water lettuce USDA PLANTS Symbol: PIST2
U.S. Nativity: Native
Habit: Aquatic Plants Forbs/Herbs
Pistia stratiotes L.

Jump to: Resources | Images | Distribution Maps | Sources
Taxonomic Rank: Liliopsida: Arales: Araceae
Synonym(s): tropical duckweed
Native Range: pantropical (GRIN);

Appearance
Pistia stratiotes is a sprawling, semi-woody shrub that invades wetlands in Florida. The green stems are up to 15 ft. (4.6 m) long and prickly.
Foliage
Leaves are flashy and arranged in a rosette. They measure 0.75-6 in. (2-15 cm) in length. The leaves are green to grayish-green, and have dense white hairs and parallel veins on their surface. As its common name indicates, the plant resembles a floating head of lettuce.
Flowers
This plant flowers year-round in southern Florida, but peaks during summer and early autumn.
Fruit
The hydrosoil under a Pistia stratiotes infestation was shown to hold 4,196 seeds/m2. Mature seeds in fruits had an 84% germination rate.
Ecological Threat
Pistia stratiotes, forms extensive mats that can block navigational channels, impede water flow in irrigation and flood control canals, and disrupt submersed animal and plant communities (Sculthorpe, 1967; Attionu, 1976; Bruner, 1982; Sharma, 1984). Pistia stratiotes is among the world’s worst weeds (Holm et al., 1977). It has been placed on prohibited plant lists in Florida (FDEP, 2000), Louisiana (LDWF, 2000), Mississippi (MDAC, 1997), and Texas (TPWD, 2000), and is considered a noxious species (an invasive species of concern, but not regulated) in South Carolina (SCDNR, 2000) and Delaware (DDFW, 2000).

Identification, Biology, Control and Management Resources

Selected Images from Invasive.orgView All Images at Invasive.org


Plant(s);
USDA Agricultural Research Service , USDA Agricultural Research Service, Bugwood.org
Additional Resolutions & Image Usage

Foliage;
Graves Lovell, Alabama Department of Conservation and Natural Resources, Bugwood.org
Additional Resolutions & Image Usage

Plant(s);
USDA APHIS PPQ - Oxford, North Carolina , USDA APHIS PPQ, Bugwood.org
Additional Resolutions & Image Usage

Plant(s);
USDA APHIS PPQ - Oxford, North Carolina , USDA APHIS PPQ, Bugwood.org
Additional Resolutions & Image Usage

Plant(s); exotic invasive
Troy Evans, Great Smoky Mountains National Park, Bugwood.org
Additional Resolutions & Image Usage

Plant(s); in water garden
Forest and Kim Starr, Starr Environmental, Bugwood.org
Additional Resolutions & Image Usage

Foliage; in water garden
Forest and Kim Starr, Starr Environmental, Bugwood.org
Additional Resolutions & Image Usage

Foliage; leaf
Forest and Kim Starr, Starr Environmental, Bugwood.org
Additional Resolutions & Image Usage

Plant(s);
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Additional Resolutions & Image Usage

Flower(s);
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Additional Resolutions & Image Usage

Plant(s);
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Additional Resolutions & Image Usage

Infestation;
Karen Brown, University of Florida, Bugwood.org
Additional Resolutions & Image Usage

Infestation;
Karen Brown, University of Florida, Bugwood.org
Additional Resolutions & Image Usage

Infestation;
USDA APHIS PPQ - Oxford, North Carolina , USDA APHIS PPQ, Bugwood.org
Additional Resolutions & Image Usage

Infestation; Ichetucknee Springs State Park, Columbia/Suwannee counties, Florida, U.S.A.
Richard Carter, Valdosta State University, Bugwood.org
Additional Resolutions & Image Usage

EDDMapS Distribution:
This map is incomplete and is based only on current site and county level reports made by experts and records obtained from USDA Plants Database. For more information, visit www.eddmaps.org
 


State(s) Where Reported invasive.
Based on state level agency and organization lists of invasive plants from WeedUS database.


Invasive Listing Sources:
Alabama Invasive Plant Council
Faith Campbell, 1998
Florida Exotic Pest Plant Council
John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
Mid-Atlantic Exotic Pest Plant Council, 2005