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Medicago polymorpha L.
Burr Medic

Sp.Pl. 2:779 (1753)
Conservation Code
Not threatened
Naturalised Status
Alien to Western Australia
Name Status

Prostrate or ascending annual, herb, 0.04-0.2 m high, to 0.5 m wide. Fl. yellow, Jan to Feb or May or Jul to Nov. Black, brown, white, yellow or grey sand, ironstone gravel, orange-brown sandy clay, granite. Flood plains, valley slopes,dunes, clay flats, roadsides.

Amanda Spooner, Descriptive Catalogue, 17 August 2007

Scientific Description

Prostrate,spreading or scrambling, herb. Stems terete, not spiny, glabrous; pustules or glands absent. Leaves or phylloclades clearly present, compound, alternate, not continuous with stem, 13-70 mm long, glabrous, flat with flat margins; margins entire, leaflets 3, terminal leaflet present, stalked. Stipules present and persistent to older leaves, 3-9 mm long, without glands, ribless. Calyx not accrescent (?). Corolla NaN (?) mm long, uniformly coloured, yellow. Stamens ten. Fruit not constricted between the seeds, round in cross-section. Flowers in January, February, May, July, August, September, October and November. Occurs in the Northern, Eremaean and South-West Botanical Province, in the Pilbara, Carnarvon, Yalgoo, Murchison, Dampierland, Coolgardie, Avon Wheatbelt, Jarrah Forest, Mallee, Warren, Esperance and Swan Coastal Plain IBRA regions.

C. Hollister and K.R. Thiele, 24 October 2023


IBRA Regions
Avon Wheatbelt, Carnarvon, Coolgardie, Dampierland, Esperance Plains, Geraldton Sandplains, Jarrah Forest, Mallee, Murchison, Nullarbor, Pilbara, Swan Coastal Plain, Warren, Yalgoo.
IBRA Subregions
Cape Range, Eastern Goldfield, Eastern Murchison, Edel, Fitzgerald, Geraldton Hills, Hamersley, Katanning, Lesueur Sandplain, Merredin, Northern Jarrah Forest, Nullarbor Plain, Perth, Pindanland, Recherche, Southern Cross, Southern Jarrah Forest, Tallering, Warren, Western Mallee, Western Murchison, Wooramel.
IMCRA Regions
Central West Coast, Leeuwin-Naturaliste, WA South Coast.
Local Government Areas (LGAs)
Albany, Ashburton, Augusta Margaret River, Bayswater, Broome, Bruce Rock, Bunbury, Busselton, Cambridge, Canning, Capel, Carnarvon, Chittering, Cockburn, Cranbrook, Cunderdin, Dalwallinu, Dandaragan, Denmark, Esperance, Gosnells, Greater Geraldton, Harvey, Irwin, Jerramungup, Joondalup, Kalamunda, Kalgoorlie-Boulder, Lake Grace, Manjimup, Melville, Menzies, Merredin, Mingenew, Mount Magnet, Mount Marshall, Murchison, Murray, Narembeen, Narrogin, Nedlands, Northampton, Nungarin, Perth, Ravensthorpe, Rockingham, Sandstone, Shark Bay, South Perth, Stirling, Subiaco, Wagin, Yalgoo, Yilgarn, York.

Management Notes (for the Swan NRM Region)

Alternative Names. Trefoil, Toothed Medic, Creeping Burr, Medic Burr, Rough Medic.

General Biology. Growth form. Herb. Life form. Annual. Reproduction. Seed. Dispersal. Animals (adhesion). Toxicity. Occasionally toxic to livestock. Seedbank persistence. 5+ years.

Notes. Has a taproot and nitrogen-fixing nodules. Prefers high phosphate levels and is more abundant on heavy alkaline soils. Germinates in autumn to winter, flowers in spring and dies with the onset of summer drought and high temperatures. Produces hard coated dormant seed. Softening of hard seeds occurs during auutmn rather than summer, resulting in fewer seedling losses from false breaks of season.

Additional information. Origin. Mediterranean. History of use/introduction. Pasture, honey production.

Suggested method of management and control. Relatively tolerant to glyphosate, grazing and mowing. Hand pull isolated plants in winter before flowering. Lontrel® at 10 ml/10 L + wetting agent provides effective control in early winter. Otherwise metsulfuron methyl 0.1 g/10 L + wetting agent or 1 g/10 L of Logran® applied in early winter provides reasonably selective control. Repeat annually for several years. Read the manufacturers' labels and material safety data sheets before using herbicides. For further information consult the Australian Pesticides and Veterinary Medicines Authority to determine the status of permits for your situation or state.

Management Calendar

Calendar Type Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Comments
Germination       Y Y Y Y Y Y Y      
Active Growth           Y Y Y Y Y Y    
Flowering         Y Y Y Y Y Y Y    
Fruiting               Y Y Y Y Y  
Herbicide Treatment           Y Y Y          

Legend: Y = Yes, regularly, O = Occasionally, U = Uncertain, referred by others but not confirmed.



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