Centaurea

Taxobox
name = "Centaurea"

"Centaurea" ("Cen-tau-ré-a") is a genus of about 350-500 species of herbaceous thistle-like flowering plants in the family Asteraceae, mostly native to the Old World. Common names for different species include star- thistle, cornflower, knapweed and bluet. Some species are cultivated as ornamental plants in gardens.

Classification

Research in the late 20th century shows that the genus, as traditionally defined, is polyphyletic. A number of 19th and 20th century efforts to reorganize the genus were not successful, and it is not yet clear what the results of the recent research will be for classification of this genus and other related genera.cite web | url = http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=106012 | work = Flora of North America | title = Centaurea]

pecies

Species in this genus include:
*"Centaurea adpressa"
*"Centaurea aggregata"
*"Centaurea akamantis"
*"Centaurea alpestris"
*"Centaurea alpina"
*"Centaurea americana" ("Plectocephalus americanus") – American Star-thistle
*"Centaurea appendicigera"- endemic in Turkey
*"Centaurea argentea"
*"Centaurea aspera" – Rough Star-thistle
*"Centaurea atropurpurea"
*"Centaurea babylonica"
*"Centaurea behen"
*"Centaurea bella"
*"Centaurea bovina"
*"Centaurea bulbosa"
*"Centaurea cachinalensis"
*"Centaurea calcitrapa" – Purple Star-thistle or Caltrop - Europe
*"Centaurea calcitrapoides"
*"Centaurea chilensis"
*"Centaurea cineraria" – Dusty Miller
*"Centaurea clementei"
*"Centaurea cyanus" – Cornflower
*"Centaurea dealbata"
*"Centaurea debeauxii"
*"Centaurea depressa"
*"Centaurea diffusa" – Diffuse Knapweed
*"Centaurea diluta"
*"Centaurea dschungarica"
*"Centaurea eriophora"
*"Centaurea floccosa"
*"Centaurea gayana"
*"Centaurea glastifolia"
*"Centaurea grinensis"
*"Centaurea gymnocarpa"
*"Centaurea horrida"
*"Centaurea hypoleuca"
*"Centaurea iberica" – A spiny Mediterranean species thought to be the "thistle" mentioned in "Genesis"
*"Centaurea imperialis"
*"Centaurea jacea"
*"Centaurea kasakorum"
*"Centaurea kopetaghensis"
*"Centaurea kotschyana"
*"Centaurea leucophylla"
*"Centaurea macrocephala"
*"Centaurea maculosa" – Spotted Knapweed; eastern Europe; introduced in North America, now an invasive weed which releases a toxin that reduces growth of forage species.
*"Centaurea mannagettae"
*"Centaurea marschalliana"
*"Centaurea melitensis"
*"Centaurea moschata" - Sweet Sultan
*"Centaurea monocephala"
*"Centaurea montana" – Perennial Cornflower
*"Centaurea nigra" – Black Knapweed or Common Knapweed
*"Centaurea nigrescens" – Tyrol Knapweed; southern and eastern Europe
*"Centaurea orientalis"
*"Centaurea ovina"
*"Centaurea paniculata"
*"Centaurea phrygia"
*"Centaurea pindicola"
*"Centaurea polypodiifolia"
*"Centaurea pulcherrima"
*"Centaurea ragusina"
*"Centaurea rothrockii" ("Plectocephalus rothrockii")cite web | url = http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=125862 | title = Plectocephalus | work = Flora of North America]
*"Centaurea ruthenica"
*"Centaurea rutifolia"
*"Centaurea sadleriana" – Pannonian Knapweed
*"Centaurea scabiosa" – Greater Knapweed
*"Centaurea seridis"
*"Centaurea sibirica"
*"Centaurea simplicicaulis"
*"Centaurea solstitialis" – Yellow Star-thistle; Europe.
*"Centaurea squarrosa"
*"Centaurea stenolepis"
*"Centaurea stoebe"
*"Centaurea sulphurea"
*"Centaurea transalpina"
*"Centaurea tchihatcheffii" - endangered species, Mogan Lake, Ankara, Turkey
*"Centaurea trichocephala"
*"Centaurea triniifolia"
*"Centaurea triumfettii"
*"Centaurea uniflora"
*"Centaurea virgata"

Nectar

"Centaurea" are copious nectar producers, especially on high-lime soils, and are major honey plants for beekeepers. Star-thistle varietal honey is light and slightly tangy. It is one of the finest honeys produced in the US; but being abundant, some of it is fraudulently relabeled and sold as the scarce, expensive Sourwood honey of the Appalachian Mountains.

The high nectar yield of the genus makes it very attractive to insects such as butterflies and day-flying moths such as Six-spot Burnet. The larvae of some other Lepidoptera species use "Centaurea" species as food plants - see list of Lepidoptera that feed on Centaurea.

References

* [http://rbg-web2.rbge.org.uk/cgi-bin/nph-readbtree.pl/feout?FAMILY_XREF=&GENUS_XREF=Centaurea&SPECIES_XREF=&TAXON_NAME_XREF=&RANK= Flora Europaea: "Centaurea"]
* [http://plants.usda.gov/java/profile?symbol=CENTA USDA Plant Profile: "Centaurea"]
* [http://www.efloras.org/florataxon.aspx?flora_id=3&taxon_id=106012 Flora of China: "Centaurea" species list]
* [http://flora.huh.harvard.edu/FloraData/060/PDF/V04/Volume4-Part2_Centaurea.pdf Flora of Chile: "Centaurea" (pdf)]
* Mabberley, D.J. 1987. "The Plant Book. A portable dictionary of the higher plants". Cambridge University Press, Cambridge. 706 p. ISBN 0-521-34060-8.
* Robbins, W.W., M. K. Bellue, and W. S. Ball. 1970. "Weeds of California". State of California, Dept. of Agriculture. 547 p.