Medicago arabica
Medicago rigidula
burclover, southern bur-clover, southern burr clover, spotted burclover, spotted burrclover, spotted medic, spotted medick
rigid or Tifton bur (burr) medic, Tifton burclover, Tifton medick
procumbent to ascending.
procumbent to ascending.
blades cuneate, obovate, or obcordate, 8–25 × 7–20 mm, margins serrate on distal 1/3, often with conspicuous central, purple-red (anthocyanin) blotch adaxially.
blades cuneate to obovate, (4–)6–12 × (3–)4–8 mm, margins serrate on distal 1/2.
(1 or)2–5(–8)-flowered, racemes.
1–3(–6)-flowered, racemes.
4–5(–6) mm;
calyx pubescent, hairs eglandular, sometimes multicellular and gland-tipped, lobes equal to or longer than tube;
corolla yellow, 2 times length of calyx.
(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.
with 3–5(–7) coils, shortly ellipsoid to subglobose (ends rounded), or discoid to cylindriform (ends flattened), (4–)5–9 × (4–)5–7(–8) mm, glabrous, margin usually prickly, sometimes tuberculate, prickles, when present, often relatively thin and flexible, base 2-rooted, 1 root arising in dorsal suture, other in submarginal vein;
faces soft, coil face with venation anastomosing considerably on outer 1/3, coil edge in end view shows central groove flanked by lateral grooves to form pattern of 3 grooves separating 4 ridges, not visible in side view of coil.
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.
2+, yellow or yellow-brown, reniform, 2–3.5 × 1.2–1.5 mm;
radicle usually slightly more than 1/2 seed length.
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.
margins deeply dentate to lobed.
margins dentate to laciniate.
= 16.
= 14, 16.
Medicago arabica
Medicago rigidula
Medicago arabica is sown for forage only to a small extent.
Although the majority of Medicago plants cannot be identified to species with much certainty without fruits, in most cases vegetative plants with purplish blotches on the centers of the leaflets will be this species. However, these markings occur occasionally on other annual species of Medicago and are absent from some plants of M. arabica.
Medicago maculata Sibthorp and M. maculata Willdenow are illegitimate names that pertain here.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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