The Cornflower ( Centaurea cyanus ) also called Bachelor 's button , Basket flower , and Boutonniere flower is a small flowering plant in the family Asteraceae . Centaurea cyanus ( Cornflower , Bachelor 's button , Bluebottle , Boutonniere flower , Hurtsickle , Cyani flower ) is a small annual flowering plant in the family Asteraceae , native to Europe .