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.
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.
Species in this genus include:
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.