Herbs: shoots ± pubescent, hairs eglandular, sometimes also glandular. Stems procumbent to ascending. Stipules: margins dentate to laciniate. Leaflets: blades cuneate to obovate, (4–)6–12 × (3–)4–8 mm, margins serrate on distal 1/2. Inflo­rescences 1–3(–6)-flowered, racemes. Flowers (3–)4–6(–8) mm; calyx pubescent, hairs eglandular and/or glandular, lobes shorter to longer than calyx length; corolla yellow, less than 2 times length of calyx. Legumes with (4–)5–6.5(–7.5) coils, coils weakly to strongly adpressed, usually ovoid, sometimes cylindri­cal, discoid, or spherical, 5–10(–12) × 5–10(–15) mm, usually pubescent with eglandular and gland-tipped hairs, evident only when young, when glandular, often producing velvety appearance, rarely glabrous, margin prickly, tuberculate, or prickleless, prickles, when present, at different angles to plane of coil, very stocky and difficult to bend, base often round, 2 roots often apparent at maturity; faces very hard at maturity, coil face with strongly curved radial veins anastomosing somewhat towards coil periphery, veins obscure at maturity from developing spongy tissue. Seeds yellow to yellow-brown, reniform, (2.5–)3–4(–4.5) × (1.3–)1.5–2(–2.5) mm; radicle 1/2, or slightly less, seed length. 2n = 14, 16.

Phenology: Flowering spring–summer.
Habitat: Roadsides, fallow ground, open woodlands, shrublands.
Elevation: 0–400 m.

Distribution

• Generated Map
• Legacy Map

Loading map...

Introduced; Calif., Mass., w Asia, introduced also in Australia.

Discussion

Medicago rigidula has been sown for forage only to a limited extent. There are a few forage cultivars, including ‘Laramie’, a self-regenerating pasture species for the Central High Plains of the United States.

The European and African populations of this species complex have been segregated as Medicago rigiduloides E. Small, based particularly on pollen morphology and fruit characters (E. Small et al. 1990). Additional studies confirming separation of these taxa are needed (D. C. Heft and R. W. Groose, http://www.naaic.org/Publications/ 1996Proc/poster_session.htm), before deter­mining their applicability to the plants in the flora area.

Selected References

None.

Lower Taxa

None.