Vascular Plants of Williamson County

Medicago minima [Fabaceae]
small medic, small burclover

Medicago minima (L.) L., small medic, small burclover. Perennial herb, taprooted, not rosetted, several–stemmed at base, with principal branches radiating from rootstock, often with unexpanded axillary shoots, procumbent to decumbent, to 10 cm tall; shoots with only cauline leaves widely spaced along stems, soft–hairy.

Stems

Stems cylindric, to 1.5 mm diameter, internodes to 50 mm long and > subtending leaf, short–villous.

Leaves

Leaves helically alternate, pinnately–3–foliolate, petiolate with pulvinus, with stipules; stipules 2, attached to petiole to 2.5 mm and stem at node, asymmetrically triangular, 3—5.5 × 1—1.8 mm, with free basal lobe at base, entire to subentire and wavy or with short tooth on free margin below midpoint, acute to acuminate at tip (short–notched), not veiny, short–villous; petiole to 25 mm long, pulvinus above winglike stipule, < 1 mm long, whitish, with soft hairs, above pulvinus channeled, soft–hairy; rachis channeled, to 2.5 mm long, soft–hairy; petiolule = pulvinus, 0.7—0.8 mm long, white, soft–hairy; blades of leaflets ± obovate, to 13 × 4 mm, central leaflet > lateral leaflets, tapered at base, entire to above midpoint and low–serrate at and above where the widest, often somewhat notched at tip with a single tooth in notch, conspicuously pinnately veined having evenly spaced lateral veins, with midrib slightly sunken on upper surface and principal veins somewhat raised on lower surface, short–villous and with stalked glandular hairs.

Inflorescence

Inflorescence raceme, 2–flowered, axillary, bracteate, short–villous; peduncle cylindric, ± 1.5 mm long, short–villous; bractlet subtending pedicel wide at base and acuminate above, to 0.5 mm long, colorless, abscised after flowering; pedicel 0.4 mm long, short–villous.

Flower

Flower bisexual, bilateral, pealike (papilionaceous), 2 mm across, ca. 4 mm long; calyx 5–lobed, ± 3 mm long, short–villous; tube bell–shaped, 1.5 × 1.8—1.9 mm, greenish; lobes subequal, acuminate, 1.3—1.5 mm long, green with narrowly membranous margins, 1–veined, with nonglandular hairs having also stalked glandular hairs with tiny heads; petals 5; banner not clawed, obovate, ca. 3.6 × 2 mm, white to midpoint and light yellow above midpoint often with several faint nectar lines radiating on yellow and sometimes narrowly purple–red on outer margin; wings 2, oriented edge–on parallel with keel, clawed, claws linear, 1.5 mm long, white, limbs oblong–obovate, ca. 1.5 × 0.6—0.7 mm, light yellow, with 2 white, backward–pointing lobes, the upper lobe deltate and the lower lobe triangular; keel of 2 petals fused nearly base to tip on lower edge, fused limbs with wings, clawed, 2.3 mm long, > wings and < banner, claws separate only about 1/3 length, colorless with the 2 yellowish veins, limbs semicircular in outline straight along free top margins, 1.2 × 0.6 mm, light yellow; stamens 10, diadelphous (9 fused and 1 free), included in keel; filament sheet tapered, ± 1.2 mm long, white, free portion strongly curved upward, 0.5—0.9 mm long with the center filament the longest; anthers dorsifixed, dithecal, 0.2 mm long, yellowish, longitudinally dehiscent; pollen yellowish; pistil 1, 2.5—2.6 mm long, short–stalked (stipe), stalk ca. 0.2 mm long; ovary superior, lanceoloid, 1.5 × 0.45 mm, green, short–hairy on lower side, 1–chambered with several ovules on upper side; style 1 mm long but curved, white, with minute terminal stigma.

Fruit

Fruit pod (legume), spinescent and strongly 2—4–coiled, mostly 3—4–seeded, with prickles 6—8 mm across, brown, the prickles radiating from edges of pod and forward–hooked at tips (uncinate), 1—2 mm long.

Seed

Seed oblong or somewhat curved, 2.3—2.8 × 0.9—1.3 mm, dull brown, seed coat thin and papery; hilum at midpoint.

A. C. Gibson