Medicago polymorpha L.

Code

AMASP

Growth form

broadleaf

Biological cycle

annual

Habitat

terrestrial

Global description

Medicago polymorpha is a small annual lucerne, reaching up to 40 cm tall, glabrous. The stems are spread out. The leaves are alternate, compound trifoliolate, petiolate. The stipules are laciniated. The three leaflets are largely obovate, serrated in the top half and mucronate at the apex. The papillionaceous flowers are yellow in color. The fruit is a spiral pod with 2 to 4 turns, with hooked spiny hairs along the margin.
 
Cotyledons

Cotyledons are fleshy, elliptical-oblong, 18-25 x 5-6 mm, tapering to a short petiole, glabrous.

First leaves

The first leaf is unifoliolate, broadly diamond-shaped, with an truncate base and truncate apex, emarginate and with a long, thin, furrowed petiole with 2 narrow stipules at the base. The following leaves are trifoliolate: each leaflet is obovate with a truncated, emarginate, mucronate and toothed apex, the stipules are narrow and toothed. The hypocotyled axis is rather short of 10-15 mm, slightly purplish. The plantlet is glabrous.

General habit

Medicago polymorpha is a small herbaceous plant, rather prostrate. The stems can measure up to 40 cm in length.
 
Underground system

The plant has a taproot system.
 
Stem

The stem is cylindrical, slender, full and glabrous. It is prostrate to slightly ascending, light green in color.
 
Leaf

The leaves are alternate, compound trifoliolate. They are carried by a petiole, 5 to 40 mm long. At the base, there are 2 laciniate stipules. The leaflets are largely obovate, 6 to 25 mm long and 4 to 18 mm wide. The terminal leaflet, shortly stalked, is slightly wider than the lateral leaflets. The base is wedge-shape, the apex is rounded to slightly emarginated and mucronate. The margin is entire in the lower half and very finely denticulate in the upper half. Both faces are glabrous.
 
Inflorescence

The flowers are assembled in axillary clusters of 2 to 10 flowers, carried by a peduncle of 7 to 20 mm.
 
Flower

The calyx, in tube at the base and surmounted by 5 narrow tines, is 2.5 to 3 mm long. The corolla is yellow, formed by a bi-lobed standard at the top, two lateral wings and a keel. It is 4 to 5 mm long. The stamens are distributed in a group of 9 with fused filament and 1 free.
 
Fruit

The fruit is a spiny pod, strongly wound with 2 to 6 turns. It measures 4 to 10 mm in diameter. It narrows gradually towards the last turn. The margin is thickened and has many stiff hairs in hooks.
 
Seed

The seed is ellipsoid to kidney-shaped, 2.5 to 3 mm long and 1.5 to 1.8 mm wide. It is yellow to brown in color.

Algeria: Medicago polymorpha has an autumn-winter germination and a flowering from March to June.

Medicago polymorpha is an annual plant, which reproduces by seeds.

Medicago polymorpha is a zoochorous species (epi, dys, endo-zoochorous).

Medicago polymorpha may be confused with other species of the genus Medicago, such as M. sativa and M. lupulina. The main distinctive characteristics of these three species are:

Medicago polymorpha is a C3 species.

Medicago polymorpha is currently cosmopolitan. It is a plant of pasture or a weed of crops in the tropics in areas of altitude.

Algeria: Medicago polymorpha is a fairly common species in fallow lands, annual and perennial crops throughout the country. This species seems to be indifferent to the nature of the soil although more frequent on clayey soils.

Global harmfulness

Once established, Medicago polymorpha is difficult to control. Mechanical removal of the aerial part of the plant is not sufficient to eradicate it. In addition, uprooting the plant may leave taproots and other plant material. In some situations, if not properly managed, Medicago polymorpha can become a weed or invasive plant, competing with more desirable vegetation. It is considered a pest in many areas such as Arizona (USA) and most parts of Oceania and the Pacific Islands where it has been introduced.

Local harmfulness

Algeria: Medicago polymorpha is a minor "weed". Uncommon and not very abundant, it does not generally constitute a nuisance for the culture.

Food: Medicago polymorpha is consumed as a vegetable plant in China.

Fodder: Medicago polymorpha is an excellent fodder plant with rapid growth and intense productivity.

Herbarium pictures ReCOLNAT: https://explore.recolnat.org/search/botanique/simplequery=Medicago%2520polymorpha