Spatterdock (Cowlily, Yellow Pond Lily, Yellow Water Lily)
Perennial, herbaceous, emergent aquatic. Flowers at or just above water surface, deep yellow, saucer- or globe-shaped, to 3 inches across; sepals usually 6, overlapping and much larger than the many petals, which are small, thick, oblong, and scalelike, in a ring just below the stamens. The many stamens surround a large, compound ovary. Blooms May–October. Leaves at or just above water surface, egg- to heart-shaped with a wide, basal V-notch, of variable size.
Similar species: Water lilies (Nymphaea spp.) have large, showy flowers with many petals that are typically white to pink to violet; the leaves are round, with a cleft. American lotus (Nelumbo lutea) has yellow to cream-colored flowers that open to 8 inches across with a large central disk that resembles a showerhead. The leaves do not have a cleft and are usually held above the water.