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According to Wikipedia,

...plants are green because chlorophyll reflects green light. And chlorophyll is found in all plants because it is the molecule that absorbs the light that is used to make sugar.

(Wikibooks, Biology, Answering the Big Questions of Life/Photosynthesis)

I want to make life on my planet interesting, so is there any reason that plant-like organisms on an Earth-like world will evolve to reject green AND blue light (making the leaves cyan)?

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    $\begingroup$ Yes, absolutely: Cyanobacteria $\endgroup$
    – Alexander
    Nov 30, 2017 at 22:58
  • $\begingroup$ Lol, I didn't think of that. However will cyano "trees" be able to populate land areas to the point where the planet looks cyan? $\endgroup$
    – JSCoder says Reinstate Monica
    Nov 30, 2017 at 23:00
  • $\begingroup$ Make your plants don't lose phycobilin (phycocyanin) during the evolutionary process, and you will have your cyan-colored forests and pastures :) $\endgroup$
    – Alexander
    Nov 30, 2017 at 23:15
  • $\begingroup$ Yeah @sphennings, but I was impatient and selected the first answer that suited my purposes $\endgroup$
    – JSCoder says Reinstate Monica
    Dec 1, 2017 at 13:11
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    $\begingroup$ Possible duplicate of What colour would leaves be in a hydrogen-based atmosphere? $\endgroup$
    – John
    Dec 3, 2017 at 4:29

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There are different types of light-absorbing pigments even in the Earth biology. The famous world-conquering cyanobacteria is photosythesizing using bluish pigment (phycocyanin). The fact that most of the plants use chlorophyll may be simply specific to prevalent biochemistry on Earth. Under different conditions something else may be preferred during evolution

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    $\begingroup$ Why? Chrolophyl is preferred because it's more energy efficient. What would make less efficient molecule preferred? $\endgroup$
    – Mołot
    Dec 1, 2017 at 15:49
  • $\begingroup$ @Molot, Quickly: evolution is about survival of the fit, if you are good enough you pass, you survive. There are no bonus points for being extra fit. so having a less "efficient molecult" would not be a detrement unless it imposed a penelty. This is kind of like how second rate software systems can take over the marketplace. $\endgroup$
    – P Chapman
    Dec 1, 2017 at 17:21
  • $\begingroup$ @PChapman by this logic phycocyanin must've imposed penalty, because it was "evolved out". $\endgroup$
    – Mołot
    Dec 2, 2017 at 11:02
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    $\begingroup$ @Congenital-Optimist, While your answer is correct in every way. I feel tne need to clarify that phycocyanin ( en.wikipedia.org/wiki/Phycocyanin ) is an "accessory pigment" (an attenna strcuture to get extra light and send it the core chlorophyls in the light harvesting complex which are very similar between cyanobacteria and all the plants. Sorry specilaized in this, feel the need to take, I;m taking classes to fix that. $\endgroup$
    – P Chapman
    Dec 3, 2017 at 2:12
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    $\begingroup$ chlorophyll is actually less much efficient than some other photosynthetic pigments, like those in halobacteria, plants one becasue they were the first photosynthetic eukaryote. That is to say they won because of things unrelated to chlorophyll. $\endgroup$
    – John
    Dec 3, 2017 at 4:27
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As previously mentioned, evolution isn't always about the best solution, but instead can be the result of simply being the first. Even if an organism is less effective, if it can secure a large enough foothold before other organisms, then it is incredibly difficult to displace them. But I have a couple of other reasons that this might be.

  1. The atmosphere of the planet somehow filters out red and blue light, necessitating a different pigment choice.

  2. A mutation caused a plant to become unable to produce chlorophyll but simultaneously added a different trait that made it more successful thus overriding that detriment. (Many plants have secondary photosynthetic pigments, so this would not necessarily mean doom for the plant.)

  3. Your planet receives an inordinately large amount of sunlight. Chlorophyll is better in lowlight environments, but it has no distinct advantage over other pigments in extremely sunny environments.

While not specifically for cyan colored plant life if you also want red foliage you can have your plants use phycoerythrin as their photosynthetic pigment. This is the pigment that gives red algae their coloration. If you want cyan plants, then as previously mentioned phycocyanin is your ticket. You might also look into what is being done in artificial photosynthesis research, as that may lead to some novel pigments that nature simply would not have come up with.

An interesting note with plants, they can survive a much greater degree of mutation in their DNA than animals can, so having your plants mutated by something as extreme as a solar flare is not out of the question.

Hope something in this helps.

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  • $\begingroup$ Continuing with evolution not picking the best solution, you might note that chlorophyll is not very efficient at converting sunlight to biomass: around 3-6% per Wikipedia. (While photovoltaics can do 20-45%.) But that's enough to let plants survive and prosper. $\endgroup$
    – jamesqf
    Dec 3, 2017 at 4:16

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