meadow knapweed (Centaurea pratensis)
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meadow knapweed (Centaurea pratensis)
ODA rating: B
USDA Symbol: CEDE5
Oregon meadow knapweed distribution
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Images courtesy of Dan Sharratt, Oregon Department of Agriculture

If images are downloaded and used from the ODA web site please be sure to credit the photographer.
Meadow knapweed blooms in midsummer to fall. It grows from woody root crown and up to 3 1/2 feet tall. The lower leaves are long-stalked, upper leaves have no stalk. Stems are many-branched and tipped by a solitary flower head up to one inch wide. Flower heads are pink to reddish purple, oval or almost globe-shaped. A key identifying feature is the fringed bracts on the flower head. A hybrid of black and brown knapweeds. Its foliage is coarse and tough. However, because meadow knapweed is a hybrid, it traits can very.
Meadow knapweed out-competes grasses and other pasture species, causing productivity to decline. It is susceptible to herbicide treatments, but control efforts must persist for the long-term. It has the potential to invade native prairie and oak savannah.  Meadow knapweed favors moist roadsides, sand or gravel bars, river banks, irrigated pastures, moist meadows, and forest openings. It also can invade industrial sites, tree farms, and grasslands.
Native of Europe. Well distributed in the Pacific Northwest.
Distribution in Oregon

Biological controls
Some approved biological control agents released for other knapweeds have become established on meadow knapweed including a seed head fly, a seed head moth, and two seed head weevils. This plant is currently being tested as a host for other approved knapweed biocontrol agents.

meadow knapweed (Centaurea pratensis)