mild waterpepper, swamp smartweed
Polygonum hydropiperoides is found in marshes, swamps, cypress domes, lake shores, and pond margins. It is common nearly throughout the state of Florida and blooms from spring to fall (Wunderlin, 2003).
Swamp smartweed is located in almost all fifty states, and in parts of Canada (Kartesz, 1999).
For brief control information, see Efficacy of Herbicide Active Ingredients Against Aquatic Weeds (EDIS Pub #SS-AGR-44)