Dollarweed, also known as marsh/water pennywort, is a perennial aquatic weed native to North and South America. It can be found in southeastern US where it grows on beach dunes, and in moist open sandy areas, marshes, ponds, water filled ditches and well-watered lawns and flower beds. An edible weed, it can be used in salads and as a pot herb.
Dollarweed has creeping, prostrate or floating stems two the three inches long that carry bright green glossy leaves that are round with slightly scalloped edges. The cup shaped leaves are one to four inches across and are attached to the stem on their underside (a characteristic called peltate). In late summer, star-shaped flowers with five white to yellow petals are produced in umbels one to four inches wide. Plants reproduced by rhizomes and seeds.
Plants are difficult to control by either pulling or spraying. Begin with digging up the plants before they flower being especially careful to get the rhizomes to prevent resprouting. When the plant is in a lawn, reduce irrigation water to weaken the plant so that grass can crowd dollarweed out. In especially difficult situations, an herbicide such as imazaquin can be applied in late spring when the foliage is tender and more susceptible to spraying but us herbicides away from water sources to prevent contamination.