White Water Lily
Due to its attractiveness, this nonnative plant has been introduced to many lakes in Washington. The white water lily is a perennial plant that often form dense colonies causing water quality problems and preventing many recreational activities. The leaves arise on flexible stalks from large thick rhizomes.
The white waterlily can grow to nuisance densities and, in response to high nutrient availability, accelerate nutrient over-enrichment of a water body that can contribute to blue green algae blooms.
The white water lily leaves are more round than heart-shaped, bright green, 6 to 12 inches in diameter with the slit about 1/3 the length of the leaf. Leaves usually float on the water’s surface. Flowers arise on separate stalks, have brilliant white petals (25 or more per flower) with yellow centers. The flowers may float or stick above the water and each opens in the morning and closes in the afternoon. The flowers are very fragrant. White water lily can spread from seeds or the rhizomes.
The most common and effective eradication treatment is a systemic chemical called Glyphosate that is applied directly to the petals which kills the entire plant. Harvesting of the dead plant is most preferrable as the left over rhizomes can detach and float on the surface of the lake.