is one of the easiest western US plant species to identify, especially when in bloom. The distinctive yellow flowers are up to 4 inches in diameter, formed of between 7 to 9 (occasionally up to 12) overlapping sepals, forming a cup-shape, enclosing a yellow, disc-shaped stigma up to 1.5 inches across ringed by numerous red-purple stamens, beneath which, largely hidden, are between 10 and 20 small petals. The sepals have a waxy surface texture, and may be tinged with red or green towards the base.
This is an aquatic species, growing in still or slow-moving water; the petals are held at or slightly above the surface, while the leathery leaves are floating. The leaves are heart-shaped, with two backwards projections (lobes) at the base. The leaf stalk is usually much longer then the blade. Plants grow from large rhizomes, up to 15 feet long.