Why Are Plants Green Instead of Black?

Nothing says "nature" like a lush green forest. But why are plants green in the first place?
Hosted by: Stefan Chin
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[@meetaverma8372]

The idea of plant rejecting the light sun emits the most of sounds like they're dieting

[@dutchik5107]

Not necessarily Do you eat all the food you see?

[@TheSassi14]

They kind of are. They are on a strict blue and red light diet. No green light allowed

[@limiv5272]

@@dutchik5107 Umm that's kind of personal

[@RamdomView]

For many photosynthetics, especially marine ones, carbon dioxide or other nutrient availability is the key limiter of growth. Therefore, light is in relative excess.

[@limiv5272]

@@RamdomView I think it's things like nitrogen that are limiting. I can't imagine CO2 being limiting for the last tens of millions of years

[@Ceilingcat9001]

Me "Because the chlorophyll," 5 seconds in the video - "but why is the chlorophyll green?" This legit broke me

[@WormholeJim]

That's the power of that kind of question, every kid knows this instictively. If you notice, Stefan doesn't actually answer it either. He deftly skips it in favor of explaining what the plant uses the green colour for.

[@crediblesalamander8056]

@@WormholeJim Yup, instead of answering why chlorophyll is green, he talks about why plants aren't not green. Both are interesting.

[@WormholeJim]

@@crediblesalamander8056 Yes, yes. Yes. It's the magic of math, indeed it is. By looking at the plant you can deduce something in it must be green.

[@roychan588]

@@crediblesalamander8056 that's just a part of science. It is much easier to prove a theory wrong than prove it right. So the theory that hasn't been proved wrong yet is the most right

[@loki-of-asgard7877]

I can answer that question kind of. First you have to ask how does the human eye see color? Light sends signals to the brain through your eyes. Now chlorophyll absorbs all colors except green. Any color that isn't absorbed bounces off and reflects back to you. Here is the trippy part. That means chlorophyll isn't actually green. That is just the one color in the light spectrum that isn't absorbed by it, so you are kinda still left with the question what is it's real color? Nobody knows because the only way to see the real color of anything would be to filter out the light, but if light is how the eye sees?? Are you seeing why that is so hard to figure out. This applies to anything you see. You are not seeing it's real color, but the color of the light not absorbed and reflected off of it's surface. It gets even more nuanced when you are talking about the colors of other stuff. Things that appear white are actually not absorbing any light, so it reflects all the colors at once which appears white to us. And to it's opposite, things that are black absorb all the colors which make it appear black to the eye because no colors are left to bounce off of it. An apple appears red because it can't absorb that particular color etc In other words, we can only explain how we perceive color.

[@GRBtutorials]

Interesting... maybe this could be used to predict the color of plants in exoplanets with different star types?

[@blade97]

I'm assuming you mean in reference to the sun it orbits. Seems probable.

[@andredpg]

The exoplanet's atmosphere might have some influence as well, but your idea looks like a good one

[@calveras86]

Assuming plants exist in other planet

[@TheAgamemnon911]

@@andredpg It might filter some small bands out, but rayleigh scattering is universal.

[@jamesmnguyen]

@@calveras86 Some form of life that gains energy from the star will exist on an exoplanet.

[@andredpg]

The one question still unanswered: why is Hank Green?

[@voiceofreason9258]

Perhaps it was the mishap with gamma radiation that spawned Muscle Hank. :-)

[@crunchyoats1862]

This reaction also created Skinny Hank as a byproduct

[@Mystic_Robot]

Phenomenal question there Andre

[@calebpeterson3117]

People always ask why is hank green but never how is hank green

[@lyric939]

"some plants are purple" I'm looking at you, my calathea ornata

[@jw2223]

Yeah the theory doesn't super hold up lol... there's tons of colored plants

[@gavart4509]

Me: “well I mean I don’t really kno-“ 5th graders: “CHLOROPHYLL, ITS GOTTA BE CHLOROPHYLL- ITS CHLOROPHYLL RIGHT? BRO ITS BECAUSE OF THE CHLOROPHYLL”

[@TheSassi14]

Not all 5th graders are know it alls. Plus many adults react a similar way, just with less shouting

[@stlkngyomom]

JP Spears(with bandana on;):Well, you see,it's because of the chlorophyll we gots beer,weed and ayahuasca,so it's not like he/she's wrong.And oxygen,allegedly,but if you've gots those three,do you really need oxygen on a flat/hollow globe? You be the judge(Paul Harrel).

