Cirsium

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Cirsium
Thistles-2.jpg
Cirsium vulgare (Spear Thistle)
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Asterales
Family: Asteraceae
Subfamily: Carduoideae
Tribe: Cynareae
Genus: Cirsium
Species

About 200;[1] see text

Cirsium is a genus of perennial and biennial flowering plants in the Asteraceae, one of several genera known commonly as thistles. They are more accurately known as Plume thistles. These differ from other thistle genera (Carduus, Silybum and Onopordum) in having feathered hairs to their achenes. The other genera have a pappus of simple unbranched hair.[2]

They are mostly native to Eurasia and northern Africa, with about 60[1] species from North America (although several species have been introduced outside their native ranges).

Thistles are known for their effusive flower heads, usually purple, rose or pink, also yellow or white. The radially symmetrical disk flowers are at the end of the branches. They have erect stems and prickly leaves, with a characteristic enlarged base of the flower which is commonly spiny. The leaves are alternate, and some species can be slightly hairy. Extensions from the leaf base down the stem, called wings, can be lacking (Cirsium arvense), conspicuous (Cirsium vulgare), or inconspicuous. They can spread by seed, and also by rhizomes below the surface (Cirsium arvense). The seed has tufts of tiny hair, or pappus, which can carry them far by wind.

Cirsium thistles are used as food plants by the larvae of some Lepidoptera species - see list of Lepidoptera that feed on Cirsium. The seeds are attractive to small finches such as American Goldfinch.

Most species are considered weeds. Cirsium vulgare (Bull Thistle, Common Thistle, or Spear Thistle) is listed as a noxious weed in nine US states.[3] Some species are cultivated in gardens for their aesthetic value and to attract butterflies. Some other common species are: Cirsium lanceolatum, Cirsium palustre, Cirsium oleraceum.

Certain species of Cirsium, like Cirsium monspessulanum, Cirsium pyrenaicum and Cirsium vulgare, have been traditionally used as food in rural areas of Southern Europe. Cirsium oleraceum is cultivated as a food source in Japan and India.

The word 'Cirsium' derives from the Greek word kirsos meaning 'swollen vein'. Thistles were used as a remedy against swollen veins. The flower blooms April to August.

Species[edit]

Hybrids
  • Cirsium × canalense - Canal Thistle
  • Cirsium × crassum - Thistle
  • Cirsium × erosum - Glory Thistle
  • Cirsium × iowense - Iowa Thistle
  • Cirsium × vancouverense - Vancouver Thistle

Image gallery[edit]

Cirsium arizonicum (Arizona Thistle). 
Cirsium canum (Queen Anne's Thistle). 
Bumblebee on thistle flower. 
Cirsium vulgare (Bull Thistle, Common Thistle, or Spear Thistle). 
Cirsium pyrenaicum cut and ready to cook. 
Texas Purple Thistle 

Notes[edit]

  1. ^ a b "Cirsium". Flora of North America. 
  2. ^ Rose, Francis (1981). The Wild Flower Key. Frederick Warne & Co. pp. 377–380. ISBN 0-7232-2419-6. 
  3. ^ "PLANTS Profile for Cirsium vulgare (bull thistle) USDA PLANTS". USDA Plant Database. USDA. Retrieved 2008-07-15. 

Further reading[edit]

  • Everitt, J.H.; Lonard, R.L.; Little, C.R. (2007). Weeds in South Texas and Northern Mexico. Lubbock: Texas Tech University Press.  ISBN 0-89672-614-2