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by Allegro » Sat Sep 01, 2012 1:09 am
by justdrew » Sat Sep 01, 2012 7:09 pm
by Allegro » Sat Sep 01, 2012 10:22 pm
by Allegro » Sun Sep 02, 2012 9:29 am
by Allegro » Sun Sep 09, 2012 2:26 am
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by Allegro » Mon Sep 10, 2012 1:45 pm
by Nordic » Mon Sep 10, 2012 3:52 pm
by justdrew » Mon Sep 10, 2012 11:05 pm
African fruit 'brightest' thing in nature - but!.. does not use pigment to create its extraordinary colour
September 10, 2012
Most colours around us are the result of pigments. However, a few examples in nature – including the peacock, the scarab beetle and now the Pollia condensata fruit – use structural colour as well. Fruits are made of cells, each of which is surrounded by a cell wall containing cellulose. However, the researchers found that in the Pollia condensata fruit the cellulose is laid down in layers, forming a chiral (asymmetrical) structure that is able to interact with light and provide selective reflection of only a specific colour. As a result of this unique structure, it reflects predominately blue light.
The scientists also discovered that each individual cell generates colour independently, producing a pixelated or pointillist effect (like those in the paintings of Seurat). This colour is produced by the reflection of light of particular wavelengths from layers of cellulose in the cell wall. The thickness of the layers determines which wavelength of light is reflected. As a result, some cells have thinner layers and reflect blue; others have thicker layers and reflect green or red. The researchers believe that the plants invest in the complicated colouring structure as a mechanism for seed dispersal. Although the Pollia fruit does not provide any nutritional value, birds are attracted to its bright colouring – possibly as a means of decorating their nests or impressing their mates. Dr Beverley Glover from the University of Cambridge's Department of Plant Sciences, who jointly led the research, said: "This obscure little plant has hit on a fantastic way of making an irresistible shiny, sparkly, multi-coloured, iridescent signal to every bird in the vicinity, without wasting any of its precious photosynthetic reserves on bird food. Evolution is very smart!"
by Allegro » Wed Sep 12, 2012 1:29 am
by Nordic » Wed Sep 12, 2012 4:24 am
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