For color variety, depending on yard location, I have a variation of Loropetalum, one Lilac, and a Japanese Maple. Had a pair of plum trees but the ornamental variety you can buy tends to not last as long.
For low ground stuff Nandina can offer greens, reds, and yellows, in good variety.
Interestingly, when organisms retain this kind of diversity it is because of the evolutionary advantage that it confers. In this case that would be the ability of plants in general to evolve towards other colors. For this to be an advantage the driver for that would have to be present in our long term environment. Possibly some sort of moderator appears in the atmosphere? Or does the spectra of the sun change due to some process?
They do. The paper's point is that plants want to choose two wavelengths with different amounts of average power. This gives the plant a window to tune within to get the desired amount of output power. If the total illumination drops, the plant compensates by tuning more towards the high power wavelength, and vice versa.
But the paper makes the point that the tuning mechanism isn't perfect due to internal noise. If the power level difference between the two input wavelengths is too great, then the random fluctuation of the tuning mechanism will itself create a lot of noise in the output. So basically there's an optimal value for the difference of average power between the two wavelengths.
Now, why the plant doesn't absorb the peak green wavelength and the closest wavelength whose power is exactly the optimal difference less was unclear to me. I think the idea was that the plant also wants to minimize the wavelength difference, and a given power delta can be achieved with less difference in wavelength in the steeper sloping sections of spectrum power graph.
I think the point is that since the power available at these wavelengths vary sharply with frequency in these regions of the solar spectrum, the plant can easily compensate for brightness fluctuations in these portions of the spectrum with minor tweaks to the target wavelength of the relevant photosystems
> It might be highly efficient to specialize in collecting just the peak energy in green light, but that would be detrimental for plants because, when the sunlight flickered, the noise from the input signal would fluctuate too wildly for the complex to regulate the energy flow.
> Instead, for a safe, steady energy output, the pigments of the photosystem had to be very finely tuned in a certain way. The pigments needed to absorb light at similar wavelengths to reduce the internal noise. But they also needed to absorb light at different rates to buffer against the external noise caused by swings in light intensity. The best light for the pigments to absorb, then, was in the steepest parts of the intensity curve for the solar spectrum — the red and blue parts of the spectrum.
I admit there's a bit of a jump there (gotta read the actual article, not the journalist retelling I suppose), but I assume the gist of the math is something like this:
Lets say direct green light delivers a maximum 100 "units of photo-energy" -- gonna play loose with the physics to demonstrate the math.
When a cloud passes over it, lets say the intensity drops to only 75%. Lets also say for now we always convert the energy at 100% efficiency.
So with green light, your 100 units of energy drops by 25 units with each passing cloud.
Now lets say blue light delivers only 80 units of energy. When that same cloud passes over, 80 * 75% = 60 units of energy, or a drop of 20 units.
So, if your process is sensitive to changes in absolute energy, you would rather have a swing of 20 units for every passing cloud than a swing of 25 units. Yeah, you might get less absolute energy (60 units rather than 75), but if the cost of energy swings in your process was very high, the tradeoff might be worth it.
You could also play with the efficiency-of-conversion (ie have higher conversion efficiency at the lower-swing points) for some fun second-order effects.
This is just a toy example of what the underlying dynamics could be. Gotta read the actual paper to understand the actual model they developed. https://arxiv.org/pdf/1912.12281.pdf
The color of plants and the statistics of light is fascinating.
Tangentially related, I was developing a CV app for farmers in an early stage weed startup right before legalization in California so they could monitor analytics on the health of their sprouts as well as identify strains. The camera conditions were all over the place and data preprocessing stage was an absolute nightmare. We tried everything from filters to background removal, augmentation techniques through transformations, noise induction for generalization - nothing really improved the baseline models because the photos honestly sucked. Farmers ignored our guidelines on lighting and framing and format and kept sending in inconsistent garbage.
I had a eureka moment. What if we sent each of the farmers a little piece of square cardboard painted magenta? The idea was that the increase in contrast would allow us to process the leaf contour a little bit better. The fact that the card was square meant some farmers even took the time to take the plant indoors so they could frame it better within the edges. Data quality improved dramatically. It worked.
