Common Knapweed
Centaurea nigra
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Hardhead — a thistle-like flower with no prickles at all, and the best nectar on the verge.
An upright, tough-stemmed perennial with narrow leaves and solitary red-purple thistle-like flower heads set on a hard, blackish-brown, closely scaled base — the hardhead of its country name. Unlike a true thistle it has no spines anywhere. Common knapweed is abundant on verges, meadows, railway banks and rough grassland around Dumfries.
Behaviour
Knapweed is one of the most productive nectar plants in British grassland, consistently rated at the top for the sugar it supplies, and it is worked constantly by bumblebees, butterflies, burnet moths and hoverflies through high summer. The seedheads are then taken by goldfinches and linnets in autumn. It is a mainstay of meadow restoration seed mixes for exactly these reasons.
When to see it
Quick facts
- Family
- Daisies (Asteraceae)
- Height
- 30–90 cm
- Status
- Native; abundant, and a top-ranked nectar plant
Photo by Julie Anne Workman, CC BY-SA 3.0, via Wikimedia Commons