Bachelor’s Button

Centaurea cyanus

Bachelor’s Button

Family: Asteraceae

Other Common Names: cornflower
Weed class: monitor list
Native to: parts of Asia and Europe
Is this Weed Toxic?:

not known to be

Why Is It a Noxious Weed?

This plant is on the monitor list. Please contact its sponsor Julie Sanderson to report locations or for more information.

How would I identify it?

General Description

Bachelor’s button is an annual or winter annual, covered in grayish hairs, growing to around 3-4 feet tall (1.2 meters). Flowers can vary in color from white to purple to blue.

Flower Description

Flowerheads are greater than 1 inch in diameter with bracts at the base, having lacerated, fringed margins (teeth around 1 mm). Flowers are typically blue, though can also be purple, pink, red, or white. Marginal flowers in the flowerhead have enlarged, irregular corollas, somewhat bell-shaped.

Leaf description

Leaves are narrow, generally with smooth leaf edges, though lower leaves are occasionally toothed or lobed along the margins. Leaves at the base 1.2-3.9 inches (3–10 cm) long, stem leaves usually not much smaller except among the flowerheads.

Stem description

Plants typically have one main stem that is branched toward the tip.

Fruit Seed Description

Seeds (cypselae) are straw or pale blue in color, 4-5 mm long, finely hairy with bristles attached to one end that are 2-4mm long.

Where does it grow?

Bachelor's button has naturalized over much of the United States, escaping cultivation as an ornamental and can be found in a variety of habitats including grasslands, woodlands, forests, roadsides and other disturbed sites.

How Does it Reproduce?

Bachelor's button reproduces by seed.

For More Information

Images and information from the Invasive Plant Atlas of the United States on Centaurea cyanus

WTU image database for Centaurea cyanus

Flora of North America description of Centaurea cyanus

Additional Photos