Unfortunately legalization did not work out as we planned, farmers disappeared and the market was monopolized by corporations, there wasn't any interest in helping develop strains locally.
My understanding of the evolution of Earth flora is that prior to plants being green, the dominant plant life was red (think of red algae blooms) and that the current dominant green plant life likely evolved to use different photons along the EM spectrum where there was less competition.
Funny enough as I understand visible light and the EMR spectrum there is no "green" (color/wave length/energy) rather the color green is a construct originating not in the light spectrum but in the mind of the observer.
There is a range of wavelengths of light that humans perceive as green. The same is true for every color that is part of the rainbow. In contrast, the "pure purples" do not appear in the rainbow, and there is no single wavelength of light that humans perceive as purple (it requires red light plus blue light).
I had heard of the similar Purple Earth Hypothesis[1] wherein organisms with photosynthesis based on retinal arose in the oceans early on. Chlorophyll-based life developed deeper and took advantage of the red and blue light that filtered through.
The hypothesis seems pretty speculative, but maybe it's compatible with this new research, which could explain why green plants came to dominate despite retinal being simpler.
Land plants are newer than algae, but green algae is older than red algae (as evidenced by the endosymbiosis order). But maybe green algae got dominated by the others pretty early on.
edit actually that's brown algae that's the derived one. red and green it looks like both come from the original endosymbiosis.
I was thinking about the same hypothesis but IIRC it was highly speculative, with the main evidence for it simply being that modern plants evolved to use those other photosynthesizers' castoffs. We may not need that hypothesis anymore if we have a solid reason to avoid green anyway.
Second the noise difference from 10% of the green would be negligible compared to the energy we are talking about. Also how does a plant regulate this 'noise'? The only logical explanation would be expand into the green in dark and out of it in light, but they have shown no mechanism for a plant to do that.
Sorry to say that after that fairly long winded article i have come to the conclusion we still don't know exactly why plants aren't all black.
Edit; Thinking about this more, maybe Chlorophyll a and Chlorophyll b take inverted wavelengths of light to produce a rectification effect..? Its interesting, but even if that were true, it would not explain the gap at green.
2nd Edit; I stand corrected, considerably more green light make it through the atmosphere thank you for the information spacemark.
>First, green does not have the most energy of the visual spectrum, Blue, or more specific Violet does
The article is correct. Blue photons have more energy, you're right. But more green photons are emitted by the sun, and even more reach the ground through the atmosphere than blue, so the total energy from green photons is significantly greater. Google blackbody spectrum.
One theory is that yellow-green wavelengths don't pass through water as readily, hence ancestral sea-dwelling plants adapted to absorb red and blue wavelengths and that adaptation remains "good enough" for contemporary land plants.
Highly recommend the book "How the Earth Turned Green"
I might just use this trick of nature to inform how I manage my staff at work. We spend so much time trying to maximize efficiently, but perhaps at the cost of stability.
The sun is actually green (that is, is approximated by a black body emitter with a peak in the green region of the visual spectrum, see [1]). Its light appears white because that is how we are conditioned evolutionarily. ("True" white -- i.e. equal spectral energy -- appears blue-grey to us.)
The sun "looks" orange because when you can look at it (sunrise/sunset), its light is heavily filtered by the atmosphere.
Your green receptors overlap with red, and also a little with blue. There is no single wavelength of light that only stimulates your green photoreceptors without also setting off red or blue ones. https://en.wikipedia.org/wiki/Color#/media/File:Cones_SMJ2_E...
Orange is red and green. The intensity we perceive is also not the absolute intensity of that part of the spectrum. Neither is the luminosity equivalent to the power (as in energy over time).
I thought plants are green because sun is green. Edit: not sure about down votes, sun has peak in green spectrum. Our eyes are most sensitive to green, plants are green to utilize it as well.
[+] [-] raxxorrax|5 years ago|reply
https://www.ornamental-trees.co.uk/images/cercis-canadensis-...
Of course those also have chlorophyll, but the color is overridden by other color particles.
