Woolly Burr Medic

Medicago minima (L.) Bartal.

Family: Fabaceae.

Names:

Medic is from the Latin medica meaning Lucerne and derived from the Greek mediche because it was introduced to Greece from the Media region in the Old Persian Empire.
Woolly Burr Medic because the burr has woolly hairs beneath the spines.

Other names:

Clover Burr
Goldfields Medic
Kalgoorlie Clover
Little Burr Clover
Little Medic
Small Medic
Small Woolly Burr Medic
Woolly Burr
Woolly Trefoil

Summary:

A low growing, hairy trifoliate leaved, annual herb with small yellow flowers in clusters of 1 to 8 flowers in winter to spring and a dark brown, spiny, spiralled burr with 3-5 loose coils.

Description:

Cotyledons:

Two. Oval. Hairless. Tip round. Sides convex. Base tapered to squarish. Surface hairless. No petiole.

First leaves:

First leaf is kidney shaped with small hairs on both surfaces and a round tip with a small point. Later leaves have 3 leaflets with toothed tips and the centre leaflet on a longer stalk. The leaflets and petioles have small hairs. The leaflets may be heart shaped on the early leaves rather than egg shaped.

Leaves:

Alternate. Set of 3 leaflets, on short stalks. End leaflet has a slightly longer stalk than the 2 on the sides. Greyish green due to dense hairs.
Stipules - Egg shaped, 3-7 mm long. Tip pointed. Edges smooth or with small teeth near the base. Attached to petiole.
Petiole - Yes.
Blade - Leaflets grey-green, egg shaped to wedge shaped, 3-10 mm long x 2-7 mm wide. Edges with small, rounded or pointed teeth near the tip. Tip rounded, pointed, with 3 teeth or notched. Mid-vein often reddish. Densely hairy on both surfaces.

Stems:

Greyish, erect or low lying or with the ends bending upwards, 50-300 mm long, square in cross section. Densely and softly hairy. Simple and occasionally glandular hairs.

Flower head:

Arise from leaf axils in sets of 1-8 flowers. On an awned stalk 8-12 mm long. Axillary raceme.

Flowers:

Pea type, yellow.
Bracts - Small, persistent.
Ovary -
Calyx - Tubular. Tube is 1.5-2 mm long, hairy with 5 awl shaped lobes that are 1.5-2 mm long.
Petals - Yellow. Standard, 3-4 mm long x 2 mm wide, egg shaped. Limb egg shaped. Wings 3 mm long. Keel 3 mm long.
Stamens - 9 in a group and 1 alone.
Anthers -

Fruit:

Dark brown, cylindrical to almost globular, spiny pod with 3-5 loose coils, 2-5 mm high by 3-5 mm diameter excluding the spines. Hairy beneath the spines. Faint lines on pod. Spines are 3-4 mm long, thin, erect, almost at right angles to each other, hooked at the tip and grooved towards the base. Seam on the back is narrow with 2 almost flat, deep, parallel furrows. Valves have inconspicuous or faint network pattern on the surface.

Seeds:

1.5-3 mm long, kidney shaped. 4-8 seeds per pod. Surface smooth and hairless.

Roots:

Have nitrogen fixing nodules.

Key Characters:

Annual.
Cotyledons oval shaped.
First leaf kidney shaped.
Older leaves trifoliate with the terminal leaflet on a longer petiolule than the side leaflets.
Yellow pea type flowers.



Barrel shaped, tightly coiled, flat ended, cylindrical pod with spines. The spines are slightly grooved near the base. The transverse nerves terminating in a nerve parallel to and on each side of the dorsal suture on the pod. Stipules entire or with very small teeth. Leaflets denticulate towards apex only, not lobed, and densely hairy above and below. Spines of pod uncinate (hooked at the tip).
From Black, 1977, Marchant, 1987 and John Moore.

Biology:

Life cycle:

Annual. Germinates in autumn and winter. Flowers from late winter to spring. Dies with the onset of summer drought.

