James H. Miller, USDA Forest Service, Bugwood.org
This perennial broadleaf weed prefers moist soil but also adapts well to dry conditions. It withstands low mowing heights and can thrive in most any soil. It develops smooth leaves that cluster at the base and produces flower heads in stalks that stretch up from the center of the weed. Overwatered lawns are very susceptible to this particular weed species.
Reduce irrigation to keep this weed from establishing in the grass. Using an herbicide with 2,4-D or triclopyr or a combination of both can help to bring this weed under control. Regular lawn maintenance techniques such as soil aeration and reduced watering can help to keep it from returning.