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.
A waxy coating is a strong selector for survival in an environment where preventing evaporation is a must, such as locations in which the ambient temperature drops below the freezing point of water for much of the year.
Color is what we perceive, nothing else. If it looks blue, it is blue.
I might be wrong, I'm no botanist.
We do not know of any “true blue” plant pigments. There are violets and many colors that might look close..
You're referring to pigment; there is no blue plant pigment, true, but that seems a little pedantic, even if it's interesting. Plenty of flowers reflect blue light, which is what people mean when they say an object is "blue".
We have a way to describe objects which “generate a blue color when light shines on them”. We say they are “blue” objects.
Likewise, bird feathers or butterfly wings which absorb/reflect light based on their small-scale structure and appear blue are still called “blue”, even though they might be colorless when pulverized.
There are plenty of “blue flowers” out there.
Interestingly, the one dye listed in the link above that came from a plant is indigo, which is extracted from the green leaves of the plant https://en.wikipedia.org/wiki/Indigofera_tinctoria . There's no animal or plant I know of that both appears blue and could be used to create even a poor blue pigment, though I'd definitely be interested in any exceptions I haven't heard of.
* https://www.jstage.jst.go.jp/article/fishsci1994/61/6/61_6_9... -- see figure 2 on page 4, showing extracted carotenoproteins
Microstructure interference can create blue, but perhaps not the flower pigments themselves
> For plants, blue is achieved by mixing naturally occurring pigments, very much as an artist would mix colours. The most commonly used are the red pigments, called anthocyanins, and whose appearance can be changed by varying acidity.
It's just saying the same thing, "a red pigment appearing blue", without any explanation. (Also, as artists know, blue and red are primary colors, you can't get blue by mixing red paints.)
For low ground stuff Nandina can offer greens, reds, and yellows, in good variety.
Having said that, "Green = provides a convenient way for animals to identify a great source of energy" is likely to be one driver here.
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.
It makes sense the changing environmental conditions for a molecule could affect the wavelengths of light it absorbs (for example, pH, temperature, etc), but I'm not sure this has been demonstrated for plant pigments?
> 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
That's not exactly it. The idea is that the blue light absorption can be tuned (presumably by shifting the absorbed wavelengths by a few nanometer) to compensate for external changes. So if the overall light intensity drops 1%, the system responds by shifting the absorbed spectrum to get 1% more power.
This only works in parts of the solar spectrum where power varies sufficiently versus wavelength, hence the preference for blue and red.
The paper doesn't really try to explain the biological tuning mechanism. Instead, they created a model of an antenna network capable of tuning. As in, this model had a bunch of parameters describing how it captured light and tuned. Then if they optimized those parameters for stability given the light spectra that different plants are exposed to, they found that their model would reproduce the actual absorption spectra of those plants. This strongly suggest that the plants have done the same optimization by evolution.
I wonder if anyone has used RGB LEDs and tormented plants with short cycle color changes yet? There's much anecdata and debate over spectrum vs efficiency in indoor gardening, but it's faded as power density became more obviously dominant, i think.
But the slopes in the red and blue sections allow you to adjust the input power significantly by tweaking slightly the wavelength of the incoming light.
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.
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.
Fun fact, the color blue does not appear at all in the Iliad, Homer describes the ocean as wine, despite the stunning blue colors of grecian seas.
Purple is a chord.
What is curious is how color words evolve. Most languages have between two and eight basic color words (and color concepts). Those with two colors is almost always the same two colors- light and dark. The third color is usually red-brown. And fourth usually blue-green.
People literally can see the difference between blue and green even if their language doesn't differentiate between the two, I don't know if you're misremembering a claim and a negation sneaked in so please don't take this post too harshly if that's the case, but the idea that say Japanese people can't tell the difference between blue and green is patently false and should be addressed, in fact the video you linked almost does so at 2:34 -
>Some researchers took this and other ancient writings to wrongly speculate that earlier societies were colour blind.
That Homer described the ocean as wine in colour is not an issue of perception but one of language in trying to describe a colour that is not differentiated from other colours, the same is true for other 'perception' issues in the ancient world like green coloured honey. To be clear visual acuity tests have been done on modern populations and tribes which don't differentiate between such colours or overall define less colour categories and it should be no surprise to learn that they can see the difference between those colours just fine.
The whole idea that it's a difference in perception is fraught with issues, like what happens when a language naturally develops words for new categories of colours or new colours? Does a generation undergo the collective experience of literally being able to see/differentiate a new colour? If so why isn't this written about more, is it something that only happens in kids? What would be the reason for this sudden shift in perspective, because it certainly isn't a physiological change that occurs.
What happens when an adult learns a second language which differentiates between more colours? The classic romanticised view here is that learning a new language literally let's you see the world in a different perspective, but then why is it that enhanced perspective rarely more than a curiosity (language x has two words for this colour)? The Russian language has separate words for a dark blue (siniy) and a light blue (goluboy) but English doesn't differentiate between them, do the Russians see an extra colour? What does the science say? Well the science is somewhat interesting here, Russians are able to differentiate between dark blues and lighter blues ever so slightly faster (124ms), but this is worlds apart from the claim that some languages are literally capable of seeing more colours.
In general this line of thinking is known as linguistic relativity, or the view that language shapes perception and cognition, and is something that has generally been discredited among linguists as being discriminatory and harmful as well as being based on faulty reasoning or studies and occasionally fraudulent papers. For example, and I really don't mean to attribute any malice to your post, but if we're considering Homer as being unable to differentiate between an ocean blue and a dark red wine, what do we make of cultures and languages that don't differentiate between smoking, drinking, or eating? Do they not know the difference between those actions? What about the Pirahã people who only have two words (differentiated by tone) for 'small quantity' and 'large quantity' and no other words for numerals? This line of thinking is fairly harmless when applied to the way we perceive colours but can be actively harmful to people who perceive the world the exact same way we do but don't have as expressive language for these particular topics.
For anybody interested in more linguistic oddities and/or the damage linguistic relativism can do I recommend the book 'The Language Hoax' by John McWhorter, there's also an hour long talk on it available on Youtube . The book deals with the more recent studies on how language affects the ways we think in a grounded way and shows how minor some of the best examples given can be like in the case of dark and light blue in Russian. The book is also in response to the general public's view and romanticism of linguistic relativity and in particular in response to a book by another linguist Guy Deutscher titled 'Through the Language Glass', where Guy feeds into the perception that language helps shape the way we think, and it is a good book but it still doesn't get close to saying that other languages see more colours.
* plants - trees, grasses, flowers, native and garden species, once I knew maybe 400 names, now come to disuse and quickly slip away
* food - ingredients and prepared
* fonts - Comic Sans, Times New Roman, Helvetica and many more
* car models - a lot of people know them by heart
It would be a strange claim we do not perceive difference without a name. We do but we do not care. And when we care we want to communicate and names become handy.
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.
* 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 
edit actually that's brown algae that's the derived one. red and green it looks like both come from the original endosymbiosis.
First, green does not have the most energy of the visual spectrum, Blue, or more specific Violet does;
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.
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.
Highly recommend the book "How the Earth Turned Green"
Did you conclude "we still don't know exactly why plants aren't all black" after reading the paper?
Still not sure why the absorption points couldn't be uniformly widened by nature, but i will go over the paper more thoroughly when time allows, its very interesting. thank you.
The sky is blue, the sun is orangey.
Where's all this green light I'm missing?
The sun "looks" orange because when you can look at it (sunrise/sunset), its light is heavily filtered by the atmosphere.