Sadly we have no blue trees. We have blue flowers though and it would probably be possible to create one. That would be so awesome.
[+] [-] MarkSweep|5 years ago|reply
https://en.m.wikipedia.org/wiki/Blue_spruce
[+] [-] tipoftheiceberg|5 years ago|reply
We do not know of any “true blue” plant pigments. There are violets and many colors that might look close..
[+] [-] Shivetya|5 years ago|reply
For low ground stuff Nandina can offer greens, reds, and yellows, in good variety.
[+] [-] sgt101|5 years ago|reply
[+] [-] mutatio|5 years ago|reply
[+] [-] russfink|5 years ago|reply
[+] [-] FriedPickles|5 years ago|reply
But the paper makes the point that the tuning mechanism isn't perfect due to internal noise. If the power level difference between the two input wavelengths is too great, then the random fluctuation of the tuning mechanism will itself create a lot of noise in the output. So basically there's an optimal value for the difference of average power between the two wavelengths.
Now, why the plant doesn't absorb the peak green wavelength and the closest wavelength whose power is exactly the optimal difference less was unclear to me. I think the idea was that the plant also wants to minimize the wavelength difference, and a given power delta can be achieved with less difference in wavelength in the steeper sloping sections of spectrum power graph.
[+] [-] uj8efdkjfdshf|5 years ago|reply
[+] [-] floatrock|5 years ago|reply
> Instead, for a safe, steady energy output, the pigments of the photosystem had to be very finely tuned in a certain way. The pigments needed to absorb light at similar wavelengths to reduce the internal noise. But they also needed to absorb light at different rates to buffer against the external noise caused by swings in light intensity. The best light for the pigments to absorb, then, was in the steepest parts of the intensity curve for the solar spectrum — the red and blue parts of the spectrum.
I admit there's a bit of a jump there (gotta read the actual article, not the journalist retelling I suppose), but I assume the gist of the math is something like this:
Lets say direct green light delivers a maximum 100 "units of photo-energy" -- gonna play loose with the physics to demonstrate the math.
When a cloud passes over it, lets say the intensity drops to only 75%. Lets also say for now we always convert the energy at 100% efficiency.
So with green light, your 100 units of energy drops by 25 units with each passing cloud.
Now lets say blue light delivers only 80 units of energy. When that same cloud passes over, 80 * 75% = 60 units of energy, or a drop of 20 units.
So, if your process is sensitive to changes in absolute energy, you would rather have a swing of 20 units for every passing cloud than a swing of 25 units. Yeah, you might get less absolute energy (60 units rather than 75), but if the cost of energy swings in your process was very high, the tradeoff might be worth it.
You could also play with the efficiency-of-conversion (ie have higher conversion efficiency at the lower-swing points) for some fun second-order effects.
This is just a toy example of what the underlying dynamics could be. Gotta read the actual paper to understand the actual model they developed. https://arxiv.org/pdf/1912.12281.pdf
[+] [-] _5659|5 years ago|reply
Tangentially related, I was developing a CV app for farmers in an early stage weed startup right before legalization in California so they could monitor analytics on the health of their sprouts as well as identify strains. The camera conditions were all over the place and data preprocessing stage was an absolute nightmare. We tried everything from filters to background removal, augmentation techniques through transformations, noise induction for generalization - nothing really improved the baseline models because the photos honestly sucked. Farmers ignored our guidelines on lighting and framing and format and kept sending in inconsistent garbage.
I had a eureka moment. What if we sent each of the farmers a little piece of square cardboard painted magenta? The idea was that the increase in contrast would allow us to process the leaf contour a little bit better. The fact that the card was square meant some farmers even took the time to take the plant indoors so they could frame it better within the edges. Data quality improved dramatically. It worked.
Unfortunately legalization did not work out as we planned, farmers disappeared and the market was monopolized by corporations, there wasn't any interest in helping develop strains locally.
[+] [-] rkwasny|5 years ago|reply
https://www.youtube.com/watch?v=N1pIYI5JQLE
[+] [-] throwaway_USD|5 years ago|reply
Funny enough as I understand visible light and the EMR spectrum there is no "green" (color/wave length/energy) rather the color green is a construct originating not in the light spectrum but in the mind of the observer.
