Centaurea jacea x nigra
Why is knapweed a problem?
Knapweeds are aggressive invaders that spread quickly through meadows and pastures, out-competing desirable forage and native plants.
Knapweeds reproduce by seed and may also regenerate from the root crown.
Knapweed produces toxins at its roots which stunt the growth of nearby plants and displaces native species.
Recommendations for controlling knapweed
Recognizing meadow knapweed
Meadow knapweed, a hybrid or other knapweed species, is a perennial that grows one to five feet tall.
Flowers are purple to white on solitary flower heads. Bracts at the base of each flower are light to dark brown with papery margins. Leaves grow up to six inches long and are one and a quarter inches wide. They are smooth or slightly lobed and decrease in size up the stem.
Meadow knapweed grows in meadows and pastures, forest openings, roadsides, waste areas and floodplains of rivers and streams.