A large genus of composite plants, related to the thistles and including the cornflower or bluebottle (Centaurea Cyanus) and the star thistle (Centaurea Calcitrapa).

knapweed; star thistle

Centaurea (syn. Cyanus L.) is a genus of about 350-500 species of herbaceous thistles and 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.