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Author Topic: Why are plant leaves green, not black?  (Read 6698 times)

ROBERT

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Why are plant leaves green, not black?
« on: 28/11/2005 17:22:44 »
If the leaves of plants are their "solar panels", then why are they green and not black like man-made solar panels ?, (which efficiently absorb all visible light).
[Possible clue: green leaves appear black in purple light]
This question arose from a thread in the astronomy forum,
"do green stars (suns) exist ?".
« Last Edit: 28/11/2005 17:44:30 by ROBERT »


 

Offline daveshorts

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Re: Why are plant leaves green, not black?
« Reply #1 on: 28/11/2005 23:48:12 »
There are at least 2 types of chlorphyl in plants one that absorbs red light and another that absorbs blue, leaving out green. I don't know whether there is no convinient chemical that will absorb green in the right kind of way, or whether the energetic cost of having a third form of chlorphyl would not be worth the extra light you would collect.
 

Offline Ultima

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Re: Why are plant leaves green, not black?
« Reply #2 on: 29/11/2005 08:52:20 »
You can get plants with black leaves :) well purple.
 

ROBERT

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Re: Why are plant leaves green, not black?
« Reply #3 on: 29/11/2005 10:13:13 »
Hi Ultima,
I have seen purple plants but currently the most fashionable colour for plants is green.

Hi Daveshorts,
if photosynthetic life began in a purple environment then this would explain why plants are green.
There is evidence that billions of years ago the oceans were purple:-

http://www.rsc.org/chemistryworld/News/2005/October/06100502.asp
 
Also it is possible that our sun was purple billions of years ago when photosynthetic life first appeared.

In purple light the optimum colour to absorb light is green,
green leaves would appear black (like solar panels) in purple light.

The reason plants are green is probably more complicated,
like "Daisyworld", (Gaia hypothesis).
« Last Edit: 29/11/2005 10:33:34 by ROBERT »
 

The Naked Scientists Forum

Re: Why are plant leaves green, not black?
« Reply #3 on: 29/11/2005 10:13:13 »

 

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