Medicago lupulina is an annual or short-lived herbaceous perennial belonging to the legume family. It reproduces by seeds and is an aggressive weed of lawns, pastures, and other disturbed sites.
It is easily identified by its green to dark-green trifoliate leaves with three oval leaflets and dome-shaped clusters of bright-yellow flowers.
Black Medic Classification
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Tracheophyta
- Subphylum: Angiospermae
- Class: Dicotyledonae
- Order: Fabales
- Family: Fabaceae
- Genus: Medicago
- Species: Medicago lupulina
- Common Names: Black Medic, Black Nonesuch, Black Clover, Yellow Trefoil, Hop Medic, Black Hay, and English Trefoil
Nativity and Distribution
Black Medic is native to Europe, Asia, and North and East Africa. Today, it has been naturalized in other regions, including North America, most of South America, South Africa, New Zealand, India, China, and Australia.
Physical Characteristics
- Leaves: Green to dark-green leaves with 3 oval leaflets
- Fruits: Kidney-shaped, 1.5-3mm wide, single-seeded pods
- Stems: Slender, slightly hairy stems, about 10-45 cm long
- Flowers: Rounded clusters of tiny, bright-yellow flowers
- Roots: Taproot system
Hop Clover is a shallow-rooted, annual or short-lived perennial, herbaceous broadleaf that grows 15-80 cm long. It belongs to the legume family and is closely related to true clovers.
You can easily identify M. lupulina by its green to dark-green trifoliate leaves with three oval leaflets and dome-shaped clusters of bright-yellow flowers.
Leaves are alternate, trifoliate, green to dark green, with each leaf dividing into three ovate leaflets. The leaflets are compound, 5-15 mm long, prominently veined, and have somewhat toothed margins.
The outer leaflets are attached to the stem, while the middle leaflet slightly protrudes on an extended stalk. There are a pair of stipules that are lanceolate to ovate, at the base where the petiole meets the stem.
Stems are slender, prostrate or ascending, light green to reddish-green, 10-45 cm long. They may have white hairs, which decrease as the plant reaches maturity.
Nonesuch produces dome-shaped, compact clusters, about 6mm wide, each of 10-50 tiny, peal-like, bright-yellow flowers, each 3mm wide. Flowering occurs from April to September, depending on the prevailing conditions.
The seed is oval, smooth, olive green to brown, about 2mm long, with a small point on the concave side.
Reproduction, Dispersal, and Life Cycle
- Life Cycle: Annual or Perennial
- Seeds: A prolific seed producer
- Climate: Temperate and subtropical climates
- Dispersal: Wind, water, animals, and human activity
Medicago lupulina behaves as a summer or winter annual and sometimes as a short-lived perennial. It thrives in temperate and subtropical climates and reproduces by seed.
A single plant is reported to produce over 6000 seeds. The seeds first fall from the mature pods before being dispersed by other agents like animals, wind, water, and human activities like tillage and mowing.
The seeds are generally viable and germinate quickly where ideal conditions occur. Seeds that germinate in mid-summer remain vegetative, and those that survive winter emerge the following spring.
Immature plants can flower within six weeks after emergence, while a mature plant continues to produce inflorescences throughout the growing season. The seeds buried underground can remain viable for many years.
Hop Clover thrives in dry or moist, nutrient-deficient, neutral, and slightly acidic soils and prefers sunny areas. However, it can adapt to a variety of environmental conditions.
Where it occurs in lawns, it can be an indicator of low nitrogen levels. Black Medic can also be found in pastures, fields, agronomic crop fields, gardens, vineyards, riverbanks, roadsides, and other disturbed sites.
Similar Plants
- Medicago polymorpha
- Trifolium campestre
- Trifolium aureum
- Trifolium dubium
- Oxalis stricta
Uses
- It is grown as a fodder plant in sheep pastures and is also used for forage and hay.
- It is a common plant in cover cropping rotations meant to improve nitrogen levels and overall soil fertility.
- Hop Clover is grown on dry land to create artificial meadows.
- It is used in orchards and vineyards for moisture and organic matter preservation and weed growth prevention.
- It is used for soil remediation where high levels of heavy metals like lead (Pb) are observed.
- Black Medic is used to stabilize soil in areas like roadside borders.
Impact on Farms and Environment
Black medic is an aggressive weed in cropping systems. It can be found in crop fields, vineyards, and orchards, where it competes for important nutrients and light.
What makes it a persistent weed that requires repeated control is that it can thrive in poor conditions, and its long seed viability continuously keeps sprouting up in the growing seasons.
Hop clover is also a common weed of lawns, especially in poorly maintained turf. It may also be an indicator of low nitrogen levels.
The weed further weakens the turf by competing for important resources while fixing its own nitrogen levels to thrive. It also causes even and unsightly patches on manicured lawns.
Additionally, its long taproot makes big infestations difficult to control and may require more expensive strategies to limit the spread.
Overall, where a Nonesuch invasion occurs, including riverbanks, fields, pastures, and other disturbed sites, it can potentially outcompete and displace native vegetation. Its long seed viability and adaptability to different conditions will require consistent efforts to prevent germination and establishment.
Control
- Cultural control: Improved turf management and core aeration
- Mechanical control: Hand pulling and mowing
- Chemical control: Herbicides like fluroxypyr, MCPP, and dicamba
In lawns, you can prevent Black Medic growth by improving practices that encourage dense growth, such as proper fertilization, irrigation, and mowing at a 3-inch range.
Eliminating soil compaction through core aeration in areas such as sidewalks,curbs, and roadsides can also help discourage weed growth.
Hand-pulling is a viable option for small infestations of even mature plants, especially when the ground is moist, while mowing at a 3-inch range can help remove larger infestations on lawns. Hoeing and cultivation are recommended for small areas like gardens.
Ensure that you remove the weeds before they flower and set seed.
For larger areas, applications of postemergence herbicides from late spring to early summer, such as dicamba, fluroxypyr, 2,4-D, triclopyr, and MCPP, can effectively control Black Medic.
Lead Editor for Insight Weeds.