Centaurea cyanus is an annual flower native to Europe that escaped gardens and became naturalized across southern Canada and the United States. Also known as garden cornflower and blue bottle, Centaurea cyanus belongs to the Asteraceae family.
The diverse Centaurea genus includes over 350 species. The alternate leaves of this plant are different. The leaves close to the ground are usually larger than those on the upper stem.
Although the lower leaves are somewhat serrated, the upper leaves are typically lanceolate, narrow, and have entire margins. The bluish-purple (often pink to white) flowers bloom on stems 1 to 3 feet tall from late spring through summer.
Each flower (up to 1.5-inches in diameter) is surrounded by an envelope of overlapping bracts.