Carduus pycnocephalus L., Asteraceae

Click on an image for links to BIGGER PICTURES

Present on Pacific Islands?  yes

Primarily a threat at high elevations?  yes

Common name(s): [more details]

English: Italian plumeless thistle, Italian thistle, compact-headed thistle, sheep thistle, shore thistle, slender thistle, slender winged thistle, slender-flower thistle, winged slender thistle, woolly thistle

Habit:  herb

Description:  "Annual herbs 5-10 dm tall; stems arachnoid pubescent, spiny-winged throughout.  Leaves oblanceolate to oblong-lanceolate, upper surface sparsely pubescent, lower surface arachnoid-woolly, 8-25 cm long, 2.5-6 cm wide, pinnatifid, with 2-5 pairs of lobes, margins spiny, the spines up to 12 mm long, base decumbent for entire internode.  Heads 1-3 in clusters; involucre cylindrical, 1.5-2 cm long, 0.7-1.3 cm in diameter, arachnoid pubescent, the outer bracts spine-tipped, the inner ones up to 1.3 times as long as the middle ones, faintly 3-nerved, attenuate; corollas purple, 10-14 mm long; pappus 10-14 mm long.  Achenes 4-5 mm long, compressed, smooth"  (Wagner et al., 1999; p. 284).

Habitat/ecology:  "Grassland, scrub, woodland, disturbed places.  In the native range, this highly variable species grows on stony hillslopes, in coastal scrub and disturbed places.  Once established where introduced, it can become dominant and exclude native species.  In savannas, it can carry grass fires to tree canopies and thus increases fire hazards"  (Weber, 2003; p. 85).

In Hawai‘i, "naturalized in dry sites, 1,340-2,130"  (Wagner et al., 1999; p. 284).

Propagation:  Seed.  Fruit production is prolific and the long-lived seeds may remain viable up to 10 years  (Weber, 2003; p. 85).

Native range:  Europe (Wagner et al., 1999; p. 284).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Chile (offshore islands) Rapa Nui (Easter) Island	Rapa Nui (Easter) Island (Isla de Pasqua)	introduced cultivated	Meyer, Jean-Yves (2008) (pp. 40, 41) "Lefeuvre et al., 2005. Nous n’avons pas vues lors de cette" (Meyer, 2008).
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive	Cuevas, Jaime G./Marticorena, Alicia/Cavieres, Lohengrin A. (2004) (p. 535) Voucher cited: JF 63
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive	Atkinson, Rachel/Sawyer, John (2011)
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive	Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido (2006) (p. 552)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 284) Voucher cited: Wagner 5657 (BISH)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	New South Wales	introduced invasive	National Herbarium of New South Wales (2013) Naturalised
Australia Australia (continental)	Australia (continental)	introduced invasive	National Herbarium of New South Wales (2013) Tasmania, Victoria, Western Australia Naturalised
Australia Australia (continental)	Queensland	introduced invasive	National Herbarium of New South Wales (2013) Naturalised
Japan Japan	Japan	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 189)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 300) "Waste land, pasture, riverbeds, roadsides, railway yards, tussock grassland".
South America (Pacific rim) South America (Pacific rim)	Chile (Republic of)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
United States (west coast) United States (west coast states)	USA (Oregon)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
United States (west coast) United States (west coast states)	USA (California)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
United States (continental except west coast) United States (other states)	United States (other states)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized

Control:  Additional control information from the Bugwood Wiki.

Physical:  "Hand pulling is possible, but the root must be cut at least 10 cm below ground level to prevent regrowth.  Mowed plants can regrow fast and still produce seeds.  Grazing by sheep or goats has been proved to be effective".

Chemical:  "Chemical control is done by herbicides containing glyphosate, picloram, or 2,4-D"  (Weber, 2003; p. 85).