''Carduus pycnocephalus'', with common names including Italian thistle, Italian plumeless thistle, and Plymouth thistle, is a species of

thistle Thistle is the common name of a group of flowering plants characterised by leaves with sharp prickles on the margins, mostly in the family Asteraceae. Prickles can also occur all over the planton the stem and on the flat parts of the leaves ...

. It is

native Native may refer to: People * Jus soli, citizenship by right of birth * Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory ** Native Americans (disambiguation) In arts and entert ...

to: the

Mediterranean region In biogeography, the Mediterranean Basin (; also known as the Mediterranean Region or sometimes Mediterranea) is the region of lands around the Mediterranean Sea that have mostly a Mediterranean climate, with mild to cool, rainy winters and wa ...

in southern Europe,

North Africa North Africa, or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in ...

, and

Western Asia Western Asia, West Asia, or Southwest Asia, is the westernmost subregion of the larger geographical region of Asia, as defined by some academics, UN bodies and other institutions. It is almost entirely a part of the Middle East, and includes Ana ...

;

East Europe Eastern Europe is a subregion of the European continent. As a largely ambiguous term, it has a wide range of geopolitical, geographical, ethnic, cultural, and socio-economic connotations. The vast majority of the region is covered by Russia, whic ...

and the

Caucasus The Caucasus () or Caucasia (), is a region between the Black Sea and the Caspian Sea, mainly comprising Armenia, Azerbaijan, Georgia (country), Georgia, and parts of Southern Russia. The Caucasus Mountains, including the Greater Caucasus range ...

; and the

Indian Subcontinent The Indian subcontinent is a list of the physiographic regions of the world, physiographical region in United Nations geoscheme for Asia#Southern Asia, Southern Asia. It is situated on the Indian Plate, projecting southwards into the Indian O ...

. The plant has become an

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...

in other regions, and on other continents, often becoming a noxious weed or invasive species.

Description

A winter annual, ''Carduus pycnocephalus'' stems range from to , and are glabrous to slightly wooly. The multiple stems are winged with spines.U.S. National Park Service: Invasive Non-Native Plants in Sequoia and Kings Canyon National Parks — Italian Thistle
/ref> The plant grows in a rosettes of in diameter, with four to ten lobed

basal leaves A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ...

that are long. Cauline leaves are

tomentose Trichomes (); ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a pl ...

on the underside and contain spines on the lobe tips. Flower heads are 2-5 per cluster, densely matted with cobwebby hairs at the base of the phyllaries and spiny towards the tips. Corollas are pink to purple, approx. .4-.6 in (1-1.4 cm) long, and the fruits are brown to gold, with a bristly, minutely barbed pappus.Bossard, CC., J.M. Randall, and M. Hoshovsky. (eds.)
Invasive Plants of California’s Wildlands
University of California Press, Berkeley, CA; 2000.

Noxious weed

''Carduus pycnocephalus'' has become a noxious weed in Australia,

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

Macaronesia Macaronesia (Portuguese: ''Macaronésia,'' Spanish: ''Macaronesia'') is a collection of four volcanic archipelagos in the North Atlantic, off the coasts of Africa and Europe. Each archipelago is made up of a number of Atlantic oceanic islands ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the ...

, the Arabian Peninsula,

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...

, and North America, especially in much of

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

. It is a C-listed weed by the California Department of Agriculture and a Moderate Invasive Plant rating by the California Invasive Plant Council.Cal-IPC—California Invasive Plant Council species treatment: ''Carduus pycnocephalus''
. accessed 4.8.2013 It favors grasslands, woodlands, and chaparral vegetation types, but is especially prevalent in

oak woodland An oak woodland is a plant community with a tree canopy dominated by oaks (''Quercus spp.''). In terms of canopy closure, oak woodlands are intermediate between oak savanna, which is more open, and oak forest, which is more closed. Although the ...

s in and around the Central Valley. It is found in disturbed areas, often with basaltic soils, fertile soils, or soils with a relatively high pH (> 6.5).

Impacts

Italian thistle can grow densely, crowding out other vegetation with dense rosette 'colonies' in the winter, thereby preventing establishment of

native plants In biogeography, a native species is indigenous to a given region or ecosystem if its presence in that region is the result of only local natural evolution (though often popularised as "with no human intervention") during history. The term is equi ...

. Its spiny leaves, stems, and phyllaries prevent animals from grazing on it and nearby forage.Mattole Restoration Council: Italian Thistle (''Carduus pycnocephalus'')
. accessed 4.8.2013 Its tendency to grow under the canopy of oaks increases the risk of

wildfire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identi ...

damage to the trees, as fire can more easily spread to the canopy.

Control

;Mechanical Mechanical methods can be effective but must be done before the plant sets seed. Additionally, the root must be severed at least below the ground to prevent the plant from regenerating. Mowing and slashing are not reliable as the plant is able to regrow and produce seed even at a height of . ;Biological Biological control agents have limited success with ''Carduus pycnocephalus''. Insects that tested host-specific by the California Dept. of Agriculture and caused significant damage to the reproductive structures of the Italian thistle have not been utilized, due to concerns about possible predation of California's native thistle species. ''Puccinia cardui-pycnocephali'' is a species of

rust Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO( ...

(fungus) apparently exclusive to ''Carduus pycnocephalus''. Other rust species have been found on Italian thistle as well. Grazing by

sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to domesticated ...

goats The goat or domestic goat (''Capra hircus'') is a domesticated species of goat-antelope typically kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of th ...

(not cattle) in Australia has showed promise as well.Bendall 1973 ;Chemical Chemical control can be achieved with a variety of products including:

Clopyralid Clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) is a selective herbicide used for control of broadleaf weeds, especially thistles and clovers. Clopyralid is in the picolinic acid family of herbicides, which also includes aminopyralid, pic ...

glyphosate Glyphosate (IUPAC name: ''N''-(phosphonomethyl)glycine) is a broad-spectrum systemic herbicide and crop desiccant. It is an organophosphorus compound, specifically a phosphonate, which acts by inhibiting the plant enzyme 5-enolpyruvylshik ...

, Diquat,

Picloram Picloram is a systemic herbicide used for general woody plant control. It also controls a wide range of broad-leaved weeds, but most grasses are resistant.

, and 2, 4-D ester. However, caution must be exercised when using these products, and their use is not always appropriate, especially near water surfaces and other sensitive natural

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s. Check with local, regional, and national regulations directing use.

References

External links

USDA Plants Profile: ''Carduus pycnocephalus'' (Italian plumeless thistle)Jepson Manual Treatment — ''Carduus pycnocephalus''''Carduus pycnocephalus'' — CalPhoto gallery
{{Taxonbar, from=Q2700500 pycnocephalus Flora of North Africa Flora of Western Asia Flora of Europe Flora of Afghanistan Flora of Egypt Flora of Greece Flora of the Indian subcontinent Flora of Iran Flora of Iraq Flora of Israel Flora of Italy Flora of Jordan Flora of Libya Flora of Morocco Flora of Palestine (region) Flora of Spain Flora of Switzerland Flora of Ukraine