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.[2]
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 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.
