Water Lettuce (Pistia stratiotes L.)

↑Range - Expand

Legend	Color
Introduced
Expanded
Present: Various or Uncertain Origin
Introduced or Not Present
Native or Expanded
Expanded or Not Present
Native or Expanded or Not Present

This tentative map is based on our own research. It may have limited data on Canada and/or Mexico, and there is some subjectivity in our assignment of plants as introduced vs. expanded. Read more in this blog post.

This species is agreed-upon to be native to South America through Central America into Mexico, and to have been introduced by boats to regions much farther north than its native range. Its status in the US is controversial and uncertain; POWO reports it native to FL, MS, LA, and TX, whereas FSUS reports it native only to Florida. The Texas A&M Agrilife Extension on the other hand reports it as non-native everywhere in the US. We have yet to build the portion of its map in Mexico, and for now our map for the US reflects uncertainty of not knowing which sources are correct. Because the southern portions of this species' range in the US are more-or-less contiguous with the native range, if they are non-native, we treat them as Expanded, but the more northerly ones are isolated and we treat as Introduced.