Black medic (Medicago lupulina) is a low-growing plant that grows in the summer although it can also be spotted in winter sometimes. This is the reason it is also referred to as an annual or short-lived perennial plant. Black medic can be a nuisance in your garden, but the good news is that getting rid of it is pretty straightforward.
The plant sprouts from adventitious buds on roots or seeds and can grow to heights of about 32 inches. Even though they have tiny fibrous roots, those that have survived for more than a year develop a deep taproot. This weed has teardrop-shaped leaves similar to those found on clovers. The leaves are generally in groups of three with the center one spotting a longer petiole. The leaflets are hairy with a toothed shape towards the tip. Black medic blooms from April through July. Typically, you would see ten to twenty yellow flowers in dense clusters that form a rounded flower head. The fruit is a small kidney-like ovoid that can be as long as two millimeters. It is also strongly veined and usually turns black when ripe. It contains one amber colored seed.
History and Distribution
Black medic is a native of the old world and thrives in dry to moist well-drained soils. This explains its distribution all over the world and throughout the United States. It is a common plant in grasslands, pastures, gardens, lawns, roadsides and crop fields. Its global distribution is facilitated by the fact that this weed grows at altitudes as high as 1,800 meters, and it is also resistant to cold. Despite its ability to grow and thrive in varying climatic conditions, it does not do well in shady areas. Many broadleaf weed killers will kill this weed, and several commercial grade pre-emergent weed control products can prevent it from germinating and taking root in the first place.