Compare with: greater knapweed

Black knapweed Centaurea nigra

Also known as: hardhead, lesser knapweed


Best time to see: mid Jul to late Sep

Key facts

A widespread perennial meadow plant with red-purple thistle flowers, growing up to 90 cm tall

Narrow pointed leaves grow singly up the stem; aka hardhead because of its firm, rounded head

An important source of nectar for many species of butterfly and bee; regarded as a noxious weed in parts of North America

  • Main photo

Photo © Tony Gunton