Black Knapweed

Black Knapweed

Centaurea nigra L.

Asteraceae (Sunflower Family)

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Centaurea nigra L., Black Knapweed: (Bayer Code: CENNI; US Code CENI2)

• Simple perennial plant with stout rootstock native to Europe and found escaped from cultivation in northeastern and northwestern U.S.
• Leaves are usually oval, with pointed tips and occasionally with shallow teeth or lobes, but usually with smooth margins, and leaves are pubescent
• Stems are generally unbranched, and head inflorescences are at the tip of these stems
• Heads have pinkish-purple ray flowers of equal length, and bracts tipped with dark section that has comb-like spines along its edge, and this section of the bract bends slightly outward from the head
• Not a problem yet in Missouri
• Similar Brown Knapweed (Centaurea jacea) has brown, papery edges to the bracts underneath the head inflorescence
• Similar Greater Knapweed (Centaurea scabiosa) has pinnately-lobed leaves and tiny, dark teeth along most of the margin of the inflorescence head bracts, rather than confined to a top section as in black knapweed

(Posted January 23, 2019)

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