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Ecological Importance

Watermeal is common in stagnant and slow moving waters. From time to time waterfowl may consume watermeal. Watermeal is often used as camouflage cover for fish, amphibians, reptiles, etc.


Watermeal is often misidentified as algae or "green pond scum." Watermeal can easily cover the entire pond, especially when little or no wind is present. Wolffia continues to germinate all season adding to its persistent nature.

Plant Description:

Watermeal is a very tiny (less than 1 millimeter) light green free-floating, rootless plant. In fact, watermeal is the smallest seed-bearing plant in the world. Watermeal tend to grow in dense colonies in quiet water, undisturbed by wave action. Watermeal is often found growing with duckweeds or mosquito fern.

Hints to Identify

  • Resemble specks of cornmeal floating on the water.
  • Color is shiny deep or lime green
  • Size is about half the size of a grain of rice, sometimes no larger than poppy seed.
  • Shape is slightly elliptical or round.
  • Wolffia has no root structure. Place a finger or two into the water and withdraw it, your fingers will be coated with these small distinct green bb's. Rub your thumb and forefinger together, they will feel like miniature ball bearings.
Homeowner Treatment Options
Sonar AS
Sonar RTU
*Aquatic Biologists recommends implementing preventative management techniques and physical removal prior to, or in conjunction with treatment.

Common Application Questions

Q. How much should I treat?

A. You should treat the entire pond.

Q. When is the best time to treat?

A. Once water temperatures are around sixty degrees or warmer.

Q. How often do I need to treat Watermeal?

A. One- three treatments may be needed throughout the growing season depending on which product you use.