Chris Gomersall / Painted lady butterfly (Vanessa cardui) on Greater knapweed (Centaurea scabiosa) Norfolk, July, UK

Philippe Clement / Greater knapweed (Centaurea scabiosa) in flower near the Matterhorn, Swiss Alps, Valais, Switzerland, July 2009

Kim Taylor / Marbled white butterflies (Melanargia galathea) visiting Greater knapweed (Centaurea scabiosa) Dorset, England, digital composite

Kim Taylor / Marbled white butterfly (Melanargia galathea) visiting Greater knapweed (Centaurea scabiosa) Dorset, England, digital composite

Niall Benvie / MYN / Greater knapweed {Centaurea scabiosa} Scotland, UK

Simon Colmer / Greater Knapweed (Centaurea scabiosa) Sussex Downs AONB, Sussex UK

Simon Colmer / Greater Knapweed (Centaurea scabiosa) Sussex Downs AONB, Sussex UK

David Kjaer / Greater knapweed {Centaurea scabiosa} in flower, Wiltshire, UK.

Tony Evans / Greater knapweed {Centaurea scabiosa} in verge beside stubble field. England

David Kjaer / Greater knapweed, Field scabious, Wild carrot and Hawkbit flowering in meadow, UK

David Kjaer / Greater knapweed, Field scabious, Wild carrot and Hawkbit flowering in meadow, UK

Pascal Tordeux / Greater Knapweed (Centaurea scabiosa). Picardy, France, July.