Waterlettuce Pistia stratiotes

A field of free-floating weeds resembling the open heads of lettuce or immature cabbage plants on still or slow moving water.

  • English Name: Waterlettuce
  • Latin Name: Pistia stratiotes
  • Propogate: Mostly offshoots of new plants, also by seeds
  • Symptoms: A field of free-floating weeds resembling the open heads of lettuce on still or slow moving water
  • Dangers: Blocks sunlight from reaching submerged plants, affects boating and recreation

The complex design of the simple looking Water Lettuce

The Water Lettuce - scientific name, Pistia Stratiotes - is a complex weed despite its simple cabbage look. In the right season, the nicely arranged leaves hide a flower that is hard to spot at first glance. The flower matures into a seed that forms one reproductive system for the plant. At the same time, the each plant forms offshoots of new plants from the side, which quickly grow into new plants while remaining connected to the mother plant until their weight, wind or water currents eventually break them apart. The effect is that while each plant appears to grow singly, many of the plants are linked together by a network of shoots to form a tight mass of weeds. They are, in other words, communal weeds. That linkage is important because the Water Lettuce is a free floater with no anchorage to the water bed. Holding together allows the whole body of weeds to resists wind and water currents that would otherwise restrict their spread. The roots hang in the water and are as feathery as the leaves. Each plant has lots of roots, in keeping with the communal spirit.

Water lettuce weed control

Water Lettuce weeds are surprisingly aggressive colonizers of their environment. Using the vegetative offshoots, they grow rapidly, taking over just about every available space in the water. In high nutrient water such as water contaminated sewage or fertilizers the weed has been known to have up to 1,000 of those offshoots in a meter square of water. The Water Lettuce weed is a popular aquarium plant and looks good in ornamental ponds. But in the wild, it is a problem. It does clean water of waste such as sewage, and prevents algae blooms but water birds or animals rarely eat it. The result is that wherever it gets a footing, it grows into a hindrance to fishing, transportation and recreational use of the water. In places where it becomes necessary to control Water Lettuce, two methods are normally used. In very large water bodies, two insects a weevil from South America and a moth from Thailand have shown great promise in eating their way through the weed. In smaller water bodies, such as ponds, dams and small lakes, the typical control method is physical removal. The Deskuzzer, one of our weed control products, is a particularly effective tool for the job because it has a long reach that allows one person to cover a wide area of the water from one position. The Deskuzzer is a 5 foot wide floating seine with sturdy abrasion, ultra tough screen, and a 24 foot pull line.