[@yumri4]

the part about absorbing light is more interesting than just knowing that the chlophyll is what absorbs it

[@Sergedfabre]

when I was in 5th I'm pretty only me and my nerd friends knew what chlorophyl was

[@xXxROFLOFxXx]

Now i wanna know more about these purple bacteria.

[@Kavriel]

There's purple plants too.

[@trishapellis]

@@Kavriel PBS Eons has a video on them (kinda). It's called 'when the Earth was purple'.

[@lakrids-pibe]

I never meant to cause you any sorrow I never meant to cause you any pain I only wanted to one time to see you laughing I only wanted to see you Laughing in the purple rain

[@kingnarothept6917]

@@Kavriel And red plants, since I see many around my town :)

[@themechanicalentry]

Plants that are purple, or red, or any other color, are that way due to some sort of pigment, usually to attract insects or protect itself from burns or the cold, rather than create energy. We have red algae and purple algae that use different pigments for the photosynthesis, though.

[@lyndsaybrown8471]

Omg, you can't just ask why someone's green.

[@koopametalpack]

This title is anti namek

[@krieg1583]

Is anti hank

[@alveolate]

@@koopametalpack but pro mr popo

[@SaltpeterTaffy]

green light bad reee

[@exosproudmamabear558]

Its racist

[@harku123]

I was LITERALLY just asking this question in my head about an hour ago

[@jw2223]

There are plants with black foliage... and red foliage... and purple foliage... think about the purple lettuce in your salad.

[@talideon]

Of course, this is a radical simplification, because there are a whole bunch of plants that have purple leaves, or stems, thus attuning them partially or wholly for absorbtion of green light. This episode deserved a follow-up.

[@Helveteshit]

@SciShow, in recent years due the growing popularity of Grow Lights. There is a hint of studies that show that plants may be Green because it allows it to pass through green rays to foliage that are shaded beneath, which may be other branches of a tree or the plant. Making it appear, as if the green colour is also a way of them to provide nutrients to leaves in the shade of the top growth.

[@QuestionEverythingButWHY]

“The mind is not a vessel to be filled, but a fire to be kindled.” ― Plutarch

[@GhostBusters815]

Its crazy how nature has figured out how to handle a lot of different situations it makes sense how it could take millions of years to perfect

[@3nertia]

It's a numbers game

[@HmmmmmLemmeThinkNo]

I really love that you don't need to watch the video itself, bc I use these videos to keepe occupied during my scheduled look outside time (to keep my eyes healthy I have to look outside for so long so many times a day)

[@uss_04]

Plants: I reject your emission spectrum and substitute my own

[@neuralnetwork17]

I've been asking myself this question for years, but I could never figure it out. Thank you, SciShow.

[@Ahlivianne]

It is always so exciting to hear your university's name in these videos. Good job UCR!

[@dans4323]

I've also heard that plants do absorb a small part of green (and reflect most). Apparently red/blue is mostly absorbed in the upper 5% of the leaf and the green light that is absorbed can penetrate deeper.

[@realdragon]

Makes sense, there are no materials that can reflect 100% of light

[@kimbratton9620]

One of my favorite channels!!

[@Scribe13013]

That's not a shirt he's wearing...it's actually a tattoo

[@Zaihanisme]

Scribe13 🤭

[@ESL-O.G.]

Getting tired of his shirt.

[@tpope2044]

Why do certain types of trees, like the Japanese Maple, have purple leaves?

[@blade97]

Are they an under canopy tree( a tree that grows best in shade)?

[@tpope2044]

@@blade97 I've always seen them planted out in the sun. I don't know what their natural environment is like, but there's more than one species like that, I just don't know the names.

[@DANGJOS]

@@tpope2044 Anthocyanins are the pigments, and they absorb UV light, so it's likely a sunscreen. I'm sure there are other reasons for it, but I'm no expert.

[@CrownofMischief]

Same thing with cherry plums

[@kingnarothept6917]

@@DANGJOS Either that or for whatever reason, they might have a high melanin content in them.

[@conlon4332]

I saw this and thought "Huh. Very good question." and my mum was just confused.

[@LinkFreak9999]

I've been asking this specific question for weeks now. Thanks for making this video.

[@theoverseer393]

This sounds very helpful for power grids, should they become more efficient

[@exosproudmamabear558]

Power grids do not cook or sweat or die when there are no sun so probably not.

[@KKayTheFirst]

Black plants? I would've loved that as an emo teen

[@CDM10000]

The darth vader begonia is pretty black

[@NajwaLaylah]

Black mold: "Am I a joke to you?"

[@gearandalthefirst7027]

there's some plum trees by my house that black/very dark purple

[@OsedayCan]

There's lollo rosso, aquilegia, black pennisetum, black heuchera, black bamboo, sambucus nigra and many other nearly completely black plants.

