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Centaurea eriophora

Description
 

Mallee Cockspur (Centaurea eriophora) is an annual herb with erect, widely branched, stems to 40 cm (sometimes up to 70) cm tall, winged in the upper part. Initially it forms a prostrate rosette with stalked, deeply lobed leaves, more or less lanceolate in outline with venation prominent on the underside, to 12 cm long. Stem leaves are oblong-lanceolate becoming narrower up the stem, toothed to entire and mucronate (terminating in a point), hairy and sparsely cobwebby below. These leaves extend along the stem forming wings in the upper part.

The flowerheads are solitary, terminal to the stems, surrounded by the upper leaves, 15-20 mm diameter, ovoid-globose in shape. Flowering heads may also occur in the branch junctions. The outer floral bracts (modified leaves surrounding the flower head) are densely cobwebby to woolly, each with a single terminal spine to 15-26 mm long, and 3 very short lateral spines to 5 mm long on each side of the long spine and at right angles to it. The median floral bracts have a shorter central spine and reduced lateral spines and little woolliness while inner floral bracts lack spines and are hairless. The floral bracts surround many yellow, slender, tubular, glandular flowers. Each flower can produce 1 seed (achene) which is slightly flattened, shiny brownish grey, very sparsely hairy and about 4-4.5 mm long and 2.3 mm wide. The base of the achene is attached obliquely to the receptacle and with an ant attracting eliasome (an outgrowth on a seed containing large oil-storing cells) at this point. The apex is surmounted by a pappus of unequal, coarse bristles about 2 - 4.5 mm long, which are minutely barbellate. The receptacle is concave and bears long white bristles 13-14 mm long which surround the developing seeds (Tutin 1976; Jessop & Toelken 1986; Witztum 1989; Witztum et al. 1996).

For further information and assistance with identification of Mallee Cockspur contact the herbarium in your state or territory.

Distribution:

Mallee Cockspur is currently confined to the Murray region of South Australia, in the Sedan/Swan Reach area where it restricted to an area of about 4 hectares (Cunningham & Brown 2006). It is restricted to roadsides and is not in adjacent paddocks (Cooke, pers. comm., 2007). However, a specimen from Wail in the Wimmera district of Victoria collected in 1992 might possibly be this species (National Herbarium of Victoria).

Mallee Cockspur could establish in southern temperate Australia including the southern parts of Western Australia, South Australia and Victoria, New South Wales and Tasmania (Cunningham & Brown 2006).

Mallee Cockspur is also naturalised in Israel, California and Colorado, in the United States (Cunningham & Brown 2006).

Habit:Herb
Key points:
  • Infestations of Mallee Cockspur (Centaurea eriophora) are currently small but the species has potential to spread widely in climatically suitable dryland cropping areas of south-eastern and south-western Australia.
  • It is likely to be a prolific seed producer but is probably not wind-dispersed.
  • Mallee Cockspur is palatable to grazing livestock and should not become a serious pasture weed.
How it spreads:

Mallee Cockspur is likely to be a prolific seeder like closely related species (Cunningham & Brown 2006). The seeds (achenes) of Mallee Cockspur are not readily wind dispersed despite having a persistent pappus. Research in Israel has shown that seeds of Mallee Cockspur where not blown away by winds whereas the lighter seeds of the related Centaurea hyalolepis and the heavier but hairier seeds of C. crocodylium were blown away. The coarse pappus bristles of Mallee Cockspur cause the seeds to cling to the ground or move slightly upwind on the ground (Witztum et al. 1996).

The eliasome (an outgrowth on a seed containing large oil-storing cells) found on the base of the seeds of Mallee Cockspur is attractive to ants and probably acts to aid very local dispersal (Witztum et al. 1996).

The coarse pappus bristles may also aid dispersal by clinging to animals or machinery, similarly to other thistle species.

Where it grows:

Mallee Cockspur occurs in areas with a Mediterranean climate. In South Australia it has been found only on roadsides in dryland cropping and pasture areas, not in adjacent crops and pastures. The species is palatable and readily grazed by livestock hence its absence from pastures, and the normal herbicide applications in cropping areas apparently account for its absence from crops (Tutin 1976; Jessop & Toelken 1986; Witztum 1989; Cooke 2007, pers. comm.).

Flower colour:Yellow
Distribution map:

Cunningham & Brown (2006).

Impacts:

Mallee Cockspur is one of seventeen sleeper weeds identified by the Bureau of Rural Sciences (following consultation with the Australian Weeds Committee) which could have nationally significant impacts on agriculture if allowed to spread.

Dryland cropping and grazing are the land uses potentially at risk from spread of Mallee Cockspur (CSIRO 2002). Irrigated and rotational grazing pastures and amenity areas are currently impacted by the South Australian infestations (Cooke, pers. comm. in Cunningham & Brown 2006).

Origin:

Mallee Cockspur is native to southern and south-eastern Spain and Portugal where it is found on roadsides and cultivated land (Tutin 1976). In Israel it has been recorded as present but not fully naturalised in "neglected public areas" and is also known to occur in north Africa in Morocco and Algeria (Witztum 1989).

History:

Mallee Cockspur was first recorded in Australia in 1984 being collected from a road reserve near Sedan, South Australia (Jessop & Toelken 1986; Cooke 2007, pers. comm.). The means of introduction is unknown but is probably accidental (Groves & Hosking 1998).

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This database is designed to provide information, including biological and ecological, on invasive plant species that are on a national weed list, or are legislated against in a state or territory. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. For further information on the images contained in the database please contact the copyright owner. All images in the weed identification tool are managed by the Australian Plant Image Index (APII). Various copyright conditions apply for these images. For further information on the copyright conditions of images contained in the database please contact the APII at: photo@anbg.gov.au.