Medicago lupulina L.
CC = *
CW = 3
MOC = 66
Family - Fabaceae/Faboideae
Stems - To 45cm tall but typically less, erect to ascending, multiple from base, branching, from a taproot, typically purple at the base and on stems that face the sun, pilose, herbaceous, 4-angled.
Leaves - Alternate, petiolate, stipulate, trifoliolate. Stipules large, foliaceous, generally ovate, acuminate, to 1.5cm long, 5mm broad, glabrous adaxially, pilose abaxially, with 1-2 pointed lobes at the base or not. Petioles to +3cm long, sparse pilose. Lateral leaflets with petiolules to 1mm long and pilose. Petiolule of terminal leaflet to 4mm long. Leaflets elliptic to obovate or rhombic, entire or shallow serrate or sinuate in the apical 1/2, emarginate at the apex and with a short mucro. Lateral veins parallel. Blades sparse pilose adaxially, pilose abaxially.
Inflorescence - Axillary pedunculate racemes. Peduncle longer then the subtending leaf and pubescent as the stem, some hairs glandular. Raceme to 1cm long, dense in flower. Each flower subtended by a single minute bract. Bract linear, -1mm long. Pedicels to -1mm long in fruit, pilose.
Flowers - Corolla yellow, papilionaceous, to 5mm long. Standard to 3mm broad, mostly glabrous, typically with apical margins revolute. Keels apically fused. Wings connate basally to keels. Stamens diadelphous. Anthers pale yellow, to .1mm broad. Ovary green, glabrous, +1mm long, compressed. Style short, green. Calyx 5-lobed. Lobes attenuate, the longest to 1mm long, pilose externally, glabrous internally. Fruits dark brown to black when mature, reniform or cochleate, 3-4mm long, 2mm broad, compressed, sparse pilose, reticulate.
Flowering - February - December.
Habitat - Lawns, fields, waste ground, roadsides, railroads.
Origin - Native to Eurasia and Africa.
Other info. - This little species is a big time weed found throughout Missouri. The plant spreads easily and can form large colonies when left untouched. The small fruits of this plant turn black when ripened and look like small kidneys.
Photographs taken in Ellington, MO., 6-3-01, and in Gainesville, FL., 2-11-03.