Carduus

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.<ref>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.</ref> Plants of the genus are known commonly as plumeless thistles.<ref name=itis>Carduus. Integrated Taxonomic Information System (ITIS).</ref><ref name=fna>Carduus. Flora of North America.</ref> They are native to temperate Eurasia and North Africa,<ref name = powo/> and several are known elsewhere as introduced species.<ref name=fna/> This genus is noted for its disproportionately high number of noxious weeds compared to other flowering plant genera.<ref>Schmidt, J. P. and J. M. Drake. (2011). Why are some plant genera more invasive than others? PLOS One 6(4), e18654.</ref>

Etymology

The genus name Carduus is from the Latin for "a kind of thistle"<ref name=jeps>Carduus. The Jepson eFlora 2013.</ref> or "thistlelike plant".<ref name=fna/> 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.<ref>Chardonnay. Viticultural Information. UC Integrated Viticulture, University of California.</ref> 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.<ref name=fna/>

Ecology

Several Carduus are notorious invasive plants outside their native range, for example, in Australia<ref>Carduus. PlantNET. National Herbarium of NSW, Royal Botanic Garden, Sydney.</ref> and the United States.<ref name=cdfa>Genus Carduus. Encycloweedia. California Department of Food and Agriculture.</ref> 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.<ref name=cdfa/>

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.<ref name=cdfa/>

Species

• 20130413Carduus acanthoides1.jpg

  Carduus acanthoides

• Partially opened flower bud of Carduus nutans.jpg

  Carduus nutans

• 1398 - Nationalpark Hohe Tauern - Flowers.JPG

  Carduus personata

The genus includes 82 accepted species, and several natural hybrids.<ref name = powo/> Template:Div col

