The biology of Canadian weeds. 103. Vallisneria americana Michx.

American wild celery (Vallisneria americana Michx.) is a native submerged aquatic plant that differs from other ribbon-leaved aquatics in having leaves with a well-defined midvein and paler zones on either side of a central dark band. In southern Ontario and Québec the dense leaf growth, and in particular the floating plants dislodged from the sediment, impede water traffic and restrict water-based recreation. Mechanical harvesting may be the best method of control in most situations. American wild celery is beneficial as an important food source for waterfowl and other wildlife, as cover and spawning area for fish, and may also be used as fertilizer and to feed livestock. There is also potential for increased use in biomonitoring. Widespread in eastern North America, it reaches its northern limit in southeastern Canada. It is introduced in British Columbia and the northwestern United States, and has also recently been reported from the southwestern United States, Mexico, the Carribean islands, northern Central America, southeast Asia and Australia. American wild celery occurs in alkaline to slightly saline waters with pH > 6, at depths of 0.3–7 m, and in a variety of sediment types. Clonal growth is extensive. Parent rosettes can each produce 20 or more new shoots within a season. These develop from buds at the tip of stolons, some of which overwinter as turions. Pollination takes place on the surface of the water with free-floating male flowers tipping into the surface depression created by the larger, attached female flowers. Fruits mature under the water.