Centaurea cyanus is an annual flowering plant in the family Asteraceae, commonly known as cornflower or bachelor’s button. Native to Europe and historically associated with grain fields, it has spread widely through cultivation and naturalization in temperate regions. The genus name Centaurea derives from the Greek mythological figure Chiron the centaur, who was said to have used related plants medicinally, while the species epithet cyanus comes from Greek kyanos, meaning “dark blue,” referring to the plant’s characteristic vivid blue ray florets. The English name “cornflower” reflects its traditional presence as a field weed among cereal crops (“corn” in older British usage meaning grain).

Centaurea cyanus produces striking blue composite flower heads composed of sterile outer ray florets and fertile inner disc florets. Historically, the plant was valued as a dye source and as a minor medicinal herb in European folk traditions, where infusions were used for mild astringent and anti-inflammatory purposes, particularly for eye washes. In modern contexts it is cultivated primarily as an ornamental and for edible flower use. Centaurea cyanus flowers are used decoratively in salads, herbal teas, and confectionery, contributing color rather than strong flavor.

Cornflower petals contain anthocyanin pigments, including cyanidin derivatives responsible for the blue coloration, as well as flavonoids such as apigenin derivatives and phenolic acids with antioxidant properties. These compounds have demonstrated free radical–scavenging activity in vitro. The flowers are generally regarded as safe for culinary use in small quantities, though like many Asteraceae species, they may provoke allergic reactions in sensitive individuals.