APC (2020). Australian Plant Census, Council of Heads of Australasian Herbaria (CHAH). available at https://biodiversity.org.au/nsl/services/APC . [accessed 26/10/2020]
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Woolly Cockspur (Centaurea eriophora) is an annual or biennial herb initially with deeply lobed leaves in a rosette, then producing an erect widely branched, stems to 400 mm tall, rarely to 800 mm, winged in the upper part. The prostrate rosetted grey leaves are has stalked, deeply lobed, more or less lanceolate (lance shaped) in outline up to 120 mm long, with prominent venation on the underside. Stem are produced with thin lobed grey stem leaves that are oblong-lanceolate (oblong = length a few times greater than width, with sides almost parallel and ends rounded) becoming narrower up the stem, toothed to entire and mucronate (terminating in a small point), hairy and sparsely cobwebby below. These leaves extend along the stem forming wings in the upper part.
Flowers are yellow, arranged in solitary, terminal flower–heads on the end of the stems, and also occur in the branch junctions. Flower-heads are surrounded by floral bracts (modified leaves surrounding the flower head), that are ovoid-globose (globe-shaped). Spines are only produced below the flowers on the outer floral bracts (modified leaves surrounding the flower head) that are densely cobwebby to woolly. A single terminal long spine is produced on each outer floral bracts, each single spine is up to 8-15 mm long, with 3-4 pairs of shorter pinnate spines (lateral spines arranged each side and growing from the main terminal spine), with the lower lateral spine the largest about 3 mm long, reducing in size towards the tip to about 0.5 mm long. 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.
The fruits or 'seeds' (cypselas) are produced from each flower with many flowers per flower-head. Seeds are 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 (tip) is surmounted by a pappus of unequal, coarse bristles, about 2 – 4.5 mm long, which are minutely barbellate. The receptacle (where the flowers and seeds attach) is concave and bears long white bristles 13-14 mm long which surround the developing seeds (Bean et al. 2014; Dostal 1976).
For further information and assistance with identification of Woolly Cockspur contact the herbarium in your state or territory.
Woolly Cockspur (Centaurea eriophora) 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 (Bean et al. 2014; Cooke 2007, pers. comm. Dostal 1976; Witztum 1989).
Woolly Cockspur (Centaurea eriophora) is similar to Maltese Cockspur (C. melitensis) which differs in having glabrous to puberulent (covered with very fine hairs) floral bracts with shorter spines (terminal spine only 6-9 mm long, with only 1-3 pairs of small lateral spines) than those of Woolly Cockspur and smaller (2-3 mm long), pubescent (covered in hairs) seeds (Slee 2007, pers. comm.).
Woolly Cockspur could also be confused with St Barnaby's Thistle (C. solstitialis). However, the floral bracts of St Barnaby's Thistle may be glabrous (hairless) or cobwebbed, its flowers are not glandular and its seeds are only about 2.5 mm long but with a pappus twice that length. The flower-heads of St Barnaby's Thistle appear as spiny as those of Woolly Cockspur but do not seem as densely woolly (Slee 2007, pers. comm.).
The three species mentioned above have yellow flowers and upper stem leaves that form narrow wings. All other species of Centaurea naturalised in Australia have pink, purple or blue flowers (Slee 2007, pers. comm.).
Woolly Cockspur(Centaurea eriophora) is only known from a limited area (AVH 2020)
Agriculture: Woolly Cockspur(Centaurea eriophora) 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 Woolly Cockspur. Irrigated and rotational grazing pastures and amenity areas are currently impacted by the South Australian infestations (Cooke, pers. comm. in Cunningham & Brown 2006).
Native ecosystems: It is not known to occur in native vegetation.
Urban areas: Invade roadsides in agricultural areas.
Woolly Cockspur (Centaurea eriophora) is likely to be a prolific seeder like closely related species (Cunningham & Brown 2006). The seeds (achenes) of Woolly Cockspur are not readily wind dispersed despite having a persistent pappus. Research in Israel has shown that seeds of Woolly Cockspur were 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 Woolly 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 Woolly 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.
Woolly Cockspur was first recorded in Australia in 1984 being collected from a road reserve near Sedan, South Australia (AVH 2020; Cooke 2007, pers. comm.). The means of introduction is unknown but is probably accidental (Groves & Hosking 1998).
Woolly Cockspur (Centaurea eriophora) is a target for eradication (Cunningham & Brown 2006).
Chemical control: Woolly Cockspur is easy to control with repeated yearly applications of herbicides to newly establishing plants (Cooke 2007, pers. comm.). Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au .
Non-chemical control: Physical control: Hand remove isolated or small populations of small plants through winter and early spring.
Woolly Cockspur (Centaurea eriophora) is a winter annual that initially forms a rosette which then elongates to form a branched stem in the spring. The plant flowers and sheds seed by the middle of summer. Late rain, after seeding has apparently finished and senescence of leaves has commenced, may cause additional stem growth and a small amount of leaf growth with smaller flowerheads and smaller seeds (see Ruiz de Clavijo 2002). All flowering collection in South Australia have been made in November.
Woolly Cockspur (Centaurea eriophora) is currently confined to the Murray region of South Australia, in the Sedan/Swan Reach area where it is 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). The most recent known (databased) collection was made in 1996 (AVH 2020), and its current status and distribution in SA is unknown.
In addition, a 1992 collected specimen from Wail in the Wimmera district of Victoria might possibly be this species (AVH 2020).
Woolly Cockspur could establish further in southern temperate Australia including the southern parts of Western Australia, South Australia, Victoria, New South Wales and Tasmania (Cunningham & Brown 2006).
Woolly Cockspur is also naturalised in Israel, as well as California and Colorado, in the United States (Cunningham & Brown 2006).
Woolly Cockspur (Centaurea eriophora) is native to southern and south-eastern Spain and Portugal where it is found on roadsides and cultivated land (Dostal 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 (Bean 2014; Witztum 1989).
Mallee Cockspur, Wild Sandheath (Europe).