Colour in nature

How nature dresses to impress

Colour in nature Pollia fruit has iridescent blue and UV colour from rings laid down by cell walls.

Introduction

Colours in nature are omnipresent and serve an essential role in providing a wide range of signals:  “I am fertile!”, “I am tasty!”, “I am dangerous”.

Nanostructures in plants produce special structural colours that attract and guide animals. While the existence of structural colours in animals is well known, in plants they were thought to be rare. Now scientists have discovered that plants as well as animals dress themselves in such structural colours, and are exploring what they signal to pollinators and how to mimic them in the lab.  In this exhibit you will see plant nanostructures, learn how these produce colours and see how they appear to insects.

How does it work?

Summer Science Exhibition Opal made from self-assembly of polymer nanospheres shows structural colour changed by deformation.

Colours arise either from the selective absorption of light by pigments, or through the interference of light with transparent periodic structures on the nanometre length scale. The latter, termed “structural colours”, are typically more brilliant and optically striking.

While most colours in nature are based on pigments, which absorb part of the light, particularly vivid colours arise from transparent materials with periodic structures on the 1/1000 mm length scale.  The rainbow colours observed on CDs are a familiar example of surface structure producing colour.  Now scientists are discovering how extremely small nanostructures, invisible to our eyes, are producing similar striking colours for plants.  Intricate structures are tuned to produce UV colours, invisible to us but clear signals to insects which play the important role of pollinator. For further information please see this exhibit's website.

Video

This video demonstrates some of the science of this exhibit.