Weed with black seed head

Weed with black seed head

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.

Habitat

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.

Propagation/Phenology

Reproduces by seed; one well-developed, vigorous, plant may produce more than 1,000 seeds.

Comments

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.

Blackseed and broadleaf plantain

Family: Plantaginaceae (Plantain family)
Life cycle: Perennial, reproducing by seed
Native status: Broadleaf plantain is introduced to N. America, whereas blackseed plantain is native
Habitat: Turf, landscapes, waste areas

General description: Basal rosette of smooth, elliptic to oval leaves, up to 7 in long and 4 in wide. Leaves have prominent veins and usually inconspicuous hairs. As leaves mature the margins tend to get wavy. Flowers are inconspicuous, produced on a leafless stalk up to 10 in long. Flowers arranged in a spike that covers at least ¾ of the stalk. Has a fibrous root system.

Key ID traits: Rosette of oval leaves with prominent veins.

Similar species: Blackseed plantain can be difficult to differentiate from broadleaf plantain. Blackseed plantain usually has a red tinge at the base of leaf petioles and lacks hairs on leaf blades. Blackseed plantain has dull, black seeds whereas those of broadleaf are shiny and light to dark brown.

Miscellaneous: The plantains once were much more problematic as lawn weeds. They are much more susceptible to the growth regulator herbicides that are commonly used on lawns than many other perennial weeds. One reason for their greater sensitivity to herbicides than dandelion is the plantains have a fibrous root system rather than a taproot found on dandelions. The taproot stores more energy reserves than a fibrous root system, increasing the ability to come back from herbicide treatments.

Oval leaves with long, flat petioles characteristic of plantain. The red base of petiole suggests this is blackseed plantain.

Seedheads of broadleaf (left) and buckhorn (right) plantain

Successful weeds adapt to stresses in the environment. This plantain is able to survive a mowing height of 0.5″ or less in a creeping bentgrass golf fairway.