Noun
A large genus of composite plants, related to the thistles and including the cornflower or bluebottle (Centaurea Cyanus) and the star thistle (C. Calcitrapa).
Source: Webster's dictionaryAdditional species that have been recognized more recently as aggressive and requiring control are yellow star thistle (Centaurea solstitialis), sweet clover ( Melilot spp. Source: Internet
Maerz and Paul A Dictionary of Color New York:1930 McGraw-Hill page 194 Further origins of the color name can be traced back to a dye produced from the cornflower (Centaurea cyanus). Source: Internet