Stinking Mayweed

Anthemis cotula L.

Synonyms - Maruta cotula

Family: Asteraceae

Names:

Anthemis is from the Greek anthemon meaning flower.
Cotula is from the Latin, referring to a measuring cup of about 300 mL and alludes to the cup shaped flower head.
Stinking Mayweed - refers to the smell of the plant and its period of rapid growth in May in Europe.

Other Names:

Balders
Chigger Weed
Dillweed
Dog's Chamomile
Dog Daisy
Dog Fennel
Dog Finkle
Hog's Fennel
Fetid Chamomile
Mather
Mayweed
Maise
Morgan
Pig Sty Daisy
Stinking Chamomile

Summary:

300-600 mm tall annual with branched stems, finely divided leaves, an unpleasant smell and white daisy like flowers with a yellow centre.

Description:

Cotyledons:

Two. The cotyledon is small, about 4 mm long, oval and sessile.

First leaves:

The first leaves are pinnate, and as the plant grows the leaflets become progressively more divided.

Leaves:

Alternate. Divided. Dull green.
Stipules -
Petiole - Usually none.
Blade - Egg shaped, 15-60 mm long x 10-25 mm wide, a few hairs, finely divided twice into parallel sided segments. Segments are 1.5-7 mm long x 1 mm wide. Fetid odour and acrid taste.

Stems:

Erect, slender, many branched from the base, striped, almost hairless. 200-600 mm long. Strong disagreeable smell when crushed. Bitter taste.
Flower stem - Leafless.

Flower head:

Single(involucre) on leafless stalks, hemispherical, Daisy-like, composite with yellow disc florets surrounded by a ring of ray florets with white ligules.

Flowers:

The 'flower' is 15- 35 mm overall in diameter.
Bracts - About 3 rows of oblong bracts underneath have a obvious green stripe, pointed tips and soft sparse to woolly hairs.
Ovary -
Florets - Ray florets are in a single row or 10-18 in a conical disk, white, oblong, 5-11 mm long, sterile (and have no styles), 3 toothed at the top and bent back.
Disk florets are numerous, yellow, tubular and bisexual.
Receptacle - becomes conical and scaly at maturity
Petals - white.
Stamens -
Anthers -

Fruit:

Seeds:

Red brown, 1-2 mm long x 1-2 mm wide, cylindrical, usually 10 ribbed, roughly warty and have no pappus

Roots:

Short thick crown with many branching fibrous roots to 500 mm deep.

Key Characters:

Biology:

Life cycle:

Annual. Seeds germinate at any time of the year with a flush in autumn and spring. Flower stems appear in spring and flowering occurs from November to April. The plant dies off in autumn.

Physiology:

Reproduction:

By seed.

Flowering times:

November to January or autumn.

Seed Biology and Germination:

Seed germinates at any time moisture is available. Seed production varies from 500 to 12,000 per plant. Many are infertile. Some are dormant due to a hard seed coat of larger seeds. Buried seed may remain viable for 25 years. Germination is improved by alternating temperatures with maximum germination occurring when night temperatures are between 10 and 15 degrees C and day temperatures of 20 to 27 degrees C.

Vegetative Propagules:

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Reproduction is by means of seed. Most spread can be attributed to the movement of contaminated hay, chaff, produce and pasture seeds. It is also spread in soil or mud, carried by animals or vehicles, and in water.

Origin and History:

Europe. North and West Africa. Mediterranean. South west Asia.
Probably introduced into Australia soon after settlement. Records of its weediness date back to 1523 in Europe.

Distribution:

ACT, NSW, QLD, SA, TAS, VIC, WA.
Occasional patches of this species are found in the north and north-west of Tasmania.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Humid to semi arid temperate regions.

Soil:

Tolerates a wide range of soils.
Prefers heavy clays and clay loams.

Plant Associations:

Significance:

Beneficial:

Fodder.

Detrimental:

Weed of disturbed areas, annual crops, roadsides, gardens, around farm yards and occasionally an invasive species in pasture.
In Europe, Mayweeds are important weeds in cereal crops.
Taints dairy products and meat.

Toxicity:

Probably toxic to poultry. Causes skin blisters and dermatitis after prolonged contact with the flower heads. Suspected of causing staggers in calves.

Symptoms:

Dermatitis, skin blisters.
Staggers.

Treatment:

Remove source of irritation.

Legislation:

Secondary noxious weed of Tasmania.

Management and Control:

Control is often difficult because there are a range of plants at different growth stages.

Thresholds:

Eradication strategies:

Remove odd plants by hand before seed is set. Cultivate larger patches and repeat as required. There are number of selective herbicides for use in cereal crops.
Establish a vigorous perennial pasture and spot spray individual plants. Apply adequate fertiliser and don't overgraze.

Herbicide resistance:

Biological Control:

Related plants:

Common Chamomile (Anthemis nobilis = Chamaemelum nobile)
Corn Chamomile (Anthemis arvensis) is similar but has no odour.

Plants of similar appearance:

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P83-84. Photo.

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P877.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P672.

Gardner, G.A. and Bennetts, H.W. (1956). The toxic plants of Western Australia. (West Australian Newspapers Ltd, Perth). P194.

Hyde-Wyatt, B.H. and Morris, D.I. (1975). Tasmanian weed handbook. (Tasmanian Department of Agriculture, Hobart, Tasmania). P92-93. Diagram.

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). #99.2.

Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious weeds of Australia. (Inkata Press, Melbourne). P254. Photos.

Acknowledgments:

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