''Carduus'' is a genus of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

s in the family

Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...

, and the tribe

Cardueae The Cardueae are a tribe of flowering plants in the daisy family (Asteraceae) and the subfamily Carduoideae. Most of them are commonly known as thistles; four of the best known genera are '' Carduus'', '' Cynara'' (containing the widely eaten ar ...

, one of two genera considered to be true thistles, the other being '' Cirsium''. Plants of the genus are known commonly as plumeless thistles.''Carduus''.
Integrated Taxonomic Information System (ITIS).''Carduus''.
Flora of North America. They are native to Eurasia and Africa, and several are known elsewhere as

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 there ...

. This genus is noted for its disproportionately high number of

noxious weed A noxious weed, harmful weed or injurious weed is a weed that has been designated by an agricultural or other governing authority as a plant that is injurious to agricultural or horticultural crops, natural habitats or ecosystems, or humans or liv ...

s compared to other flowering plant genera.

Etymology

The genus name ''Carduus'' is from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

for "a kind of thistle"''Carduus''.
The Jepson eFlora 2013. or "thistlelike plant". It is related to the word ''Cardonnacum'' ("a place of chardons or thistles"), which is the origin of

Chardonnay Chardonnay (, , ) is a green-skinned grape variety used in the production of white wine. The variety originated in the Burgundy wine region of eastern French wine, France, but is now grown wherever wine is produced, from English wine, Englan ...

, the name of the

grape variety This list of grape varieties includes cultivated grapes, whether used for wine, or eating as a table grape, fresh or dried (raisin, currant, sultana). For a complete list of all grape species including those unimportant to agriculture, see Viti ...

. It is also related to the word ''card'', which as a noun means a device (often a stiff-bristled brush) for aligning and cleaning fibers, and as a verb means the action of processing fibers in that way.

Description

These are usually annual or biennial herbs, sometimes perennial. Species often grow 2 meters in height but are known to reach 4 meters. The erect stems are winged and spiny, and usually have woolly hairs. The leaf blades are hairy to hairless and entire or divided into lobes, and they have spine-toothed edges. The

flower heads A pseudanthium (Greek for "false flower"; ) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, compos ...

are solitary or borne in

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

s of up to 20. The head is spherical to cylindrical and covered in several layers of spreading or curving spine-tipped phyllaries. It contains long, tubular disc florets in shades of white, pink, or purple. The fruit is a cypsela tipped with a pappus of barbed bristles or scales.

Ecology

Several ''Carduus'' are notorious invasive plants outside their native range, for example, in

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

and the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

.Genus ''Carduus''.
Encycloweedia. California Department of Food and Agriculture. Species such as ''C. acanthoides'', ''C. nutans'', ''C. pycnocephalus'', and ''C. tenuiflorus'' easily become weedy in disturbed habitat, such as

overgrazed Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, game reserves, or nature rese ...

pasture. ''C. nutans'' is

allelopathic Allelopathy is a biological phenomenon by which an organism produces one or more biochemicals that influence the germination, growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have ben ...

, producing compounds that inhibit the growth and development of other plants. Agents of

biological pest control Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also invo ...

that have been used against weedy ''Carduus'' thistles include the thistle head weevil (''Rhinocyllus conicus''), thistle crown weevil (''Trichosirocalus horridus''), and thistle crown fly (''Cheilosia corydon''). The musk thistle rust (''Puccinia carduorum''), a

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

, may also be used against ''C. nutans''.

Diversity

File:20130413Carduus acanthoides1.jpg, '' Carduus acanthoides'' File:Partially opened flower bud of Carduus nutans.jpg, ''

Carduus nutans ''Carduus nutans'', with the common names musk thistle, nodding thistle, and nodding plumeless thistle, is a biennial plant in the daisy and sunflower family Asteraceae. It is native to regions of Eurasia. Description ''Carduus nutans'' is usual ...

'' File:1398 - Nationalpark Hohe Tauern - Flowers.JPG, '' Carduus personata'' File:Carduus Keniensis.jpg, ''

Carduus keniensis ''Carduus'' is a genus of flowering plants in the family Asteraceae, and the tribe Cardueae, one of two genera considered to be true thistles, the other being ''Cirsium''. Plants of the genus are known commonly as plumeless thistles.

'' There are about 90 to 127''Carduus''.
The Plant List. species in the genus. Species include: *'' Carduus acanthocephalus'' *'' Carduus acanthoides'' – spiny plumeless thistle *''

Carduus acicularis ''Carduus argentatus'', sometimes known as the silver thistle, is an annual herb in the family Asteraceae. As a member of the genus ''Carduus'' it is known as a plumeless thistle.Carduus adpressus'' *'' Carduus affinis'' *''

Carduus afromontanus ''Carduus'' is a genus of flowering plants in the family Asteraceae, and the tribe Cardueae, one of two genera considered to be true thistles, the other being ''Cirsium''. Plants of the genus are known commonly as plumeless thistles.