[@sdfkjgh]

@@OsedayCan: "Yer mother was a hamster, and your father smelt of _S. nigra!"_ --Some scientifically-minded French person, probably.

[@toastghost9145]

Excellent timing; I was wondering this just the other day.

[@QuestionEverythingButWHY]

"Be less curious about people and more curious about ideas." -- Marie Curie

[@SoftSemtex]

i love yall, but there are so many jumps in this... first theres the HUGE assumption that the absorption spectrum of chlorophyll is subject to selective pressure: it's not a gene product and therefore cant change incrementally through mutations with incrementally different absorption spectrums . then the minor issue of surges in absorption, which is a thing that plants actually counter with different proteins that define C3, C4 and CAM photosynthesis, way easier than inventing a new pigment. lastly the purple bacteria: calling it a "color" makes it sound like it's the same as plants with purple leave, which are the combination of different pigments, instead of a different process alltogether. i am SO sure there is a scishow video about how ancestors of purple bacteria ruled the oceans untill the meekly chloroplasts, who had to subsists on the leftover light, formed an unholy alliance with early plant cells, poisoning everyone with their oxygen waste and therefore claiming dominion over this earf?

[@SoftSemtex]

also: when i search for "why green", top result is "why is my poop green?" - by scishow

[@jenerix5257]

I remember that video too. I was wondering if this new theory means they don't think that happened anymore.

[@HasekuraIsuna]

Yeah, I was sitting here too remembering them explaining this completely differently just some months ago!

[@HidaAtarasi]

I’ve often wondered wether solar panels would be more efficient were they green, rather than black.

[@allymessner2954]

Hi

[@realdragon]

No they wouldn't. If they were green it would mean they reflect some wavelengths instead absorbing them and turning into energy, plants are alive and need to care about things like not killing their cells while we are able to build solar panels that can withstand higher temperatures

[@legacyoflore1597]

I've wondered about this so often!

[@al2642]

Whaaaaaat! The purple prediction is just amazing!!!

[@hiei82]

I have wondered about this exact question for years! Thank you!

[@artifactland69]

Wow a video that's about something I really did learn in middle school (not completely, but partially)

[@kaminari1028]

Some leaves do have a purplish tiny. I’m not a botanist, but they typically look more tropical. It makes sense.

[@jacobegaca409]

Nice “it’s not easy being green” reference

[@QueenetBowie]

Could you do a video on why some ocean water is clear, like in the Caribbean, and some is grey like the beaches in New York?

[@цветок-ш7п]

on other planets, plants are black. I'm gonna be an astrobiologist.

[@Ewr42]

Good luck, cocaine

[@andresacosta5318]

Astrobotnist

[@silver_kitten]

Many

[@цветок-ш7п]

@@Ewr42 thank you :)

[@Nosirrbro]

Shakhter Siren' I was really wondering if someone was gonna mention that

[@CMZneu]

great video!

[@ohiojosh78]

This would be great info for Sci-fi and video games

[@crunchyoats1862]

I want that T-shirt

[@landravac]

That being green joke killed me

[@PlantYes]

This is superinteresting! Definitely will discuss this with my students :)

[@fally2000]

UC Riverside! It's great to see your school represented!

[@Shenron557]

3:48 very interesting... I have a plant at home (purple-heart) which has purple leaves. It prefers to grow in shaded conditions.

[@yurikha]

i read the title and it seemed familiar, didnt you cover this already?

[@annanananan1261]

Thank you!! I've always wondered this

[@dans4323]

Another theory (although less popular) is that in the earth's early life halobacteria dominated the sea and they absorb green (and are therefore purple). So only red and blue light was available below them and early algae had to make due with that so chlorophyll prospered below.

[@amitoj]

Can we get a video on force mechanics of bicycle and how to optimize your gears and pedal lengths

[@Laaiiv]

I hear that a lot lately that plants don't absorb green light, and we talked about it with a professor. He said it's not completly true, the just absorb a little less green light than those of other wave lenghts, but still quite a bit of it.

[@ts7015]

This is the question I asked in my secondary school and I was seen as a FOOL. EVERYBODY in my class laughed at me.

[@chuckpuckett7288]

But chlorophyll isn't the only pigment plants use. You become aware of that in October if you live in the Northern Hemisphere. Almost all of those pigments are red, yellow, or orange, so they are absorbing greens, blues, and violet (high energy) light. These pigments are always there, I use a lab in my biology class to show that.

