black knapweed

Asterales > Asteraceae > Centaurea nigra L.
Synonym(s): black knapweed

Black knapweed is a perennial plant that can grow from 1-3 ft. (0.3-0.9 m) tall. Leaves, near the base, are petiolate, oblanceolate, shallowly dentate and 2-10 in. (5-25 cm) long. As leaves move up the stem, they become smaller, sessile, linear, and entire. Flowering occurs from June to October, when purple (rarely white) flowers appear in heads at the tips of the branches. Bracts that subtend the flower head are dark brown to black with numerous wiry lobes along the margins. Black knapweed is native to Europe and was first found in the United States in 1895 in Pullman, Washington. Preferred habitat includes roadsides, waste places, fields and clearings.

Identification, Biology, Control and Management Resources

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Flower(s); seedhead
Cindy Roche, ,
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Plant(s); in flower
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Invasive Reference(s):

Check for most current lists.
  • Washington - Noxious Weed Law

External Links

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USDA Forest Service Bugwood University of Georgia