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Watermeal

Wolffia spp.

Watermeal Locations in North America
Watermeal Locations in Southeast US

watermeal drawing
watermeal on a finger
watermeal on two fingers


USDA, NRCS. 2018. The PLANTS Database (http://plants.usda.gov, 28 March 2018). National Plant Data Team, Greensboro, NC 27401-4901 USA.
Illustration courtesy of University of Florida/IFAS Center for Aquatic and Invasive Plants. Used with permission.

What is Watermeal?

Overview

Physical Characteristics

Body:

  • Rootless
  • Floating plant
  • Barely visible to the naked eye
  • Form large, green masses on the surface of water (thin green scum)
  • Spherical or oval shape, sometimes flattened
  • About the size of a pinhead

Where Does it Grow?

Often watermeal will be associated with colonies of duckweeds. They grow on the surface of lakes, ponds and marshes.

Is it Invasive?

Although watermeal is native, it can be a nuisance in ponds and are often found mixed in with duckweed or mosquito fern. If colonies cover the surface of the water, then oxygen depletion and fish kills can occur. These plants should be controlled before they cover the entire surface of the pond.

Pros and Cons of Watermeal

Watermeal is not known as an important food but many ducks may consume it and often transport it to other bodies of water. Dense colonies of watermeal often can completely cover the surface of a pond and will cause dissolved oxygen depletion and fish kills. These colonies will also eliminate submerged plants by blocking sunlight penetration.

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Photo Credits: The majority of the aquatic plant line drawings are the copyright of the University of Florida Center for Aquatic Plants (Gainsville). They are used with permission.

Aquatic plant photographs were provided by David Bayne, Jim Davis, Kelly Duffie, Billy Higginbotham, Michael Masser, John Clayton, Chetta Owens, Diane Smith, Joe Snow, Don Steinbach, Bridget Robinson Lassiter and Peter Woods.

You may use these photos, so long as you give credit to AquaPlant.

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