'' *'' Carduus amanus'' *'' Carduus angusticeps'' *'' Carduus arabicus'' *''

Carduus argentatus ''Carduus argentatus'', sometimes known as the silver thistle, is an annual herb in the family Asteraceae. As a member of the genus ''Carduus'' it is known as a plumeless thistle.Carduus argyroa ''Carduus'' is a genus of flowering plants in the family Asteraceae, and the tribe Cardueae, one of two genera considered to be true thistles, the other being '' Cirsium''. Plants of the genus are known commonly as plumeless thistles.

'' *'' Carduus asturicus'' *'' Carduus aurosicus'' *'' Carduus axillaris'' *'' Carduus baeocephalus'' *'' Carduus ballii'' *'' Carduus bourgaei'' *'' Carduus bourgeanus'' *'' Carduus broteroi'' *'' Carduus budaianus'' *'' Carduus candicans'' *'' Carduus carduelis'' *'' Carduus carlinoides'' *'' Carduus carpetanus'' *'' Carduus cephalanthus'' *'' Carduus chevallieri'' *'' Carduus chrysacanthus'' *'' Carduus clavulatus'' *'' Carduus corymbosus'' *'' Carduus collinus'' *'' Carduus crispus'' – curly plumeless thistle, curled thistle, welted thistle *'' Carduus dahuricus'' *'' Carduus defloratus'' *'' Carduus edelbergii'' *'' Carduus euboicus'' *'' Carduus fallax'' *'' Carduus fasciculiflorus'' *'' Carduus fissurae'' *'' Carduus getulus'' *'' Carduus hamulosus'' *'' Carduus hazslinszkyanus'' *'' Carduus hohenackeri'' *'' Carduus ibicensis'' *'' Carduus jordanii'' *'' Carduus juratzkae'' *''

'' *'' Carduus kerneri'' *'' Carduus kirghisicus'' *'' Carduus knorringianus'' *'' Carduus kumaunensis'' *'' Carduus lanuginosus'' *'' Carduus leptacanthus'' *'' Carduus leptocladus'' *'' Carduus litigiosus'' *''

Carduus lobulatus ''Carduus'' is a genus of flowering plants in the family Asteraceae, and the tribe Cardueae, one of two genera considered to be true thistles, the other being ''Cirsium''. Plants of the genus are known commonly as plumeless thistles.

'' *'' Carduus lusitanicus'' *'' Carduus macracanthus'' *'' Carduus macrocephalus'' *'' Carduus malyi'' *'' Carduus maroccanus'' *'' Carduus martinezii'' *'' Carduus membranaceus'' *'' Carduus meonanthus'' *'' Carduus millefolius'' *'' Carduus modestii'' *''

Carduus myriacanthus ''Carduus'' is a genus of flowering plants in the family Asteraceae, and the tribe Cardueae, one of two genera considered to be true thistles, the other being ''Cirsium''. Plants of the genus are known commonly as plumeless thistles.

'' *'' Carduus nervosus'' *'' Carduus nigrescens'' *''

'' – musk thistle, nodding thistle *'' Carduus olympicus'' *'' Carduus personata'' *'' Carduus pycnocephalus'' – Italian thistle, Italian plumeless thistle, compact-headed thistle *'' Carduus ramosissimus'' *'' Carduus schimperi'' (may include ''C. platyphyllus'' and ''C. chamaecephalus'') *'' Carduus tenuiflorus'' – sheep thistle, shore thistle, slender thistle *'' Carduus textorisianus'' Marg. *'' Carduus uncinatus'' *''

Carduus weizensis ''Carduus'' is a genus of flowering plants in the family Asteraceae, and the tribe Cardueae, one of two genera considered to be true thistles, the other being '' Cirsium''. Plants of the genus are known commonly as plumeless thistles.

'' ;Hybrids *'' Carduus × aragonensis'' *'' Carduus × arvaticus'' *'' Carduus × camplonensis'' *'' Carduus × cantabricus'' *'' Carduus × cyrneus'' *'' Carduus × ipe'' *''Carduus keniensis'' × ''C. platyphyllus''Young, T. P. and M. M. Peacock. (1985)
Vegetative key to the alpine vascular plants of Mount Kenya.
''Journal of the East African Natural History Society'' 185, 1–9. *'' Carduus × leridanus'' *'' Carduus'' × ''orthocephalus''

References

External links

*
''Carduus''.
In: Greuter, W. & E. von Raab-Straube. (Eds.) Compositae. Euro+Med Plantbase. 2006.

BioImages: The Virtual Field-Guide (UK). Accessed 2013-02-17. {{Taxonbar, from=Q254502 Asteraceae genera Butterfly food plants Taxa named by Carl Linnaeus