European Water Chestnut
European Water Chestnut is an invasive aquatic plant native to Europe, Asia and Africa. Imported as an ornamental water garden plant, it was first observed in North America near Concord, Massachusetts in 1859. Since its arrival in North America, it has become a serious nuisance by forming dense mats of floating vegetation that shade out native vegetation, decrease plant biodiversity and seriously affect swimming, angling and boating in affected areas. The hard nuts have barbed spines which may cause injury when stepped on.
The European Water Chestnut is an annual plant that reproduces by vegetative means and seeds, which remain viable for up to 12 years. Containing hundreds of seeds, the nuts sink to the water bottom where the seeds germinate in the spring. One acre of water chestnuts can produce enough seeds to expand to 100 acres the next year. European Water Chestnut plants may be spread by re-rooting of leaf pieces and distribution of nuts downstream when individual plants are uprooted. Due to the size and weight of the nuts, it is unlikely they are spread by waterfowl or water currents.
Because the plant is an annual, control methods focus on removing the plant before it blooms and spreads seeds. Plants are pulled out and disposed of far away from water. Destroying one plant will prevent up to 120 plants from growing next year.
European Water Chestnut is established in the northeastern United States, with isolated populations in southern Quebec and on the Ottawa River within Voyageur Provincial Park.
How can you help?