Introduced as an aquarium plant during the 1900s (and still on sale today!), Brazilian waterweed has since choked up the waterways across the United States. It forms dense mats which take over native plant habitat and degrade waterfowl and fish habitat. It reproduces only though stem fragments.
This aquatic plant is submerged but its flowers will emerge during the early summer. The flowers are small and white with only 3 petals. Its leaves are small (1" long) and serrated. They whorl around the stem in groups of 3 - 6. The leaves look similar to hydrilla (see right) but the underside of the midrib is smooth - not spiney.
Fact Sheet: Brazilian Waterweed
Photo credits (left to right): [Above]Robert Vidéki, Doronicum, Bugwood.org; Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
[Below] (left to right): Kristen Peters and USDA