Meadow Knapweed
The meadow knapweed is an invasive, noxious weed that causes damage to Colorado's ecosystem.
About This Species
The Meadow Knapweed in not native to Colorado. It is classified as a "List A" species in the Colorado Noxious Weed Act, designating it for statewide eradication. It is a fertile hybrid resulting from crossbreeding black knapweed (C. nigra) and brown knapweed (C. jacea).
Photos courtesy of Minnesota Department of Agriculture
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Physical Characteristics
Meadow knapweed is a perennial forb that grows 2-4 feet tall. The pink to purple-red flowers emerge mid-summer through fall and are 1 inch wide. The bracts are papery, fringed, and light to dark brown. Meadow knapweed has many branches ending with a single flower. The basal leaves are blue-green, up to 4 inches long, slender, with a petiole (leaf stalk). The leaves grow up to 6 inches long and more than 1 inch wide.
They may be smooth, toothed, or lobed. The stem leaves usually don't have a petiole and are much smaller, and more linear. The root of meadow knapweed is large and woody.
Habitat
Meadow knapweed prefers moist roadsides, sand/gravel bars and river banks, irrigated pastures, ditches, moist meadows, and forest openings.