Dollarweed (pennywort)

Dollarweed, also called pennywort (Hydrocotyle spp.), is a creeping perennial broadleaf with round, bright green, waxy, shiny leaves roughly an inch in diameter and scalloped along the margin, resembling a small coin. The single most diagnostic trait is that the leaf stalk (petiole) attaches at the center of the leaf blade, so the leaf is held like a tiny umbrella. This center attachment separates dollarweed from dichondra, whose smaller leaves are notched, kidney- or C-shaped, and attach the petiole at the leaf edge. Plants produce small white flowers in umbrella-like clusters and spread along the ground by rhizomes.

Dollarweed degrades the stand by forming dense mats of round, waxy leaves that shade and crowd out turfgrass, producing conspicuous bright-green patches that contrast with the lawn and signal underlying drainage or irrigation problems. As colonies thicken they outcompete desirable grass for light and space, thinning the turf, and the waxy leaf surface that helps it tolerate wet sites also makes the patches stand out and persist if the moisture problem is not corrected.

Dollarweed is a warm-season perennial that spreads aggressively by rhizomes (and, in some species, tubers and seed), allowing it to form expanding colonies and to regenerate from underground parts even after top growth is removed. It is favored by warm, moist conditions and grows actively through the warm season, with the interconnected rhizome system making isolated hand-removal difficult because fragments left behind resprout.

Dollarweed is strongly associated with moist to wet, nutrient-rich sites and is one of the clearest indicators of overwatering or poor drainage in turf. It thrives where irrigation is excessive or not adjusted to need, in low spots, near downspouts, and along chronically damp areas, and can quickly invade even healthy warm-season lawns such as St. Augustinegrass, particularly during cooler, wetter periods. Reducing the moisture that favors it is central to limiting its spread.