Watershield is a perennial aquatic plant whose bright green, shield-shaped leaves float on the surface of shallow water in lakes and beaver ponds. Its small purple flowers bloom from June through September, with each individual flower only lasting two days. One the first day, the female flower parts (stigma, style, ovary) are mature. After receding into the water overnight, the flower re-emerges with mature male flower parts (stamens, filaments, anthers). The anthers burst open, releasing pollen to the wind, and the flower is then withdrawn below the water where the fruit develops.
The horizontal rhizomes, or stems, of Watershield, as well as the undersides of the leaves and developing buds, are covered with a thick, jelly-like slime. Botanists theorize that it may deter snails from grazing on these plants. Watershield secretes a number of chemicals that kill or inhibit growth of a wide range of bacteria, algae, and other plants.