African fruit 'brightest' thing in nature but does not use pigment to create its extraordinary col, page 1


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Topic started on 11-9-2012 @ 07:19 AM by elevenaugust
This odd fruit have really extraordinary iridescent colours that are not the result of pigmentation.
Indeed, Pollia condensata fruit, does not get its blue colour from pigment but instead uses structural colour – a method of reflecting light of particular wavelengths.



In the forests of central Africa, there’s a plant that looks like it’s growing its own Christmas decorations. Shiny baubles sprout from between its leaves, shimmering in a vibrant metallic blue. Look closer, and other colours emerge – pinpricks of red, orange, green and violet. It looks as if Seurat, or some other pointillist painter, had turned their hand to sculpture.

But these spheres, of course, are no man-made creations. They’re fruit. They are the shiniest fruits in the world. Actually, they are the shiniest living materials in the world, full-stop.



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 color is caused by Bragg reflection of helicoidally stacked cellulose microfibrils that form multilayers in the cell walls of the epicarp. The bright blue coloration of this fruit is more intense than that of any previously described biological material.

Uniquely in nature, the reflected color differs from cell to cell, as the layer thicknesses in the multilayer stack vary, giving the fruit a striking pixelated or pointillist appearance. Because the multilayers form with both helicoidicities, optical characterization reveals that the reflected light from every epidermal cell is polarized circularly either to the left or to the right, a feature that has never previously been observed in a single tissue.


Sources:
- Phys.org
- Pnas.org
- Nature.com
- Discovermagazine.com


reply posted on 11-9-2012 @ 08:04 AM by Pokoia
reply to post by elevenaugust


The same goes for birds like crows.
To us they look black and all the same.
To the crows they look each different.
It is done in the same way, without pigments in the feathers, and crows can see a bit more in the UV range


reply posted on 11-9-2012 @ 08:21 AM by RockHarder
reply to post by elevenaugust




Indeed, Pollia condensata fruit, does not get its blue colour from pigment but instead uses structural colour – a method of reflecting light of particular wavelengths.


Even with pigment, colors are always particular reflected wavelengths of light.

A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption.


en.wikipedia.org...

edit on 11-9-2012 by RockHarder because: (no reason given)



reply posted on 11-9-2012 @ 09:58 AM by elevenaugust
Originally posted by reficul
looks pretty cool! can you eat it???

That's a good question and here's the answer from discovermagazine.com:

Why does Pollia have such bright fruit? Here’s a clue: you can’t eat them. Well, you can eat them, but there would be no point, because they provide next to no nourishment. They’re practically a dry seed-filled husk. Here’s another clue: Pollia grows in the same regions as another plant, Psychotria peduncularis, which also produces blue berries.

The team thinks that Pollia is mimicking the tasty blue fruits of its neighbour, tempting birds with the promise of tasty pulp, but rewarding them with nothing but seeds to carry. Alternatively, birds could collect the fruits to decorate their nests, or to use in mating displays. Either way, Pollia gets a free ride, and avoids having to spend energy on making sweet, nourishing tissues. It’s an evolutionary triumph of style over substance.


Although using animals for dispersal is a strategy common to many plants, most are forced to devote precious calories to produce a sweet, fleshy pulp. This one, however, is able to spread its seeds simply by showing its true iridescent colors.


reply posted on 11-9-2012 @ 10:45 AM by reficul
reply to post by elevenaugust


ha! sounds like my ex wife!!!!
nice to look at,but no substance!!!


reply posted on 11-9-2012 @ 11:22 AM by AfterInfinity
reply to post by elevenaugust


This is the kind of nature we're destroying in favor of a steel jungle, forgetting that true beauty isn't forced.

Thank you for sharing this.
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