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knapweed

Scientific Name: Cyanopsis

Family: Asteraceae

Category: Dicot

Growth:

Duration:

Other Names:

       

Common Knapweed (Centaurea nigra)

Common Knapweed, scientifically known as Centaurea nigra, is a robust wildflower often found in grasslands and meadows. It belongs to the daisy family (Asteraceae) and is recognized for its thistle-like flower heads. Other common names include Black Knapweed and Hardheads.

Considerations for Pets

  • Some species of Knapweed have spiny leaves.

Considerations for Children

  • The plant has the nickname "Hardheads". If you pinch the flower bud, it is hard.

Taxonomy and Nomenclature

  • Scientific Name: Centaurea nigra
  • Family: Asteraceae (Daisy family)
  • Common Names: Lesser Knapweed, Common Knapweed, Black Knapweed, Hardheads
  • Synonyms: Several names are used depending on the region, including Horse Knops and Paintbrush.

Distribution and Habitat

  • Native to the UK, Centaurea nigra can be found across a wide range of habitats.
  • Common locations include grasslands, roadside verges, woodland rides, cliff tops, and lawns.

Ecological Role

  • Knapweeds, as a group, are considered invasive weeds in some regions.
  • Spotted and diffuse knapweed are considered regionally noxious.
  • Spotted knapweed is known to replace native vegetation in areas where it spreads.
  • Russian knapweed spreads much slower than spotted and diffuse knapweed.

Morphological Characteristics

  • Common Knapweed is a thistle-like plant.
  • The plant has purple flowerheads that resemble thistles.
  • Stem leaves are lanceolate, which is different from the branched linear leaves of Greater Knapweed.
  • It is a medium to tall hairy plant with erect stems that may be branched or unbranched.
  • The plant is thickened below the flowerhead.
  • Flowerheads are typically purple, measuring 20 to 40 mm, and can be solitary or in branched groups.

Interactions with Other Organisms

  • Knapweed is a favorite of pollinating insects and is particularly valuable towards the end of summer when other wildflowers have finished flowering.
  • Liked by bees and butterflies.

Quirky Facts

  • The name "Knapweed" is derived from the Anglo-Saxon word "cnaep," which means top, knob, or button, referring to the flower bud.

Further Information

  • RHS (Royal Horticultural Society)