Wolffia spp.
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.