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.Jordon-Thaden, I. E. and S. M. Louda. (2003). Chemistry of Cirsium and Carduus: a role in ecological risk assessment for biological control of weeds? Biochemical Systematics and Ecology 31(12), 1353-96. 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 temperate Eurasia and North Africa, and several are known elsewhere as introduced species. This genus is noted for its disproportionately high number of noxious weeds compared to other flowering plant genera.Schmidt, J. P. and J. M. Drake. (2011). Why are some plant genera more invasive than others? PLOS One 6(4), e18654.
Etymology The genus name Carduus is from the Latin 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, the name of the grape variety.Chardonnay. Viticultural Information. UC Integrated Viticulture, University of California. 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 are solitary or borne in inflorescences 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 AustraliaCarduus. PlantNET. National Herbarium of NSW, Royal Botanic Garden, Sydney. and the United States. 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 pasture. C. nutans is allelopathic, producing compounds that inhibit the growth and development of other plants.
Agents of biological pest control 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, may also be used against C. nutans.
Species
The genus includes 82 accepted species, and several natural hybrids.
Carduus acanthocephalus Carduus acanthoides – spiny plumeless thistle Carduus acicularis Carduus adpressus Carduus affinis Carduus amanus Carduus angusticeps Carduus × aragonensis Carduus argentatus Carduus argyroa Carduus × arvaticus Carduus asturicus Carduus × atacinus Carduus aurosicus Carduus axillaris Carduus baeocephalus Carduus ballii Carduus × bergadensis Carduus bourgaei Carduus bourgeanus Carduus broteroi Carduus × brunneri Carduus budaianus Carduus × camplonensis Carduus candicans Carduus × cantabricus Carduus carduelis Carduus carlinoides Carduus carpetanus Carduus cephalanthus Carduus chevallieri Carduus chrysacanthus Carduus clavulatus Carduus collinus Carduus corymbosus Carduus crispus – curly plumeless thistle, curled thistle, welted thistle Carduus dahuricus Carduus defloratus Carduus edelbergii Carduus × estivali Carduus × fallax Carduus fasciculiflorus Carduus fissurae Carduus getulus Carduus × gillotii Carduus × grassensis Carduus × grenieri Carduus hamulosus Carduus hazslinszkyanus Carduus hohenackeri Carduus ibicensis Carduus × intercedens Carduus × ipe Carduus × jordanii Carduus kerneri Carduus kirghisicus Carduus kumaunensis Carduus lanuginosus Carduus × leptocephalus Carduus leptocladus Carduus litigiosus Carduus lobulatus Carduus lusitanicus Carduus macrocephalus Carduus malyi Carduus maroccanus Carduus martinezii Carduus membranaceus Carduus meonanthus Carduus × meratii Carduus × mixtus Carduus modestii Carduus × montis-majoris Carduus × moritzii Carduus myriacanthus Carduus nawaschini Carduus nervosus Carduus nigrescens Carduus numidicus Carduus nutans – musk thistle, nodding thistle Carduus olympicus Carduus onopordioides Carduus × orthocephalus Carduus peisonis Carduus personata Carduus poliochrus Carduus × puechii Carduus pumilus Carduus × pycnocephaloformis Carduus pycnocephalus – Italian thistle, Italian plumeless thistle, compact-headed thistle Carduus pycnocephalus subsp. albidus Carduus pycnocephalus subsp. arabicus (synonym Carduus arabicus ) – Arabian thistle Carduus pycnocephalus subsp. breviphyllarius Carduus pycnocephalus subsp. cinereus Carduus pycnocephalus subsp. intermedius Carduus pycnocephalus subsp. pycnocephalus Carduus quercifolius Carduus ramosissimus Carduus rechingerianus Carduus rivasgodayanus Carduus santacreui Carduus × schulzeanus Carduus seminudus Carduus × sepincola Carduus × septentrionalis Carduus solteszii Carduus spachianus Carduus squarrosus Carduus × stangii Carduus tenuiflorus – sheep thistle, shore thistle, slender thistle Carduus × theriotii Carduus thracicus Carduus tmoleus Carduus transcaspicus Carduus × turocensis Carduus uncinatus Carduus × veronensis Carduus × vigoi Carduus volutarioides Carduus × weizensis
Formerly placed here
Afrocarduus afromontanus (as Carduus afromontanus ) Afrocarduus keniensis (as Carduus keniensis ) Carduus keniensis × C. platyphyllusYoung, 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. Afrocarduus kikuyorum (as Carduus kikuyorum ) Afrocarduus leptacanthus (as Carduus leptacanthus ) Afrocarduus macracanthus (as Carduus macracanthus ) Afrocarduus millefolius (as Carduus millefolius ) Afrocarduus nyassanus (as Carduus nyassanus ) Afrocarduus ruwenzoriensis (as Carduus ruwenzoriensis ) Afrocarduus schimperi (as Carduus schimperi ) Afrocarduus silvarum (as Carduus silvarum )
References
External links
Carduus. In: Greuter, W. & E. von Raab-Straube. (Eds.) Compositae. Euro+Med Plantbase. 2006. Carduus (a genus of thistles). BioImages: The Virtual Field-Guide (UK). Accessed 2013-02-17.