SafePlants

Brown Knapweed (Centaurea jacea)

Brown Knapweed, also known as Brown-rayed Knapweed, Common Knapweed, or Hardheads, is the subject of this article. It's a perennial herb belonging to the Aster family.

Considerations for Pets

• The plant has bare, spherical flower buds with deeply toothed brown to blackish components.
• It is thistle-like in appearance.

Taxonomy and Nomenclature

• Scientific Name: Centaurea jacea L.
• Family: Asteraceae (Aster family)
• Common Names: Brown Knapweed, Brown-rayed Knapweed, Brown -ray Knapweed, Brownray Knapweed, Common Knapweed, Hardheads.
• Synonyms: The text indicates "Aka common knapweed, hardheads, brown-ray knapweed" as alternative names.

Distribution and Habitat

• Native to Europe and introduced to North America.
• Requires fairly cool, moist locations.

Ecological Role

• Considered noxious in some areas.

Morphological Characteristics

• Clump-forming, herbaceous perennial.
• Lance-shaped, shallowly-lobed, grey-green leaves.
• Flowerheads are an aggregation of small individual flowers, containing both ray and disk flowers.
• Consists entirely of disc florets, plus long ray-like flowers on the outer edge.
• Bracts at the base of each flower head are covered with dark brown or black fringed margins.
• Flower heads are made up of 40 to 100 purple (or rarely white) ray flowers.
• Stems are 1-few, erect or ascending, openly.

Interactions with Other Organisms

• Attracts Marmelade Hoverflies.
• Flowerheads with long rays attract butterflies including meadow brown, wall, large white and gatekeeper.