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Lawn and Turfgrass Weeds: Black Medic (Medicago lupulina L.)

Black medic is a weed of home lawns, parks, low-maintenance grounds, and along roadsides.

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Updated:

October 1, 2025

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Figure 1. Black medic growing in an under-fertilized lawn in central Pennsylvania. Photo: Peter Landschoot, Penn State

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This species is often found growing in dry, marginal soils with thin turf that has not been fertilized with nitrogen. It tends to grow in a prostrate fashion, forming patches and is most noticeable when flowering during summer.

Life Cycle

Black medic is a member of the legume family (Fabaceae) and is classified as a winter or summer annual. Plants generate deep taproots and crowns produce long, spreading stems that grow prostrate along the soil surface but do not give rise to nodes and roots. This species produces flowers, fruits, and seeds from late spring to early fall. Like other legumes, black medic exists symbiotically with nitrogen-fixing Rhizobium bacteria which form nodules on roots and convert atmospheric nitrogen into a plant-available form.

Figure 2. Yellow inflorescences of black medic. A single inflorescence may contain up to 50 individual flowers. Photo: Peter Landschoot, Penn State

Identification

Black medic stems are sparsely hairy and grow close to the ground then turn slightly upright, giving rise to yellow flower clusters called inflorescences. Leaves have three oval leaflets (trifoliate arrangement) approximately 1/2 to 3/4 inch in length and arise alternately on stems. Leaf margins of individual leaflets are smooth at the base and slightly serrated towards the top, with a small spur at the tip. Black medic leaves can be distinguished from other clovers by the extended petiole on the center leaflet. A pair of leaflike stipules can be found at the junction of the main stem and each leaf.

Figure 3. Leaves of black medic showing central leaflets on extended petioles and small, leaflike stipules at the junction of stems and leaves. Photo: Peter Landschoot, Penn State

Small (1/4 to 1/2 inch), rounded yellow inflorescences develop on stalks that arise from leaf axils on stems. Each compact inflorescence is composed of multiple individual flowers which are eventually replaced by black seed pods and seeds. Seeds are viable and generate new plants. Flowering occurs throughout the summer months.

Management and Control

Infestations of black medic can be reduced by improving turf density through fertilization, regular mowing, and use of turfgrasses well-adapted to site conditions. This weed can be suppressed or controlled with various postemergence herbicides, particularly those containing dicamba, MCPP, and/or fluroxypyr.

Some postemergence herbicide products labeled for control of black medic.

Active ingredients	Product name(s)*
2,4-D and 2,4-DP	Patron 170 (ester formulation)
2,4-D, 2,4-DP, and dicamba	Super Trimec (ester formulation)
2,4-D, clopyralid, and dicamba	Millennium Ultra 2**
2,4-D, fluroxypyr, and dicamba	Escalade 2
2,4-D, fluroxypyr, triclopyr, and flumioxazin	Sure Power (ester formulation)
2,4-D, MCPP, dicamba	Trimec Classic, Threesome, Lesco Three-Way, 3-D
2,4-D, MCPP, dicamba, and carfentrazone-ethyl	Speedzone
2,4-D, MCPP, dicamba, and sulfentrazone	Surge
2,4-D, quinclorac, and dicamba	Quincept; 2DQ Herbicide; Triad QC Select, Triad SFZ Select
2,4-D, quinclorac, dicamba, and sulfentrazone	Q4 Plus
2,4-D and triclopyr	Chaser 2 Amine, Turflon II Amine
2,4-D and triclopyr	Chaser Turf Herbicide (ester formulation)
2,4-D, fluroxypyr, and triclopyr	Momentum FX2
2,4-D, fluroxypyr, triclopyr, and sulfentrazone	Momentum 4-Score
2,4-D, triclopyr, dicamba, and pyraflufen-ethyl	4-Speed XT (ester formulation)
2,4-D, triclopyr, dicamba, and sulfentrazone	Foundation
carfentrazone-ethyl and quinclorac	SquareOne
florasulam	Defendor
fluroxypyr, dicamba, and fenoxaprop-p-ethyl	Last Call Selective Herbicide
MCPA, fluroxypyr, and dicamba	Change Up
MCPA, fluroxypyr, and triclopyr	Battleship III
MCPA, MCPP, and dicamba	Trimec Encore, Tri-Power Selective Herbicide
MCPA, MCPP, dicamba, and carfentrazone-ethyl	Powerzone (ester formulation)
MCPA, triclopyr, and dicamba	Lesco Three-Way Ester II, Cool Power (ester formulation)
MCPA, triclopyr, and dicamba	Eliminate, Horsepower
MCPP	Mecomec 4 Turf Herbicide
quinclorac	Drive XLR8, Quinclorac 1.5 L, Quinclorac 75 DF
sulfentrazone	Surepyc, Dismiss
sulfentrazone and carfentrazone-ethyl	Dismiss NXT
sulfentrazone and quinclorac	Solitare, Solitare WSL
triclopyr and clopyralid	Confront**
triclopyr and fluroxypyr	Tailspin
2,4-D, triclopyr, dicamba, and sulfentrazone	Tzone SE (ester formuation)