquatic crop it must be grown in clean water, since corms readily pick up heavy metals and microbial contaminants from polluted paddies. Like potatoes, the corms must always be cooked before eating, both for digestibility of the raw starch and as a basic food-safety precaution.