Bluebonnet, a name given to several different kinds of plants with blue flowers. The plant most commonly called a bluebonnet is a small annual prairie wildflower that is the state flower of Texas. The stem, about 12 inches (30 cm) high, bears silky-haired leaves and clusters of blue flowers with yellowish-white centers. In early spring the bluebonnet carpets wide areas of the Southwest with blue. Among the other plants sometimes called bluebonnets is the bachelor's button. Bachelor's Button. )

The plant most commonly called a bluebonnet is Lupinus subcarnosus of the pea family, Leguminosae.The cornflower belongs to the family Asteraceae, also called Compositae. It is Centaurea cyanus.