[@dyingofcringe8839]

black plant be like: CHLOROPHYLL, I REJECT MY GREEN!

[@lucky-segfault]

Neat! have you considered an episode on how laser diodes work and why they can only emit certain colors of light

[@alexreifschneider6709]

Could it have to do with the availability of magnesium in early plant development?

[@BilledMySpeer]

Dear Mr. SciShow. Please make a video explaining where there is continental crust and oceanic crust. I understand that there is a density difference, but why is there a difference.

[@edwardtbabinski]

Magnesium is the central atom in the chlorophyll molecule. Chlorophyll is the pigment that gives plants their green color and carries out the process of photosynthesis.

[@jangreygarin3107]

Why some plants have unique characteristic like holes and splits in their leaves and why some of them change differently from juvenile vs adult form one?

[@Slacquerr]

Makes me wonder if there were primordial populations of plants that were not green but died out.

[@brandonkelley6500]

I wish a video like this came out in 2016. For Biology 1 in college I had to explain why I chose a wavelength to measure growth of chlorella in a spectrophotometer. So I was searching to why plants were green. Unfortunately I became overburdened by the one of the worlds most stupid circular arguments: "Plants are green because they reflect green light. Plants reflect green light because they are green." I ultimately found an article saying the sun's strongest energy output was green light. So I ultimately assumed that since it was the strongest wavelength, it would have been too much energy for the plant. It wasn't until a year or two ago last earth day multiple science channels released videos putting forth their reasoning that was better than that stupid circular argument.

[@MinnaMe01]

Was a bit surprised this episode wasn’t hosted by Hank, would’ve felt fitting somehow😜

[@lasarousi]

I initially thought that green is the opposite of the energy frequency that the plant actually absorb efficiently.

[@Dichtsau]

u could've aswell made an episode "why is the banana not straight"

[@Mrl5247gg]

I always had this question

[@O1sson]

What gasses are inside of a bell pepper or paprika

[@brescalofrio1]

Wow.

[@paulex12]

Just normal atmospheric gasses. Maybe a little depleted of CO2 and a bit more water vapor. Plant tissues are full of air spaces that are continuous throughout the plant and connect to the outside of the plant through stomata and lenticels.

[@omegamanrad]

Wow plants are very “green” about energy 😉

[@melne6101]

•_•

[@DrywallJackson]

this was such a bad joke that i demand a written apology

[@PixieStixx]

YAY for Dad Jokes! 😃

[@primrose6794]

@@DrywallJackson I demand a full apology video.

[@VR_Wizard]

3:13 Why differences in wavelengths lead to a changing power output by the cloroplast and why do similar wavelengths dampen each other? I would not expect interference as the reason for this. Has it something todo with the photosystem 1 and 2 and how they absorb light?

[@FastFunFactFriday]

This causes more questions, like why is infrared from sunlight so hot when measured if green is the most abundant?

[@gaylemilln9456]

I guess that's why some plants start turning red when they get a lot of sun.

[@simonsaysism]

wow, I was thinking about this just one or two days ago and trying to google up an answer. spooky

[@arthurkropf794]

I just found out why my Weed Grow on the forest floor went wild with colours! xD

[@BCElginTex]

It would be interesting to see the results of the simulations using different colors of light like maybe that emitted by a red dwarf star on a a nearby orbiting large rocky planet with say 70%ish of its surface covered in water. I'd like to see what colors those plants might be.

[@realdragon]

I wonder if they would be black, green is the peak of Sun's spectrum and red giants or white dwarfs might have peak outside of visible spectrum. So maybe in that case plants would try to absorb whole visible spectrum because it's not as intense

[@tonyug113]

Isnt there some connection in that the initial pre-dominant organism was blue/green algea that and chlorophyl based organaisms kind of scrapped a living on the margins, until tyhe blue/green algea kind of poisoned themselves with their own by-product (oxygen), chlorophyl organisms then took over (presumably oxygen tolerant), but were left with their basic built in machinery, presumably too big a step and kind of unnecessary to change.

[@thecreepysunbabyfromthetel4657]

Maybe they just felt like it, y’know?

[@цветок-ш7п]

lol your comment, pfp and username are hilarious

[@thecreepysunbabyfromthetel4657]

@@цветок-ш7п Lmao thanks. :,)

[@oldrabbit8290]

but what about grass and plant in arid/steppe/savanna? should the lack of canopy above them, as well as cloud cover, mean a more stable input of sunlight for them? would they need green leaves in those situations? also, the world used to be covered by purple bacterias, which absorb green light for photosynthesizing, until our green ancestor just gas them with oxygen. So it seems that other colors (like purple) were doing quite well for themselves. In fact, I have seen some edu channels (like MinuteEarth) put out a theory that, because these purple bacterias had hogged all the green light for themselves, our ancestor bacterias, which lived deeper, had to make do with other lightwaves - and that trait simply carried on down the line.

