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Black Medic
Medicago lupulina

Photo: Black Medic, Medicago lupulina

General description

Black Medic is usually first noticed when it produces numerous round yellow flowers in clover like clusters. Flowers eventually form black seedpods that persist on dark brown to black prostrate stems. A legume that is a summer annual with alternate compound leaves with 3 leaflets that closely resembles clover. Toothed stipules are present at the petiole bases. Forms a shallow taproot with small nodules. Often mistaken for wood sorrel (Oxalis).

Closeup of black medic

Management

Cultural control: Maintain healthy, dense turf that can compete and prevent weed establishment.
Mechanical control: Hand pulling or using an appropriate weeding tool are the primary means of mechanical weed control in lawns. This is a viable option at the beginning of an infestation and on young weeds. Hand pulling when the soil is moist makes the task easier. Weeds with tap roots like dandelions or have a basal rosette (leaves clustered close to the ground) like plantain are easier to pull than weeds such as Bermudagrass (wiregrass) or creeping Charlie (ground ivy) that spread with stolons or creeping stems that root along the ground.
General chemical control: Spot treat weeds with a liquid, selective, postemergent, broadleaf weed killer applied when weeds are actively growing. Look for a combination product the following active ingredients:
2, 4-D, MCPP (mecoprop),  Dicamba* or Triclopyr. 

*Do not spray herbicides containing dicamba over the root zone of trees and shrubs. Roots can absorb the product possibly causing plant damage. Read the product label for precautions. 

Organic control

For a glossary of herbicide terms and additional information see: control options