The colors of flowers have inspired us for centuries. They are described through poems and songs, and have inspired iconic works of art such as Vincent Van Gogh’s Sunflowers.
But the flowers did not change their color to attract humans, but pollinators. Therefore, to understand why flowers produce such striking colors, we must consider how bees perceive color.
When viewed under a microscope, most flower petals show a textured surface made up of ridges or bumps. This research, published in the Journal of Pollination Ecology , shows that these structures have evolved to interact with light and enhance the color produced by pigments beneath the textured surface.
Sunny daze
Bees and bumblebees can perceive colors that are invisible to us, such as those produced by reflected ultraviolet radiation.
For this reason, plants must produce remarkable colors to stand out from other plant species. In fact, flowers that do this are more likely to be visited by bees and pollinate successfully.
How bees use flower surfaces
Flowering plants are known to typically have conical-shaped cell structures within their petals, and flat petal surfaces are relatively rare.
A single plant gene can control whether a flower has cone-shaped cells within the surface of a petal, but why this evolved is unclear.
Previous research suggested that the conical surface of the petal acted as a cue to attract pollinators. However, experiments with bees have shown that this is not the case.
Other explanations relate to hydrophobicity (the ability to repel water). But again, experiments have revealed that this might not be the only reason.
Therefore, the scientists decided to investigate how bees use the surfaces of flowers (with or without conical petals).
Flowers meet the needs of bees
To carry out the study, the scientists first measured the surfaces of the petals of a large number of plants and identified the most common conical surfaces.
They then selected relatively smooth surfaces and leaves that reflected light from an artificial source. Lastly, they showed it to the bees while they were flying freely.
The experiment showed that, when the light came from behind the bees, there was no preference for the type of flower. But for bees that flew towards plants that reflected light, there was a significant preference for flowers with a more irregular conical surface.
This uneven surface served to blur the incoming light, enhancing the flower’s color signal.
Thus, the researchers were able to conclude that the flowers likely developed uneven surfaces to minimize light reflections and maintain the color saturation and intensity necessary to attract pollinating insects.
