Black Medick is an introduced sprawling to erect annual (biennial in some areas) whose stems are from less than a foot to two feet long. It has a taproot and is generally procumbent with branching from the stem base with shorter branches held erect. Stems are 4-angled and have fine whitish hair.
Leaves are tri-foliate, the terminal leaflet is stalked and the laterals are not. Leaflet shape is obovate with a rounded tip, but usually with a shallow but broad notch at the tip with an abrupt point in the notch from the termination of midrib vein. There can be fine teeth in the upper margins of the leaflets, which are seldom more than one half inch long. Both sides have hair, the underside densely. The leaf stalk is rather long for such a short plant, is hairy and ends in a pair of stipules.
The inflorescence is a dense head no more than 1/2 inch long and 1/4 inch thick on a long hairy stalk rising from the leaf axils. Large heads can contain up to 50 tiny flowers.
Flowers have bright yellow corollas composed of typical pea family structure - a banner petal, which is quite large, with two forward projecting lateral petals with the two keel petals between them. The keel petals are fused on top and contain the reproductive parts which here, are two groups of stamens with yellow anthers and a style rising from a green ovary. The large banner petal is upright, usually folding back and with a vertical fold line in the middle. The flower calyx is short-stalked, hairy with 5 long-pointed tips. Each flower is subtended by a very small bract.
Seed: Flowers mature to a kidney shaped thin-skinned pod, ridged and slightly twisted, containing one seed, black at maturity.
Habitat: Black Medick grows in disturbed places, roadsides, lawns and fields. It needs full to at least partial sun, but moisture conditions can vary from moist to dry. It spread by reseeding and can form large colonies of plants if not disturbed. Vigorous growth of larger plants will crowd them out.
Names: The genus name Medicago if from the Greek mēdike a classical name for a crop plant, in this case, Alfalfa, which has the same genus name. The species lupulina means "hop-like", probable referring to the inflorescence resembling a hop seed cluster and hence the alternate common name of Hop Clover. The author name for the plant classification 'L.' refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.
Similar plant or comparisons:: The leaf structure resembles clover plants such as the white and red clover but there the flower heads are much larger and not yellow.
Above: An erect stem section with several inflorescence. Drawing courtesy Kurt Stüber's Online Library.
Below: 1st photo - the dense heads are only up to 1/2 inch long. The upright banner petal dwarfs the other 4 petals. 2nd photo - the green calyx of each flower is densely hairy as is the flower stalk.
Below: Stems have 4-angles, fine hair. The leaf underside is densely hairy.
Below: Each leaflet has a rounded top with a broad shallow notch with a projecting point of the midrib in the center of the notch.
Below: Stems typically sprawl across the ground with the flowering portion held erect.
Below: Kidney shaped seeds of Black Medick. Photo courtesy Steve Hurst, USDA-NRCS Plants Database
Notes: It is not known when Black Medick first appeared in the Garden but being an adventitious plant it may have arrived when the Upland Garden space was added in 1944. Martha Crone listed it on her 1951 plant census. There are only five of Minnesota's 87 counties where the DNR plant survey has not found it, but it might be there also. The only other species of Medicago found in Minnesota is Alfalfa, M. sativa.
In North America it is found everywhere from the lower Canadian provinces southward and also in Alaska and Hawaii, as well as most of the temperate areas of the globe. It was imported into North America for grazing animal feed. Ada George (Ref. #6b) reported a century ago that cattle readily eat the plant and it makes good pasture as it is nitrogen fixing. She also noted that unscrupulous seed dealers would adulterate the more expensive Alfalfa seed with Black Medick seed.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"