Family: Araceae (Arum Family)
Duration and Habit: Perennial Herb
Water lettuce is very easy to identify: it resembles a floating open head of lettuce and may be found singly or in abundance; its light green leaves are thick, hairy and ridged; its flowers are not seen except by close examination.
Native Lookalikes: Currently no information available, or there are no native species that could be confused with Water lettuce.
Ecological Threat: Severe infestations block light to the water ecosystem, reduce oxygen levels, increase siltation, reduce suitable fish spawning habitat and restrict water flow and boating traffic.
Biology & Spread:
History: Water lettuce has an uncertain origin. There is a large amount of confusion surrounding the origin of water lettuce due to its heavy worldwide distribution. However, it is commonly believed that it is a native of South America or Africa. There is particularly strong evidence linking water lettuce to South America. South America is the location of many regionally native insects associated with water lettuce.
U.S. Habitat: Water lettuce invades lakes, ponds and slow moving streams in tropical, subtropical and warmer temperate regions.
U.S. Nativity: Introduced
Native Origin: South America to Africa
U.S. Present: AZ, CA, DE, FL, GA, HI, LA, MD, MS, NC, NJ, NY, PR, SC, TX, VI
Distribution: Florida west to Texas. Outside Native Range
List All Observations of Pistia stratiotes reported by Citizen Scientists
Contact herbicides such as Endothall and Diquat will act quickly, while systemic herbicides such as Rodeo act slowly. Take care to minimize impacts of herbicide application on native species. Decaying plant material may cause dissolved oxygen depletion.USE PESTICIDES WISELY: ALWAYS READ THE ENTIRE PESTICIDE LABEL CAREFULLY, FOLLOW ALL MIXING AND APPLICATION INSTRUCTIONS AND WEAR ALL RECOMMENDED PERSONAL PROTECTIVE GEAR AND CLOTHING. CONTACT YOUR STATE DEPARTMENT OF AGRICULTURE FOR ANY ADDITIONAL PESTICIDE USE REQUIREMENTS, RESTRICTIONS OR RECOMMENDATIONS. MENTION OF PESTICIDE PRODUCTS ON THIS WEB SITE DOES NOT CONSTITUTE ENDORSEMENT OF ANY MATERIAL.
Bugwood Network. 2010. Pistia stratiotes. Accessed 20 August 2010 (http://www.invasive.org/browse/subthumb.cfm?sub=3064).
Germplasm Resources Information Network
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Invasive Plant Atlas of the United States: Pistia stratiotes
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