Midwestern Arrowhead (Duck Potato; Wapato)
Aquatic perennial herb growing on muddy banks. Flowers erect, in mostly unbranched whorls of 3 (sometimes 2) on the flowering stalk. The flowers on the lowest 1-6 whorls are female, not showy, with many pistils, and bear green, rounded, burlike clusters of fruits, which turn brown in the fall. Flowers higher on the stalks are male, showy, with 3 white petals and many yellow stamens. Blooms June–September. Leaves basal. Leaf blades arrowhead-shaped or halberd-shaped, on long petioles that are often inflated, angled, or ribbed.
Similar species: Seven species of arrowheads are recorded for Missouri. This species can be distinguished by its large leaf blades, and the bracts at the base of each whorl of flowers, which are ¾–2½ inches long, linear to lanceolate, with a narrowly acute tip. Also, the female flowers are on stalks ½–1½ inches long.