Naked Science Forum

General Science => General Science => Topic started by: Alfred96 on 27/07/2018 14:46:34

Title: Why are plants green?
Post by: Alfred96 on 27/07/2018 14:46:34
If you clicked this to answer "Because they contain chlorophyll" I already know that. The blue/green side of the rainbow contained a lot more energy than the red/yellow side, yet plants reflect reflect this higher energy light away. Some plants are red, like the Japaneses Maple so I know it's POSSIBLE for plants to be red. I'd just like to know why most plants evolved to be green. It seems to me that reed plants would have an advantage, being able to harvest more energy from limited sunlight.
Title: Re: Why are plants green?
Post by: Kryptid on 27/07/2018 17:42:18
If you wanted to absorb as much solar energy as possible, you would go with black plants. However, one explanation that I read a while back stated that absorbing too much light would be harmful for plants because it would make them excessively hot. That may have something to do with the fact that they are a color that reflects some of the light away.
Title: Re: Why are plants green?
Post by: evan_au on 28/07/2018 09:35:40
I heard another hypothesis that green chlorophyll first appeared in aquatic plants/algae.
As I recall, the argument went something like:
- higher frequency/higher energy photons at the blue end of the spectrum get scattered away, leaving mostly red light at the bottom of the water column.
- I vaguely recall comments about some other organisms that absorb middle wavelengths, so perhaps there was little benefit for the algae to absorb these wavelengths.
So green chlorophyll is very efficient at absorbing the red end of the spectrum (and also at the blue end).
https://en.wikipedia.org/wiki/Chlorophyll#Photosynthesis
Title: Re: Why are plants green?
Post by: Kryptid on 28/07/2018 21:00:58
I heard another hypothesis that green chlorophyll first appeared in aquatic plants/algae.
As I recall, the argument went something like:
- higher frequency/higher energy photons at the blue end of the spectrum get scattered away, leaving mostly red light at the bottom of the water column.
- I vaguely recall comments about some other organisms that absorb middle wavelengths, so perhaps there was little benefit for the algae to absorb these wavelengths.
So green chlorophyll is very efficient at absorbing the red end of the spectrum (and also at the blue end).
https://en.wikipedia.org/wiki/Chlorophyll#Photosynthesis

Sounds plausible. If true, we could expect the evolution of green photosynthetic organisms on quite a few extrasolar planets around G-type stars. I guess the corresponding plant color would be different if the star was a different temperature.
Title: Re: Why are plants green?
Post by: rami999 on 08/08/2018 19:45:15
i guess they have melanin just like us