Watermeals are the smallest flowering plants in the world. They are a very tiny (less than 1 millimeter) light green free-floating, rootless plant. Watermeal tends to grow in dense colonies in quiet water, undisturbed by wave action. Watermeal can be an aggressive invader of ponds and are often found mixed in with duckweeds.
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.
Control can be expensive as normally the entire volume of water needs to be treated. Control attempts often fail due to the resistant nature of the plant.