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Black Knapweed (Centaurea nigra) |
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Centaurea nigrescens The black appearance of the flower bases and the narrow upper leaves will almost always separate Black Knapweed from other species of the genus. Tyrol Knapweed can be mistaken for Black Knapweed. However the dark, fringed tips of the bracts do not completely conceal the pale base of the bract giving the flower head a paler appearance. Tyrol Knapweed always has a series of false rays. False rays occur in only one form of Black Knapweed. Black Knapweed (Centaurea nigra) Alien: Native of Europe. Identification: Base of flower round to ovate with an apical spray of rose to lavender florets. In one form an outer ring of florets are enlarged and appear to be a series of "rays". Bracts of flower base with apical third dark brown to black with a large outer row of elongate spines giving flower base a black appearance. Upper leaves elongate, lanceolate, without marginal teeth. Lower leaves with a more irregular outer margin, commonly with larger teeth at base of leaf. Plant 1 to 3 feet in height. Distribution: Southern Canada southward to Ohio, Maryland, and Delaware. Also occurs in the Pacific Northwest. Habitat: Black Knapweed is a weed of disturbed areas including fields, roadsides, and empty lots. Flowering period: July to September. |
Black Knapweed (Centaurea nigra)
Similar Species: Tyrol Knapweed (Centaurea nigrescens)
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Similar Species |
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