Water Lettuce
Pistia stratiotes
Center for Aquatic Plants
|
Water LettucePistia stratiotes |
| University of Florida, IFAS, Center for Aquatic Plants |
Invasive Nonindigenous Plants in Florida |
Water lettuce (Pistia stratiotes) is a
floating plant that grows in lakes, rivers and canals, occasionally forming
large dense mats of bright green plants, as in this photo of Mike Netherland standing next to
Lake Alice on the University of Florida campus.
Experts disagree as to whether water lettuce is a native plant or has been introduced. If water
lettuce was introduced, it was quite a while ago: the plant is featured in a drawing by the explorer, William Bartram, in 1765. Bartram wrote that
he saw,
Today, this plant is generally under maintenance control in Florida. Maintenance control means
that
plant managers have the plants at a low level, and keep them at a low level
using herbicides, machines and biocontrol insects.
If only a year passed without constant vigilance by the couple of hundred aquatics management
agencies in the state, water lettuce likely would return to the high
infestation levels experienced in the past.
Water lettuce is a free-floating plant. As its name
implies, water lettuce resembles a floating open head of lettuce. Water lettuce has very thick
leaves. The leaves are light dull green to blue-green, are hairy, and are ridged. There are no leaf stalks. Water lettuce
roots are light-colored and feathery. Its flowers are inconspicuous.
Water lettuce reproduces vegetatively by short runner
stems (stolons) that radiate from the base of the plant to form daughter plants, and
also reproduces by seed.
