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

Silvia Reiche / Map Butterfly (Araschnia levana) on Knapwort Harshweed (Centaurea jacea), Hoogeloon, Noord-Brabant, Netherlands

Silvia Reiche / Map Butterfly (Araschnia levana) on Knapwort Harshweed (Centaurea jacea), Hoogeloon, Noord-Brabant, Netherlands

Silvia Reiche / Map Butterfly (Araschnia levana) on Knapwort Harshweed (Centaurea jacea), Hoogeloon, Noord-Brabant, Netherlands

Wild Wonders of Europe / Widstrand / Brown knapweed (Centaurea jacea) flower, Sardinia, Italy, June 2008

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

Jouan & Rius / Bot thistle {Centaruea sp} flower and buds, Fair island, Shetland Islands, Scotland, UK

Gary K. Smith / Summer wildflower meadow with Corn marigold {Chrysanthemum segetum} and Cornflower {Centaurea cyanus} UK, July

Jose B. Ruiz / Cornflower (Centaurea cyanus) flowering in coastal pine tree forest (Pinus halepensis), Cadiz, Spain

Jose B. Ruiz / Star thistle flower {Centaurea seridis} Spain

Gary K. Smith / Cut flowers in bucket on garden seat, UK

Niall Benvie / Abstract impression of Common poppies {Papaver sp.} and Cornflowers {Centaurea sp.}, UK, June

MYN / Niall Benvie / Cornflower {Centaurea cyanus} UK meetyourneighbours.net project

Niall Benvie / Abstract impression of Common poppies {Papaver sp.} and Cornflowers {Centaurea sp.} UK, June

MYN / Niall Benvie / Cornflowers {Centaurea cyanus} UK meetyourneighbours.net project

MYN / Niall Benvie / Cornflower {Centaurea cyanus} UK meetyourneighbours.net project

MYN / Niall Benvie / Cornflower {Centaurea cyanus} UK meetyourneighbours.net project

MYN / Niall Benvie / Cornflower {Centaurea cyanus} UK meetyourneighbours.net project

MYN / Niall Benvie / Cornflower {Centaurea cyanus} UK meetyourneighbours.net project

Philippe Clement / Cornflower (Centaurea cyanus) in flower, Luxembourg

Adrian Davies / Mountain / Perennial cornflower (Centaurea montana) UK

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

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

Tim Fitzharris / Cornflower (Centaurea cyanus) and Mexican Hat (Ratibida columnifera) flowers in field, North America

Tim Fitzharris / Cornflower (Centaurea cyanus) and Pointed Phlox (Phlox cuspidata) blooming in grassy field, North America

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

David Kjaer / Lesser / Black Knapweed {Centaurea nigra} in flower, Wiltshire, UK.

Philippe Clement / Clouded yellow butterfly {Colias crocea} on flower {Centaurea sp.} La Brenne, France

Jose B. Ruiz / Rough star thistle {Centaurea aspera} in flower. Spaini

Ross Hoddinott / Crab spider (Xysticus cristatus) on Common knapweed (Centaurea nigra) with bumble bee (Bombus terrestris). Dunsdon nature reserve, Devon, UK

Solvin Zankl / Seed heads of Cornflower (Centaurea cyanus), Europe. Cornflower seeds are partly dispersed by ants and also carry a tuft of hygroscopic (water-absorbing) fibres that expand when wet and retract when d...

Solvin Zankl / Seed heads of Cornflower (Centaurea cyanus), Europe. Cornflower seeds are partly dispersed by ants and also carry a tuft of hygroscopic (water-absorbing) fibres that expand out when wet and retract wh...

Solvin Zankl / Flower of Cornflower (Centaurea cyanus) Europe

Solvin Zankl / Flower of Cornflower (Centaurea cyanus), Europe.

Niall Benvie / Cornflower {Centaurea sp.} Estonia.

Philippe Clement / Single flower knapweed {Centaurea uniflora} Gran Paradiso NP, Alps, Italy

Martin Gabriel / Cornflowers {Centaurea cyanus} flowering in barley field, Bavaria, Germany

Martin Gabriel / Cornflowers {Centaurea cyanus} flowering in barley field, Bavaria, Germany

Philippe Clement / Close up of flower of Blessed thistle {Centaurea benedictus} France

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

Ross Hoddinott / Lesser / Black knapweed {Centaurea nigra} UK

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

Philippe Clement / Mountain cornflower {Centaurea montana} Gran Paradiso NP, Alps, Italy

Philippe Clement / Single flowered knapweed {Centaurea uniflora} Gran Paradiso NP, Alps, Italy

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

Pascal Tordeux / Greater Knapweed (Centaurea scabiosa). French Alps, July.