burr medic

Medicago polymorpha
Herb
Alternate
Compound
Yellow
Green

Burr medic (Medicago polymorpha) has hairless (i.e. glabrous) stems and leaves. Its flowers are borne in small clusters, each containing 2-10 flowers. The coiled fruit (4-11 mm across) are covered in slender spines, or they are occasionally spineless and have a bumpy (i.e. tuberculate) surface.

Common names 
Also known as: burr medic, bur clover, California bur-clover, hairy medic, spiny burr medic, toothed bur clover,
Family 
Fabaceae
Deciduous 
No
Flowering time 
Year round
Native/Exotic 
Exotic
Origin 
Native to northern Africa, the Azores, the Madeira Islands, the Canary Islands, Europe, western Asia and the Indian sub-continent.
Notifiable 
No
Council declaration 
SIL – Special Investigation List
Known distribution 

Widely naturalised throughout most of the country, but most common in southern and eastern Australia. Common in southern and central Queensland, New South Wales, the ACT, Victoria, Tasmania, southern South Australia and south-western Western Australia.

Habitat 

A common weed of crops, pastures, riparian vegetation, revegetation areas, roadsides, disturbed istes, waste areas, parks, footpaths, gardens, lawns and other turfed areas.

Habit 

A short-lived (i.e. annual) herbaceous plant with creeping (i.e. prostrate) or spreading (i.e. decumbent) stems.

Impact and control methods 

Burr medic (Medicago polymorpha) is regarded as an environmental weed in Victoria, New South Wales and Western Australia.

Stem and leaves 

"The slender green stems are practically hairless (i.e. sub-glabrous).

The alternately arranged leaves are once-compound with three leaflets (i.e. trifoliate) and are borne on stalks (i.e. petioles) about 30 mm long. The leaflets (5-25 mm long and 3-23 mm wide) are egg-shaped in outline (i.e. obovate) or almost heart-shaped (i.e. cordate). They are almost hairless (i.e. glabrate) and have slightly toothed (i.e. dentate) margins."

Flowers and fruits 

"The small pea-shaped flowers (3-6 mm long) are arranged in small clusters (2-10) in the upper leaf forks (i.e. axils). Each of these yellow flowers are borne on short stalks (i.e. pedicels). Flowering occurs from late winter through to early summer.

The fruit are coiled pods (4-10 mm across) and they are usually adorned with many slender spines or prickles (2-3 mm long). However, the spines may be reduced to small bumps in some forms of this species. Each pod contains several, brown, kidney-shaped (i.e. reniform), seeds."

Similar species 

"Burr medic (Medicago polymorpha) may be easily confused with cut-leaved medic (Medicago lacinata), woolly burr medic (Medicago minima), barrel medic (Medicago truncatula), spotted medic (Medicago arabica), black medic (Medicago lupulina) and yellow suckling clover (Trifolium dubium ). These species can be distinguished by the following differences:

■burr medic (Medicago polymorpha) has hairless (i.e. glabrous) stems and leaves. Its flowers are borne in small clusters, each containing 2-10 flowers. The coiled fruit (4-11 mm across) are covered in slender spines, or they are occasionally spineless and have a bumpy (i.e. tuberculate) surface.

cut-leaved medic (Medicago lacinata) has hairless (i.e. glabrous) or sparsely hairy (i.e. puberulent) stems and leaves. Its leaflets are deeply and irregularly toothed. The flowers are borne in small clusters, each containing only 2-3 flowers, and its strongly coiled fruit (7-11 mm across) are covered in stiff spines.

woolly burr medic (Medicago minima) has hairy or densely hairy (i.e. pubescent) stems and leaves. Its flowers are borne in small clusters, each containing 3-6 flowers, and its coiled fruit (6-10 mm across) are covered in slender, hooked, spines.

barrel medic (Medicago truncatula) has hairy (i.e. pubescent) stems and leaves. Its flowers are borne singly or in small clusters, containing only 2-3 flowers, and its strongly coiled fruit (about 10 mm across and with 3-7 coils) are covered in short thick spines.
spotted medic (Medicago arabica) has hairless (i.e. glabrous) or slightly hairy (i.e. puberulent) stems and leaves. Its leaflets usually have a large reddish-brown coloured spot in the centre. The flowers are borne singly or in small clusters, containing 2-5 flowers, and its coiled fruit (about 10 mm across) are covered in slender curved spines.

black medic (Medicago lupulina) has sparsely hairy to hairy (i.e. puberulent to pubescent) stems and leaves. Its flowers are borne in dense, many-flowered, clusters and its tiny fruit (about 2 mm long) are not coiled. These fruit are spineless and usually turn black in colour when mature.

yellow suckling clover (Trifolium dubium ) has hairless (i.e. glabrous) stems and leaves. Its flowers are borne in small dense clusters, containing several flowers, and its tiny fruit (about 2 mm long) are not coiled. These fruit are spineless and remain enclosed by the remains of the flower (i.e. the calyx) when mature."