COUNCIL CHRONICLE – According to a new study, normal flowers attract bees with a special trick ‘imbedded’ in their petals, which have a series of nanoscale ridges on their surface that generate what scientists are calling the “blue halo”.
The results of this latest research indicate that even the simplest flowers may be more complex than they seem at a first glance, as the “blue halo” is an elaborate optical illusion.
“The exciting thing is that it is a new optical trick – we didn’t know that flowers could use disorder to generate a specific color, and that is quite clever,” says the study co-author, Professor Beverley Glover.
Flowers Attract Bees Thanks to the Light, and Not Their Smell
This newest research is based on a previous study which determined that the petals of some flower species have tiny ridges on them. These were noted to be capable of diffracting light and also of bending it. In turn, this gives the flower itself a sort of iridescent sheen.
Now, a team of University of Cambridge specialists took these results one step further as they took a closer look at the tiny ridges and bumps. Using several microscopy techniques, the team examined and analyzed the petals of 12 different species of the flowering plant family tree and how these scattered and diffracted light.
This helped show that each species of flower presented a different ridge “architecture”. While some of them showed variations on the spacing of these ridges, others had fluctuating heights.
However, all the flowers were noted to have two elements in common. All of them had a weak iridescent sheen around their petals, and in all the cases, the ridges were observed to be scattering blue and ultraviolet light.
This creates an optical illusion that the team is calling a “blue halo” and which can be seen even with the naked human eye in darkly pigmented flowers, says the team.
The Blue Halo, Another Reason Why Flowers Attract Bees
To test the effects of this optical illusion, the study team created a series of “fake flowers”. One had a smooth surface, and the other had ridges that produced either a blue halo or an iridescent sheen.
Then, bees were released on them and faced with black squares with a sweet or bitter tasting solution.
Even though the squares got rearranged, the bees learned and were able to go straight to the sweet solution squares. They were also better at it when the squares had a blue halo, even more so than when they had the iridescent sheen.
Scientists believe that flowers may have adapted the petal ridges as an independent part of their evolution. This might have appeared as a way of attracting pollinators, especially as these are very good at seeing UV and blue light.
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