• Carduus acanthocephalus Template:Small
• Carduus acanthoides Template:Small – spiny plumeless thistle
• Carduus acicularis Template:Small
• Carduus adpressus Template:Small
• Carduus affinis Template:Small
• Carduus amanus Template:Small
• Carduus angusticeps Template:Small
• Carduus × aragonensis Template:Small
• Carduus argentatus Template:Small
• Carduus argyroa Template:Small
• Carduus × arvaticus Template:Small
• Carduus asturicus Template:Small
• Carduus × atacinus Template:Small
• Carduus aurosicus Template:Small
• Carduus axillaris Template:Small
• Carduus baeocephalus Template:Small
• Carduus ballii Template:Small
• Carduus × bergadensis Template:Small
• Carduus bourgaei Template:Small
• Carduus bourgeanus Template:Small
• Carduus broteroi Template:Small
• Carduus × brunneri Template:Small
• Carduus budaianus Template:Small
• Carduus × camplonensis Template:Small
• Carduus candicans Template:Small
• Carduus × cantabricus Template:Small
• Carduus carduelis Template:Small
• Carduus carlinoides Template:Small
• Carduus carpetanus Template:Small
• Carduus cephalanthus Template:Small
• Carduus chevallieri Template:Small
• Carduus chrysacanthus Template:Small
• Carduus clavulatus Template:Small
• Carduus collinus Template:Small
• Carduus corymbosus Template:Small
• Carduus crispus Template:Small – curly plumeless thistle, curled thistle, welted thistle
• Carduus dahuricus Template:Small
• Carduus defloratus Template:Small
• Carduus edelbergii Template:Small
• Carduus × estivali Template:Small
• Carduus × fallax Template:Small
• Carduus fasciculiflorus Template:Small
• Carduus fissurae Template:Small
• Carduus getulus Template:Small
• Carduus × gillotii Template:Small
• Carduus × grassensis Template:Small
• Carduus × grenieri Template:Small
• Carduus hamulosus Template:Small
• Carduus hazslinszkyanus Template:Small
• Carduus hohenackeri Template:Small
• Carduus ibicensis Template:Small
• Carduus × intercedens Template:Small
• Carduus × ipe Template:Small
• Carduus × jordanii Template:Small
• Carduus kerneri Template:Small
• Carduus kirghisicus Template:Small
• Carduus kumaunensis Template:Small
• Carduus lanuginosus Template:Small
• Carduus × leptocephalus Template:Small
• Carduus leptocladus Template:Small
• Carduus litigiosus Template:Small
• Carduus lobulatus Template:Small
• Carduus lusitanicus Template:Small
• Carduus macrocephalus Template:Small
• Carduus malyi Template:Small
• Carduus maroccanus Template:Small
• Carduus martinezii Template:Small
• Carduus membranaceus Template:Small
• Carduus meonanthus Template:Small
• Carduus × meratii Template:Small
• Carduus × mixtus Template:Small
• Carduus modestii Template:Small
• Carduus × montis-majoris Template:Small
• Carduus × moritzii Template:Small
• Carduus myriacanthus Template:Small
• Carduus nawaschini Template:Small
• Carduus nervosus Template:Small
• Carduus nigrescens Template:Small
• Carduus numidicus Template:Small
• Carduus nutans Template:Small – musk thistle, nodding thistle
• Carduus olympicus Template:Small
• Carduus onopordioides Template:Small
• Carduus × orthocephalus Template:Small
• Carduus peisonis Template:Small
• Carduus personata Template:Small
• Carduus poliochrus Template:Small
• Carduus × puechii Template:Small
• Carduus pumilus Template:Small
• Carduus × pycnocephaloformis Template:Small
• Carduus pycnocephalus – Italian thistle, Italian plumeless thistle, compact-headed thistle
  • Carduus pycnocephalus subsp. albidus Template:Small
  • Carduus pycnocephalus subsp. arabicus Template:Small (synonym Carduus arabicus Template:Small) – Arabian thistle
  • Carduus pycnocephalus subsp. breviphyllarius Template:Small
  • Carduus pycnocephalus subsp. cinereus Template:Small
  • Carduus pycnocephalus subsp. intermedius Template:Small
  • Carduus pycnocephalus subsp. pycnocephalus
• Carduus quercifolius Template:Small
• Carduus ramosissimus Template:Small
• Carduus rechingerianus Template:Small
• Carduus rivasgodayanus Template:Small
• Carduus santacreui Template:Small
• Carduus × schulzeanus Template:Small
• Carduus seminudus Template:Small
• Carduus × sepincola Template:Small
• Carduus × septentrionalis Template:Small
• Carduus solteszii Template:Small
• Carduus spachianus Template:Small
• Carduus squarrosus Template:Small
• Carduus × stangii Template:Small
• Carduus tenuiflorus Template:Small – sheep thistle, shore thistle, slender thistle
• Carduus × theriotii Template:Small
• Carduus thracicus Template:Small
• Carduus tmoleus Template:Small
• Carduus transcaspicus Template:Small
• Carduus × turocensis Template:Small
• Carduus uncinatus Template:Small
• Carduus × veronensis Template:Small
• Carduus × vigoi Template:Small
• Carduus volutarioides Template:Small
• Carduus × weizensis Template:Small

Formerly placed here

File:Carduus Keniensis.jpg

Afrocarduus keniensis

• Afrocarduus afromontanus Template:Small (as Carduus afromontanus Template:Small)
• Afrocarduus keniensis Template:Small (as Carduus keniensis Template:Small)
• Carduus keniensis × C. platyphyllus<ref>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.</ref>
• Afrocarduus kikuyorum Template:Small (as Carduus kikuyorum Template:Small)
• Afrocarduus leptacanthus Template:Small (as Carduus leptacanthus Template:Small)
• Afrocarduus macracanthus Template:Small (as Carduus macracanthus Template:Small)
• Afrocarduus millefolius Template:Small (as Carduus millefolius Template:Small)
• Afrocarduus nyassanus Template:Small (as Carduus nyassanus Template:Small)
• Afrocarduus ruwenzoriensis Template:Small (as Carduus ruwenzoriensis Template:Small)
• Afrocarduus schimperi Template:Small (as Carduus schimperi Template:Small)
• Afrocarduus silvarum Template:Small (as Carduus silvarum Template:Small)

External links

• Template:Commons category-inline
• 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.