[@Bruhhfsfs]

I don't understand how rejecting some of the light spectrum is balancing out fluctuations. 1. If something covers a plant it doesn't matter if it is absorbing a part of the light spectrum or all of it, the plant is still loosing near 100% of its power source . 2. Also, if a plant absorbed all sunlight it would have more to compensate a sudden drop in say, red light. 3. Being able to compensate for a drop in a specific part of the light spectrum only makes sense to me when the plant is used to absorbing 2 parts of the light spectrum, and then being able to change which parts of the light spectrum it absorbs based on the type of light coming in. This means a plant would change colour. Please tell me how I'm wrong here. I think I'm missing something with waves, idk I still don't understand why they reject green. But I would love to know.

[@jacobcoolguy]

So pink light is the best 💖

[@lv6506]

Question: What is the temperature range of photosynthesis; and how will global warming affect plant survival and food production?

[@Tourarounwarsaw]

The Almighty Gods incredible creativity.

[@nathanlamberth7631]

Hmmm so now I’m going to assume if a plant has dark leaves (but is otherwise normal) it’ll be a shade lover

[@chriseaton1525]

What part of the chloroplast is doing the reflection? Is it the chlorophyll it self or wrapper as part of its structure?

[@Mirandorl]

There actually are quite a few black plants, for example some dahlia types have beautiful black stems and leaves.

[@maninderbabra]

Hank Green can shed more light on this

[@nitzeart]

So what about plants that have leaves with other colors, like red/purplish, or with pink splotches?

[@TheNighthawke502]

Maybe it's just me, but I wonder if this knowledge can be applied to human issues like our archaic electrical power grids as well as improved designs for solar panels, both of which can experience the same or similar fluctuations. Food for thought at least....

[@ThePCguy17]

Not an electrician, but couldn't you solve the problem of irregular input with a capacitor of some kind? Something to pick up the slack in low-input times and absorb the excess in high-input times?

[@jollyjokress3852]

I kind of don't get this fluctuation thing. Why does leaving out the medium-energy wavelength reduce fluctuation amplitudes?? Anyone knows?

[@JosePineda-cy6om]

Purple Earth. That theory explains it best, it's way simpler, and more consistent with the fossil record: plants evolved to absorb blue/red, and avoid absorbing green, because halobacteria evolved first and they absorbed groen light. Sadly, the type of photosynthesis halobacteria do (based on retinol) doesn't generate oxygen as a by-product, s opposed to chlorophyl-based one, which means the ancestors of plants killed 80% of all life back then thru the great oxygenation, whereas halobacteria now live in marginal environments

[@matheusdias4463]

um salve pra quem veio pelo umberto

[@studiant3004]

É nóis ＼(ﾟｰﾟ＼)

[@aarononeal9830]

Yall need to do a video about ecosia they are a search engine that plants trees

[@ElGroggy]

I hear, in deep sea, some photosynthesis seaweeds were red.

[@100tjl]

Bugleweed, purple blackish, when you mow it down to grass levels

[@canaan5337]

My thought is that the reason plants are green is because they need to reject most of the light emitted by the sun because photosynthesis doesn't require that much light, and any extra light that they absorb that they don't use for photosynthesis just raises the temperature of the plant's leaves which would cook and kill the leaves then the plant wouldn't be able to photosynthesize at all and it would die.

[@MastuhP]

why do flowers have different colours

[@MusicalBotany]

This has absolutely overwhelmed my little botany-addicted brain with glee. Plants are so amazing!

[@lucidality]

Or perhaps it could be used the other way around too. If we know the color of a prehistoric plant maybe it could be used to measure what the climate was around that time period

[@anthonyau6925]

I agreed that plants need "a balanced wavelength", just like we need "a balanced diet".

[@istvansipos9940]

and now: With green leaves so practical, why are some plants NOT green? what do they gain? thanx

[@ykshay]

THERE ARE FULLY PURPLE TREES AAAAAA

[@B00s3]

Joe Hanson on 'Its Okay To Be Smart' has done a great video on this (I believe PhysicsGirl did too), he (and she) explains this very well. Info in this video seems to be a bit different ... either I'm remembering wrong or this is new info on the subject or all the above or I'm just going insane.

[@mvsawyer]

One thing that evolution teaches us is that given billions of years, trial and error will come up with some fascinating solutions to complex problems.