Fragrant water lilies (Nymphaea odorata) are exceptionally beautiful water plants with floating leaves and large many-petaled fragrant blossoms. They are wonderful additions to backyard ponds and even "tub gardens." The nursery industry has hybridized them and produced many color variations. They sell tropical water lilies and hardy water lilies. It is the hardy white and (sometimes) pink lilies that have become naturalized in Washington lakes and rivers. These plants are native to the eastern United States and it is believed that the water lily was introduced to Washington during the Alaska Pacific Yukon Exposition held in Seattle in the late 1800s. Because of their great beauty, water lilies have been intentionally planted in many Washington lakes, especially those lakes in western Washington. However, lake residents are strongly discouraged from planting fragrant water lilies in lakes or natural waterbodies. Not only are water lilies aggressive plants, but sometimes "hitchhiker" plants such as hydrilla can also be introduced to our lakes when water lilies are planted.
Water lilies grow in dense patches, excluding native species and even creating stagnant areas with low oxygen levels underneath the floating mats. These mats make it difficult to fish, water ski, swim, or even paddle a canoe through. Although relatively slow-spreading, water lilies will eventually colonize shallow water depths to six feet deep and can dominate the shorelines of shallow lakes. For this reason, planting water lilies in lakes is not recommended. Water lilies reproduce by seed and also by new plants sprouting from the large spreading roots (underground stems called rhizomes). A planted rhizome will cover about a 15-foot diameter in about five years.
Fragrant water lily has an interesting pollination strategy. Each white or pink flower has many petals surrounding both male and female reproductive parts, and is only open during the daytime for three days. On the first morning, the flowers produce a fluid in the cup-like center and are receptive to pollen from other flowers. However, they are not yet releasing pollen themselves. Pollen-covered insects are attracted by the sweet smell, but the flower is designed so that when they enter the flower, they fall into the fluid. This washes the pollen off their bodies and onto the female flower parts (stigmas) causing fertilization. Usually the insects manage to crawl out of the fluid and live to visit other flowers, but occasionally the unfortunate creature will remain trapped and die when the flower closes during the afternoon. On the second and the third days, the flowers are no longer receptive to pollen, and no fluid is produced. Instead, pollen is released from the stamens (the flexible yellow match-shaped structures in the flower center). Visiting insects pick up the pollen and transport it to flowers in the first day of the flowering cycle. After the three days the flowers are brought under water by coiling their stalks. The seeds mature under water and after several weeks are released into the water. Water currents or ducks, which eat the seeds, distribute them to other areas. This flowering regimen is followed nearly throughout the summer, producing many eye-pleasing blooms and a large supply of seeds.
In addition to reproducing by seeds, water lilies spread by rhizomes. Anyone who has tried to curtail this plant's growth in front of their dock knows how tenacious these root systems are. Also, if pieces of the rhizome are broken off during control efforts, they will drift to other locations and establish a new patch of lilies.
The fragrant water lily was utilized in many ways by Native Americans in the eastern United States. Roots of this and other water lilies were used medicinally as a poultice for sores and tumors, internally for many aliments including digestive problems, and rinse made for sores in the mouth. The leaves and flowers were also used as cooling compresses. In addition, the rhizomes were occasionally used as food and the young leaves and lower buds were eaten as a vegetable. Even the seeds were fried and eaten or ground into flour. Wildlife, including beaver, muskrat, ducks, porcupine, and deer also will eat the leaves, roots, or seeds. In moderate quantities the fragrant water lily can also benefit the lake by providing shelter and habitat for fish and invertebrates and shade to cool the water. However, our native water lilies, like spatterdock (Nuphar polysepalum) and watershield (Brasenia schreberi), will also provide the same benefits as the fragrant water lily and are not invasive.
Water lilies can be controlled by cutting, harvesting, covering with bottom barrier materials, and aquatic herbicides (Rodeo®. Grass carp will not eat these plants. Lake residents have indicated that extremely persistent "picking" of emerging water lilies leaves every other day during the growing season for two to three seasons will eventually kill the plants. When water lilies are killed by herbicides or other means, the dead and decomposing roots (rhizomes) will sometimes form floating mats in the lake or waterbody.
Because of their large, showy flowers, water lilies are easy to identify when flowering. They have white or pink showy flowers. When not in flower look for:
Spatterdock (also called yellow pond or cow lily) has a yellow "ball-shaped" flower and large elephant-ear-shaped leaves that often stick up above the surface of the water. Watershield has small floating leaves with the underside often coated in a gelatinous slime and inconspicuous purple flowers.
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