This section is from the book "Nature's Garden", by Neltje Blanchan. Also available from Amazon: Nature's Garden; An Aid To Knowledge Of Our Wild Flowers And Their Insect Visitors.
"If blue is the favourite colour of bees, and if bees have so much to do with the origin of flowers, how is it that there are so few blue ones? I believe the explanation to be that all blue flowers have descended from ancestors in which the flowers were green; or, to speak more precisely, in which the leaves surrounding the stamens and pistil were green; and that they have passed through stages of white or yellow, and generally red, before becoming blue." - Slr John Lubbock in "Ants, Bees, and Wasps."
Types of Leaves