Blue is the favorite color of more people in the world than any other, and the "blue flower" is considered a symbol of romantic longing. In nature, however, there are only a few plant species whose flowers contain blue color pigments. An international research team led by Bayreuth ecologist Prof. Dr. Anke Jentsch has investigated the reasons for this. One important factor is the great chemical effort required to produce blue dyes, however differing color perception of pollinators also plays a role. For bees, all the shades of blue assume a more conspicuous share in the colourfulness of flowers than they do for the human eye. The study was published in Frontiers in Plant Science.