Water Lettuce is a free-floating plant with many spongy, dusty green simple leaves.
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Water Lettuce (Pistia stratiotes)

Water Lettuce

Water lettuce is a free-floating plant with many spongy, dusty green simple leaves. The leaves are covered in very fine hairs and arranged in a spiral pattern from the center of the plant. This plant looks The leaves are 1 to 6 inches wide and have large veins running their length. The flowers are seldom seen. Water lettuce is a very aggressive invader and can form thick floating mats. If these mats cover the entire surface of the pond they can cause oxygen depletions and fish kills. Water lettuce should be controlled so they do not cover the entire pond.

It's easy to see where this subtropical free-floater got the name water lettuce. Shaped like romaine, the 8-inch leaves are undulating, velvety fans that stick up from the water, near white on the base and undersides. Little green flowers are negligible, but the roots, which mature from white to purple to black, hang 18" and make a great fish nursery. It is a noxious weed in southern states (it can't be shipped to California, Texas, Louisiana, or South Carolina); grow it as an annual north of Zone 8.

Water Lettuce Control Options


Water lettuce can be removed by raking or seining it from the pond's surface.


The active ingredients that have been successful in treating water hyacinth include diquat (E), glyphosate (G), imazapyr (E). E = excellent, G = good

Resources: Department of Wildlife and Fisheries Sciences, Texas A&M University

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Products to Control Water Lettuce

Gull wing

GullWing contains the active ingredient, imazapyr, which inhibits the plant enzyme AHAS (acetohydroxyaced synthase). Habitat is a systemic herbicide that is effective on post-emergent floating and emergent aquatic vegetation. Imazapyr is effective at low-volume rates and does not contain heavy metals, organochlorides or phosphates, making it safe to humans and livestock. GullWing requires the use of a spray adjuvant when applying on post-emergent vegetation.


Redwing is a liquid diquat formulation that has been effective on coontail. It is a contact algaecide and herbicide. Contact herbicides act quickly and kill all plants cells that they contact.


Avocet is a glyphosate formulation that has been effective on water hyacinth. These are broad spectrum, systemic herbicides. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides. An aquatically registered surfactant (see the label) will have to be added to the glyphosate solution for good results.

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