Medicago polymorpha
bur medic, bur-clover, bur-clover or medic, burr medic, California burclover, smooth medic, tooth bur clover, tooth medic, tooth medick
procumbent, decumbent, or ascending.
blades obovate, obcordate, or cuneate, 8–20 × 7–18(–20) mm, margins usually serrate, rarely laciniate, on distal 1/3–1/2.
(1 or)2–6(–10)-flowered, racemes.
3.5–6 mm;
calyx sparsely pubescent, hairs eglandular, lobes equal to tube;
corolla yellow, usually less than 2 times length of calyx.
with 1.5–7 coils, discoid, short to long cylindrical, or conical-truncate, 2–12 × 4–10 mm, usually glabrous, margin usually prickly, sometimes tuberculate or prickleless, prickles, when present, often relatively thin and flexible, base 2-rooted, 1 root arising in dorsal suture, other in submarginal vein;
faces moderately soft, sometimes very hard at maturity, coil face with transverse veins anastomosing in outer part of coil before entering lateral vein near coil edge.
2–12, light yellow to brownish, reniform, 2–4 × 1.5–2.2 mm;
radicle 1/2 seed length.
margins laciniate.
= 14, 16.
Medicago polymorpha
Medicago polymorpha is one of the more important annual medics that have been developed for use as pasture forage for dry, hot environments. About a dozen cultivars have been bred.
Medicago polymorpha is the most likely species of the genus to be confused with other species. The fruits are easily misidentified as one of the hard-fruited Medicago (M. rigidula, M. truncatula, M. turbinata), but are fairly similar to those of certain of the soft-fruited taxa, particularly M. laciniata and M. minima, two species that are also quite common as weeds. The fruit coil faces of both of the latter species have distal veinless areas. The coil face of M. polymorpha has quite reticulate venation, whereas that of M. laciniata has notably S-shaped radial veins that anastomose little. Medicago minima is a quite hairy plant, whereas M. polymorpha is almost always glabrous.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
Go Botany, 
LA Plants, 
MI Flora, 
MO Plants, 
PNW Herbaria 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
