Tufted aquatic perennial. When plant grows in water, flowers and leaves elongate to reach the surface. Leaves in basal groups on long sturdy stalks, bright green, ovate to oblong. Flowers bright yellow with 5 distinctive frilly-fringed petals borne on branched stems.

Fruit is a 4-division capsule.

After: Dominique Villars (1745-1814), French botanist and physician, professor of botany and medicine at the University of Strasbourg.