Other common names
Black medick, yellow trefoil, black clover, hop clover, black hay, etc.
A low-growing spreading weed commonly found in lawns or pastures, black medic can be differentiated from other common lawn clovers by its yellow flowers. It grows well in dry soil low in nitrogen or compacted soil.
Typical plant growing in disturbed site. Photo by S. Donaldson.
Compound, with three oval leaflets with visible teeth at the tips. The central tooth on each leaflet is a bit longer than the others. The center leaflet has a longer stalk. Leaves have soft hairs.
This photo shows two compound leaves, each made of three leaflets. Note the tooth at the tip of each leaflet. Photo by W. Hanson Mazet.
Grow flat to the ground, branch, and may be more than a foot long. Stems are softly hairy.
Yellow flowers are tiny and group together in clusters of as many as 50 individual flowers. Blooms from spring to mid-summer. Seedpods turn black at maturity.
The tiny individual yellow flowers are arranged in clusters to form the flower heads. Photo by S. Donaldson.
Grows a thin taproot with many fine, spreading roots.
Eastern Europe and Asia
Where it grows
Lawns, pastures, gardens, roadsides, crops and forests
Annual (sprouts, flowers and dies in a single year); sometimes lives longer
Reproduces by seed
Seedlings leaves are pale on the underside. Photo courtesy of J. DiTomaso, UCCE.
Control relies on preventing production of seed. Each plant can produce thousands of seeds, which live for several years.
Dig, hoe or pull small patches. It’s easiest to pull them when the soil is moist. Mowing alone does not provide control.
Encourage thick, competitive vegetation. In turf, mow high (to 3½ inches) so the grass will shade the black medic, and aerate to relieve compaction. Use thick mulches in garden settings.
Can be grazed when young, but contains substances toxic to livestock, so grazing must be carefully managed.
Apply broadleaf-selective herbicides such as 2,4-D+dicamba on young plants. Glyphosate may also be effective but is nonselective and can kill or damage other plants, including lawn grasses. Preemergence herbicides are available.
DiTomaso, J.M. and E.A. Healy. 2007. Weeds of California and Other Western States. University of California Publication 3488.
UC IPM. No date. Black medic, IPM.
UC Berkeley Jepson Manual. 2012. Medicago lupulina L., UC/JEPS.
Whitson, Tom D. (editor). 2009. Weeds of the West. University of Wyoming, Jackson, Wyoming.