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Washington State Department of Ecology > Water & shorelines > Freshwater studies > Lake water quality > Aquatic Plant Guide home > Floating Leaved Rooted Plants > Nuphar polysepala

Aquatic Plant Identification Manual for Washington's Freshwater Plants

Floating Leaved Rooted Plants

Species: Nuphar polysepala Engelm; Snyonym Nuphar lutea subsp. polysepala, spatterdock, yellow cow-lily, yellow pond-lily
Family: Nymphaecaceae

Spatterdock is a perennial waterlily-like plant that can form extensive stands in the shallow waters of lakes and ponds. When mature, spatterdock has large elephant-ear-shaped leaves and yellow flowers. Unlike the showy, many-petaled fragrant waterlily flowers, spatterdock blossoms are simple yellow globes that partially open to reveal reddish poppy-like centers. The leaves and flowers float on, or stand above the water, on thick, fleshy stalks.

Leaf: Large, (10-45cm long and 7-30 cm wide) green, heart-shaped leaves have a notched base, blunt tip, prominent midvein, and leathery surface. They rise directly from the rhizome and float on or extend above the water. In early summer, spatterdock has large, delicate underwater leaves that resemble lettuce or cabbage leaves.

Stem: Flower and leaf stalks arise directly from the rhizome. The green "stems" are actually leaf and flower stalks.

Flower: Waxy and greenish-yellow globes (5-10 cm across) open to form bright yellow cup-shaped flowers that rise above the water. The 9 (8-17) yellow "petals" are actually sepals. The stamens are reddish. The flowers have a sweet fragrance on the first day the flower is open, but after that the odor is less pleasant. Blooms May to August.

Fruit: One urn-shaped fruit develops from each flower and contains numerous brown seeds. (3-5mm long).

Root: Fibrous roots anchor the massive, scaly, log-like rhizomes to the sediment. The rhizomes are up to 20 cm in diameter and 5 m long.

Propagation: Rhizomes, seeds.

Importance of plant: Spatterdock is a food source for mammals and waterfowl and provides spawning habitat for fish. Native Americans used the rhizomes and seeds for food. Used by several cultures for food, dyeing, tanning, and medicinal purposes.

Distribution: Western North America.

Habitat: Shallow lakes and ponds, sluggish streams, and canals.  

May be confused with: White waterlily (Nymphaea odorata) which has cleft rounded leaves and showy, many-petaled white or pink flowers. Watershield (Brasenia schreberi), which has small, Native American Use Icon oval leaves with a jelly-like coating on the undersides and inconspicuous purplish flowers. Nupahr variegatum, which has yellow stamens, 6-8 sepals, and a flattened leaf stalk.

Photographs: Nuphar polysepala floating leaves, Nuphar polysepala closeup of flowers and leaves
Line Drawings: Nuphar polysepala

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