Common Australian Garden Weeds

Medicago polymorpha

Scientific name: Medicago polymorpha L.


Burr medic (Medicago polymorpha) with small yellow flowers, trifoliate leaves and immature coiled fruit with spines.


Trifoliate leaves and flowers of burr medic.


Close-up of the pea-shaped flowers and dentate leaflet margins.


Close-up of immature coiled and spiny fruit.


Seedling of burr medic.

Synonyms: Medicago lappacea Desr.; Medicago hispida Gaertn. var. lappacea (Desr.) Urban

Common name: Burr medic

Family: Fabaceae

Origin:

Native of Europe.

Habit:

Annual herb with creeping stems.

Habitat:

Common weed of tended areas often grows in lawns.

General description:

Stems and leaves

Stems are prostrate, slightly hairy. The compound leaves are clover- like with three inverted heart-shaped leaflets, 0.5-2 × 0.3-1.5 cm, with slightly serrated margins. Leaves are alternate with petioles (leaf stalks) approximately 3 cm long.

Flowers and fruit

Between two and ten small yellow pea flowers (3-6 mm long) are borne on short flower stalks. Fruits are coiled pods 4-6 mm in diameter. There are two varieties of this species which can be distinguished by fruit characteristics. In one the fruits are spiny and less coiled (1.5-3.5 coils), the other has spineless, more coiled (3-6 coils) fruits. The spiny-fruited type flowers from late winter to early summer, while the spineless-fruited type flowers in spring.

Distinguishing characteristics:

Annual herb with creeping stems, with alternate clover-like leaves and spikes of small yellow pea flowers. Fruits are distinctively coiled pods of two types. The spiny-fruited variety is more widespread and is known by the common name ‘burr medic’. A spineless-fruited type is much rarer.

Noxious status:

Not noxious.

Sources:

Kleinschmidt, H.E., Holland, A. and Simpson, P. (1996). Suburban Weeds. 3rd Edition. Department of Primary Industries, Brisbane.

Stanley, T.E. and Ross, E.M. (1983-1989). Flora of South-eastern Queensland. Volume 1. Department of Primary Industries, Brisbane.