Spatterdock (Cowlily, Yellow Pond Lily, Yellow Water Lily)

Nuphar advena (formerly N. lutea)
Nymphaeaceae (water lilies)

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.

Leaf length and width: 2–16 inches.
Habitat and conservation: 
Margins of ponds, lakes, slow-moving to stagnant portions of streams, rivers, and spring branches, sloughs, and fens.
Distribution in Missouri: 
Scattered along and south of Missouri River.
Botanists used to consider our spatterdock the same species as one found in Eurasia (N. lutea), but DNA testing has shown they are not so closely related. That’s why our species is now called N. advena. There are two subspecies in Missouri: ssp. advena, with green or yellowish sepals and flowers ¾ to 2 inches wide, and ssp. ozarkana, with reddish- or purplish-tinged sepals and flowers ½ to 1 inch wide. Ssp. ozarkana is more common in Missouri, often seen in spring-fed Ozark streams and rivers.
Human connections: 
The starchy roots were eaten by Native Americans, as were the seeds.
Ecosystem connections: 
Pollinators include bees, flies, and beetles. Interestingly, when the flowers close in the evening, they sometimes trap beetles in the flower overnight, releasing them when they reopen the next morning. The seeds are consumed by deer, muskrat, beaver, raccoons, and waterfowl.
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