Forest and Kim Starr, Starr Environmental, Bugwood.org
This summer annual weed is very similar and often confused with large hop clover because of its three-leaf arrangement and yellow flowers. However, the center leaflet is on an entirely separate petiole, making it easy to tell it apart from clover. The stems grow about 1 to 2 inches in length, and this weed is highly resistant to foot traffic, drought and other harsh conditions.
Postemergent herbicides with clopyralid, triclopyr and other similar ingredients will provide effective weed control. They should be applied to actively growing weeds before seed germination, which occurs when soil temperatures reach between 50 and 75 degrees F. Regular lawn maintenance is also recommended to keep black medic from reoccurring in the turf.