TL;DR : Plants reflect green light and absorb blue and red light from sunlight to make energy, but they can also be of different colors.
This question is the kind of matter you wondered about as a child. Growing up you may have learned all about this at school in biology class and as an adult you may have forgotten the answer to this simple, yet very very complex question. (It’s ok, we get it, we’ve all been there).
Eventually you may have just neglected to keep asking everyday questions like what does nutmeg grow on, what part of a plant is it or what is a cashew nut? (In case you are now curious, you might like the answer : respectively https://en.wikipedia.org/wiki/Myristica_fragrans and https://en.wikipedia.org/wiki/Cashew. Yep, maybe you didn’t know about cashew apples yet, pretty awesome right?)
So, let’s not get sidetracked, why are plants green? This item is one of the most important elements about plants and we understand that you want to learn more about what makes plants green – that is, chlorophyll (mostly)!
What is chlorophyll?
Chlorophyll is a compound that is known as a chelate. A chelate consists of a central metal ion bonded to a large organic molecule, composed of carbon, hydrogen, and other elements such as oxygen and nitrogen (known as chelating agents). If you’ve done a bit of chemistry or if you remember your chemistry classes from High School or College then all these terms might mean something to you if you look at the diagram a little lower. You can see the center core made of the metal ion (Magnesium – Mg) and the surrounding elements : carbon (C), hydrogen (H), and other elements such as oxygen (O) and nitrogen (N).
What does cholorophyll look like?
Chlorophyll has magnesium as its central metal ion, and the large organic molecule to which it bonds is known as a porphyrin. The porphyrin contains four nitrogen atoms bonded to the magnesium ion in a square planar arrangement. Chlorophyll occurs in a variety of forms.
The image above shows the structure of chlorophyll A.
Bonus fact : No chlorine in chlorophyll
Here is another interesting fact: Chlorophyll does not contain chlorine as the name might suggest; the chloro- portion of its name stems from the Ancient Greek word chloros, which means yellowish green. And as a bonus you’d probably also like to know that the element Chlorine derives its name from the same word. Why? Well because it is a yellowish-green gas.
You know that horrible smelling gas that stings your nose like bleach that is used in making plastics, solvents for dry cleaning and metal degreasing, textiles, agrochemicals and pharmaceuticals, insecticides, dyestuffs, household cleaning products and a bunch of other things. You may think of it when you think of going to a public swimming pool for example.). Read on in Wikipedia for more about chlorine : https://en.wikipedia.org/wiki/Chlorine. By the way, the “phyll” part refers to where it is found, i.e. in leaves (from the greek phyllo = leaf).
Why is it useful?
Leaves contain this pigment called chlorophyll. And it’s this chelate that colors the leaves green. Chlorophyll helps the plants make from carbon dioxide, water, nutrients, and energy from sunlight. This process is called photosynthesis.
So remember plants need as much light and warmth as they can get in order to feed themselves properly. If you expect to succeed at growing tropical plants in cooler climates you better get a lot of light, even in winter. After all tropical plants get a great deal of sunlight all year long in the regions where they are usually found. If you cannot provide a greenhouse or sunlight windows then you should resort to artificial lightning (for citrus trees in winter) or try some neat tricks in order to amplify and cheat with the little light you get. Sometimes you can make do with just a little.
So now we know what makes plants green, but if you want to know why plants ARE green, you should keep on reading.
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