The starchy corms (potato-like “tubers”) of some arrowhead species have been baked, roasted, boiled, and even candied. Different species may produce corms of different sizes. Large-leaved species might develop larger corms than species with smaller leaves.
Native Americans valued the arrowhead species for food, drying the corms to eat in winter.
To harvest the corms, you can't just yank on the plant stalk; it tends to just break off. Historically, Native Americans waded into the water and used their feet to squish around in the muck with their toes, and release the corms, which float up to the surface. You could try using a rake. The corms are not positioned directly below where the plants are emerging from the water. They develop in a circle in the muck, at varying depths, around where the plants appear to be.
Most people report that uncooked duck potatoes, though edible, are not very tasty. Boiling or roasting them for about half an hour seems to be the trick. Remove the stalk, first, and then peel them after cooking.
The young stalks, tender, uncurling leaves, and tender flower stalks (before they bloom) may be cooked as greens.
The leaves of many arrowhead species typically have arrowhead-shaped leaves. The genus name, Sagittaria, refers to these sagittate leaves and shares its Latin linguistic root with the constellation Sagittarius, the archer.
Some Sagittaria species are commercially important as aquarium plants or aquatic ornamentals.