Weed ID Guide, Weed Science Program Weeds With Black Seed Pods Shallow, taprooted, low, trailing winte r annual or short-lived perennial forb, with prostrate or ascending stems up to 30 inches long; where thick stands develop, Do you have prostrate weeds with small yellow, clover-like flowers in your garden beds or lawn? This leguminous plant from Europe and temperate Asia, commonly called black medic, is also called yellow trefoil, black clover and hop medic. Read more about this annual weed and how to deal with it in this article…
Perennial from a basal rosette with broad oval leaves. Often mistaken for the closely related broadleaf plantain (Plantago major). Found throughout the United States, primarily a weed of turfgrass.
Cotyledons are spatula-shaped and joined at the base. Young leaves oval to elliptic with leaves that encircle the stem.
Usually lacking hairs, oval to elliptic and tapered at the tip, with a somewhat waxy surface and veins that are parallel to the margins. Margins are usually wavy and toothed. Petiole bases are conspicuously red or purple tinged.
Flowers produced on unbranched stalks (scapes) that arise from the rosette. Flowering stems are 5-15 inches long, clustered with small flowers that have whitish petals and bracts surrounding the flowers.
A cylindrical, 4-6 mm long, 4-10 seeded capsule that splits below the middle.
Taproot with fibrous roots.
Blackseed Plantain (Plantago rugelii) has petioles with red or purple colorations at their bases, a lighter green, less waxy leaf appearance, and capsules that split below the middle. These are all characteristics that help to distinguish it from the closely-related Broadleaf Plantain (Plantago major). Additionally, the leaves of blackseed plantain are hairless, and have toothed and wavy margins, unlike the leaves of broadleaf plantain.
Weeds With Black Seed Pods
Shallow, taprooted, low, trailing winte r annual or short-lived perennial forb, with prostrate or ascending stems up to 30 inches long; where thick stands develop, stems may become erect, obtaining heights of 18 to 24 inches; 4-angled stems are typically purple at the base, hairless or more rarely with some short hairs, although older stems become less hairy; they branch occasionally.
Leaves: Alternate, compound leaves are trifoliate (cloverlike); younger leaves, toward the stems tips, have short hairy petioles; older leaves have longer petioles (up to 1-3/16 inches long); paired stipules at petiole base are lanceolate to ovate and variable in size; leaflets are up to 9/16 inch long and about half as wide; medium to dark green, wedge shaped or obovate, hairy or nearly hairless, finely toothed with prominent veins.
Flowers: Flowers February to December; 2 to 8 small, bright yellow flowers are borne in clusters about 1/2 to 3/4 inch long; each flower is about 1/8 inch long; when fully open, it has a pealike floral structure with an upper standard and lower keel.
Fruit: Fruit is a spirally twisted, thick-walled pod; each pod is black, about 1/8 inch long and contains a single dark seed that is somewhat flattened and kidney shaped, less than 1/8 inch long.
Cultivated and disturbed or degraded sites in meadows, grassland, woodland, and forest communities, and roadsides within elevations that generally range from 4,000 to 8,000 feet.
Reproduces by seed; one well-developed, vigorous, plant may produce more than 1,000 seeds.
Native to Eurasia and Africa; black medick easily spreads and can form large colonies and where it is allowed to grow undisturbed, black medick may displace native species. Prior to fruiting, black medic could be confused with burclover. This species generally occurs as a weed in wildland areas of the Southwestern Region rather than as an invasive plant.
Black Medic, Medicago lupulina
A dense infestation of black medic.
Black medic, Medicago lupulina, is a common, prostrate broadleaf weed that is found throughout the US and Southern Canada. Native to Europe and temperate Asia, this member of the legume family (Fabaceae) has a few other common names including yellow trefoil, black clover and hop medic. Its is most often found as a weed in in dry, sunny areas in turf and waste ground, such as along roadsides and railroads, but it can be a nuisance in gardens and fields as well. Black medic can be an indication of low soil nitrogen in lawns as it outcompetes weak grass. Black medic and white clover grow in similar sites and are often found growing together in turf. Although it is classified as a cool season summer annual, in mild winters some plants may survive to act as a perennial. It spreads easily by seed and will form large colonies if left undisturbed.
A young black medic plant.
Black medic produces a long taproot that grows deeply into most soils. Several trailing, slightly hairy stems grow out from the base. The plant grows close to the ground, spreading up to 2 feet, but does not root along the stems. Like other members of the legume family, black medic has a symbiotic relationship with Rhizobium bacteria that form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby.
A black medic seedling (L) and trifoliate leaf (R).
The tiny seedlings resemble other clovers, with elongate, dark green cotyledons and rounded first leaf. All other leaves are trifoliate. The plant’s dark green leaves are similar to clover leaves, with three oval leaftlets. Each ½-¾” long leaflet has a small spur or tooth at the tip, toothed margins, and prominent, parallel veins. The center leaflet protrudes slightly on an extended petiole. This characteristic, along with the small projecting tip at the leaflet apex and toothed margins, help to distinguish black medic from other trifoliate legumes. The leaves are produced alternately along the stems. There is a pair of stipules (small, leaflike appendages) where each petiole joins the main stem.
Black medic flower.
The small, bright yellow flowers are produced from the leaf axils. Each inflorescence is a compact, rounded to slightly elongated cluster of 10-50 tiny flowers. Flowers can be found throughout the growing season, although individual plants stop blooming once seeds are set. Honeybees and other bees visit the flowers. The fruits that form after pollination look like small kidneys arranged in clusters. The coiled seed pods turn black when ripe. Each seed pod contains a single gold or brown seed.
In lawns, black medic can be managed through good turf management practices that encourage a dense stand of turf (high mowing, proper fertilization and irrigation), making it difficult for black medic to persist. As black medic often grows where some soil compaction has occurred, such as along curbs and sidewalks, reducing compaction will also help.
Black medic fruits (L) and ripe seed pods (R).
Black medic produces viable seed under normal mowing conditions which can persist in the soil for years, so it is important to control this weed before flowering and seed set. Individual plants can be hand pulled. Even larger plants are easy to pull out, particularly after rain has softened the soil. However, for large areas or dense infestations, a broadleaf herbicide can be applied to actively growing plants during the seedling to flower growth stage. Chemical controls are best applied from late spring through early summer and again from early through mid-autumn. Read and follow label directions carefully.
– Susan Mahr, University of Wisconsin – Madison