Stamens emerging in the wild cornflower, Centaurea cyanus. This flower head is in fact made up of many lilac-coloured flowers, seen here protected by green bracts. Petals around the edges are from large sterile flowers. Stamens in the centre are from fertile flowers. Centaurea cyanus is of eastern Mediterranean origin and has lived closely associated with human agriculture since the neolithic era. It is now found worldwide among cereal crops, but is gradually disappearing through the use of agricultural herbicides. Leonardo da Vinci once remarked upon the very pure colour of its petals.