Common Knapweed
Centaurea nigra
Tap image to enlarge · Wikimedia Commons
Overview
Common Knapweed is one of the most important summer wildflowers for insects — its purple-red thistle-like flowers attract an extraordinary diversity of bees, butterflies, hoverflies and beetles. Dark Green Fritillary, Painted Lady and Red Admiral all visit it. On the dune grassland it grows tall and robust, flowering from June to September. The flower head has distinctive black-fringed bracts — giving it the local names 'black knapweed' or 'hardhead'.
At a Glance
| Order | Asterales |
| Family | Asteraceae |
| Habitat | Fixed dune grassland · Rough grassland · Scrub edge · Roadside |
| UK population | Very common throughout Britain on grassland and roadside |
| Sefton Coast | Common on fixed dune grassland and rough ground throughout the Sefton Coast |
| Conservation | UK Green List |
Where to See It
Fixed dune grassland, scrub edges and rough ground throughout the Sefton Coast.
Identification
Upright plant to 90cm. Dark green, slightly hairy leaves. Dark purple-red flower heads on globular base with distinctively black-fringed bracts. Looks like a thistle but leaves not spiny. Often grows with Field Scabious.
Viewing & Photography Tips
Watch Knapweed in any dune grassland in August. It's covered in insects — a good plant for beginners to start learning bee and hoverfly identification.
Conservation Status
UK Green List
This species has a favourable conservation status in the UK and remains an important part of Sefton Coast biodiversity.
Frequently Asked Questions
Why is Common Knapweed so good for insects?
Knapweed provides abundant, accessible nectar through a long flowering period (June–September). The tubular florets are short enough for both short-tongued bees and long-tongued bumblebees to access. The plant also provides seed for Goldfinches and other finches in autumn. Research consistently places Knapweed among the top five UK wildflowers for total insect visits — making it one of the most valuable wildflowers in any grassland restoration.
Related Species
Plan your visit to the Sefton Coast
Marshside RSPB, Formby pinewoods, Ainsdale NNR — practical guides to getting there, what to bring, and the best spots for each season.