[+] [-] Zaak|5 years ago|reply
[+] [-] VerDeTerre|5 years ago|reply
The hypothesis seems pretty speculative, but maybe it's compatible with this new research, which could explain why green plants came to dominate despite retinal being simpler.
[1] https://en.wikipedia.org/wiki/Purple_Earth_hypothesis
[+] [-] thescriptkiddie|5 years ago|reply
[0] http://www.biotele.com/magenta.html
[1] https://en.wikipedia.org/wiki/Light#/media/File:EM_spectrum....
[+] [-] unknown|5 years ago|reply
[deleted]
[+] [-] sergeykish|5 years ago|reply
* green in rainbow and prism makes it equal to other rainbow colors
* green in RGB requires pure color for wider gamut
* birds receptors are not screwed [1]
[1] https://upload.wikimedia.org/wikipedia/commons/e/e8/BirdVisu...
[+] [-] Ericson2314|5 years ago|reply
edit actually that's brown algae that's the derived one. red and green it looks like both come from the original endosymbiosis.
[+] [-] andrewflnr|5 years ago|reply
[+] [-] cortic|5 years ago|reply
First, green does not have the most energy of the visual spectrum, Blue, or more specific Violet does; https://socratic.org/questions/5348556b02bf347bedff8fed
Second the noise difference from 10% of the green would be negligible compared to the energy we are talking about. Also how does a plant regulate this 'noise'? The only logical explanation would be expand into the green in dark and out of it in light, but they have shown no mechanism for a plant to do that.
Sorry to say that after that fairly long winded article i have come to the conclusion we still don't know exactly why plants aren't all black.
Edit; Thinking about this more, maybe Chlorophyll a and Chlorophyll b take inverted wavelengths of light to produce a rectification effect..? Its interesting, but even if that were true, it would not explain the gap at green.
2nd Edit; I stand corrected, considerably more green light make it through the atmosphere thank you for the information spacemark.
[+] [-] spacemark|5 years ago|reply
The article is correct. Blue photons have more energy, you're right. But more green photons are emitted by the sun, and even more reach the ground through the atmosphere than blue, so the total energy from green photons is significantly greater. Google blackbody spectrum.
https://en.wikipedia.org/wiki/File:Wiens_law.svg
https://lh3.googleusercontent.com/proxy/eDhfILMl70XZ-WUchpgo...
[+] [-] alanbernstein|5 years ago|reply
[+] [-] unknown|5 years ago|reply
[deleted]
[+] [-] acdanger|5 years ago|reply
Highly recommend the book "How the Earth Turned Green"
https://press.uchicago.edu/ucp/books/book/chicago/H/bo164656...
[+] [-] omaranto|5 years ago|reply
https://science.sciencemag.org/content/368/6498/1490
Did you conclude "we still don't know exactly why plants aren't all black" after reading the paper?
[+] [-] stpedgwdgfhgdd|5 years ago|reply
[+] [-] hawktheslayer|5 years ago|reply
[+] [-] deeweebee|5 years ago|reply
[+] [-] Chris2048|5 years ago|reply
[+] [-] zadkey|5 years ago|reply
[+] [-] jonplackett|5 years ago|reply
The sky is blue, the sun is orangey.
Where's all this green light I'm missing?
[+] [-] colanderman|5 years ago|reply
The sun "looks" orange because when you can look at it (sunrise/sunset), its light is heavily filtered by the atmosphere.
[1] https://qph.fs.quoracdn.net/main-qimg-f9bc312e4d114e9e32a627...
[+] [-] sp332|5 years ago|reply
[+] [-] alanbernstein|5 years ago|reply
[+] [-] projektfu|5 years ago|reply
[+] [-] SeriousM|5 years ago|reply
[+] [-] kanobo|5 years ago|reply
[+] [-] 42droids|5 years ago|reply
[+] [-] OrangeKnucles|5 years ago|reply
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[+] [-] dvh|5 years ago|reply
[+] [-] laszlokorte|5 years ago|reply