CENTAUREA

genus of about 500 species of herbaceous plants of the composite family (Asteraceae). Most are native to the Old World and chiefly centred in the Mediterranean region. The genus includes a wide variety of annual and perennial garden plants such as the cornflower, or bachelor's button (C. cyanus), and the basket-flower (C. americana). Others are variously known as knapweed, thornless thistle, cardo-del-valle, dusty miller, blue bottle, mountain bluet, sweet-sultan, hard heads, and Spanish buttons.