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Pistia stratiotes
Water-lettuce
Not native to Florida
This plant is an invasive exotic that is altering native plant communities by displacing native species, changing community structures or ecological functions, or hybridizing with natives.
This species should never be planted (many with this designation are prohibited by law), and generally should be removed whenever possible.
This floating plant is common in ponds, sloughs, river and canals thoughout peninsular Florida and several panhandle counties. In North America water lettuce is found in most coastal southeastern and mid-Atlantic states, plus Ohio, Missouri, Colorado, Arizona, California and Hawaii. The worldwide range includes most of the equatorial regions, plus much of South America and nearly all of Africa excluding the desert regions.
William Bartram saw extensive populations of water lettuce in 1765 which he described as floating islands on the St. Johns River. Paleo-botanical (fossil) evidence suggests that this species has existed on the Florida peninsula for thousands of years and was not introduced by the early Spanish explorers and inhabitants as has been widely accepted. For more information on this theory, read Pistia stratiotes L. in the Florida Peninsula: Biogeographic Evidence and Conservation Implications of Native Tenure for an 'Invasive' Aquatic Plant.
Pistia stratiotes is a free-floating roseate of light green leaves that are hairy and ridged. Flowers are inconspicuous on a short stalk with a whorl of male flowers above a single female flower. Numerous light-colored feathery roots hang beneath the leaves.
For more information on water lettuce in Florida, visit the Center for Aquatic and Invasive Plants page for this species
Pistia stratiotes is a member of the Araceae - Arum family.
Atlas of Florida Vascular Plants (Institute for Systemic Botany) profile for this species
USDA Plant Profile for this species
Date record last modified: Aug 07, 2016