Physiology:

Drought tolerant.
Requires high phosphate levels for maximum growth.

Reproduction:

By seed.

Flowering times:

Spring to early summer in western NSW.
September to November in SA.
July to September in Perth.
Winter and spring in WA.

Seed Biology and Germination:

Produces dormant or hard seed.

Vegetative Propagules:

None.

Hybrids:

A number of varieties exist. Var. brachyodon has the spines reduced to broad teeth that are only slightly longer than the seam on the back of the 2.5-3 coiled pod and the hairs are often glandular.

Allelopathy:

Population Dynamics and Dispersal:

Spread mainly by burrs attaching to passing animals and distributing seed.

Origin and History:

Europe. Western Asia. Mediterranean. Canary Islands. Northern Africa.

Distribution:

ACT, NSW, NT, QLD, SA, TAS, VIC, WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Temperate. Mediterranean.

Soil:

Most abundant on sands and sandy loams.
Occasionally on clays, gilgai puffs, river flood plains.
Granite outcrops.

Plant Associations:

In many communities.

Significance:

Beneficial:

Palatable fodder but production is poor.
Burrs provide protein in the dry season.
Tolerant of rotational cropping.
Fixes nitrogen.

Detrimental:

Weed of roadsides, disturbed areas, pastures, turf, native woodlands, recreational areas and fallows.
Burrs cause vegetable fault in wool.

Toxicity:

Occasionally toxic causing photo sensitisation referred to as trefoil dermatitis, clover sickness or trifoliosis in sheep, cattle and horses.

Symptoms:

Dermatitis with no jaundice. Rarely fatal.

Treatment:

Remove stock from infestation.

Legislation:

None.

Management and Control:

Thresholds:

In cropping situations, 20-50 plants/m2 are often worth controlling.

Eradication strategies:

Exclude stock to prevent dispersal of burrs.
Hand pull odd plants in winter before flowering. For small infestations and grass dominant areas an annual application of 1 L Tordon® 75-D® to 100 L water in early winter gives excellent control of existing plants and has residual activity to control seedlings. In bushland, 500 mL/ha Lontrel® or 50 g/ha Logran® applied in early winter provides reasonably selective control. Repeat annually for several years. Plant tall growing perennial species to reduce re invasion. It is relatively tolerant to glyphosate, grazing and mowing.
Other sulfonylurea herbicides also provide good control.

Herbicide resistance:

It is relatively tolerant to glyphosate.

Biological Control:

Related plants:

Barrel Medic. (Medicago truncatula)
Black Medic (Medicago lupulina)
Burr Medic (Medicago polymorpha, Medicago hispida)
Button Medic (Medicago orbicularis)
Calvary Medic (Medicago intertexta)
Cutleaf Medic (Medicago laciniata)
Disc Medic (Medicago tornata)
Gama Medic (Medicago rugosa)
Lucerne (Medicago falcata ssp. sativa)
Lucerne (Medicago sativa)
Murex Medic (Medicago murex)
Small leaved Burr Medic (Medicago praecox)
Snail Medic (Medicago scutellata)
Spotted Medic (Medicago arabica)
Strand Medic (Medicago littoralis)
Woolly Burr Medic(Medicago minima)
Yellow Lucerne (Medicago falcata)

Plants of similar appearance:

Clovers (Trifolium species) usually have the central leaflet on a stalk the same length as the side leaflets.
Melilotus species
Oxalis species usually have a bitter taste.
Trefoils

References:

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P460.

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P224. Diagram of seed pod.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P402. Photo.

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P471.

Gardner, G.A. and Bennetts, H.W. (1956). The toxic plants of Western Australia. (West Australian Newspapers Ltd, Perth). P106.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P154. Photo.

Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #806.10.

Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P284.

Wilding, J.L. et al. (1987). Crop weeds. (Inkata Press, Melbourne). P104. Diagrams. Photos.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.