Why Are Leaves Green? Where do Green Plants Get Their Energy From?

In summers and monsoons, the plants are full of life, and the world appears lush green. The green colour is a symbol of nature, and everyone uses green to underline their ecological spirit. But why are leaves green and not black, white or even purple? Let’s find out.

We all love the sunny shore and the tall mountains, where everything grows and blooms, where trees, shrubs, and grasses breathe in the abundant sunlight. From the entire rainbow spectrum of the colours which the light of the sun is composed of and which only appears white to us, the plants choose green. But why are leaves green?

The plants only use part of the light. They mainly take up red and blue light. In the inimitable act of photosynthesis, trees convert light into chemical energy to produce sugar and starch. On the other hand, they scorn the green light. The leaves mostly reflect or throw back the green light, and that is why leaves are green. 

Why are Leaves Green – Explanation

Leaves are green because they have a green dye in them. It’s called chlorophyll. The word comes from Greek and means green leaf. Plants need chlorophyll to grow. The green dye is the main component responsible for photosynthesis. Plants also need sunlight to grow.

It serves as an energy source for the complex chemical process of photosynthesis, in which the water from the earth and the carbon dioxide from the air are converted into high-energy carbon compounds. The carbon compounds are the basic material for the whole plant body, from which roots, stems, leaves and flowers are made.

The green leaf pigment of the plants, chlorophyll, processes the red and blue sun rays very efficiently. But why do the leaves estimate the yellow and green light as low and throw them back, when the maximum solar radiation exists in the greenish-yellow wavelength?

More radiation would certainly be there in the greenish-yellow wavelength, but the plants do not need more light to grow than the leaf green can capture. On the contrary, trees protect themselves from too much light so that their cells are not destroyed in the long run.

That’s how a tree lives.

Leaves absorb the sunlight and produce Glucose. Glucose is high in energy and is transported as fuel to all parts of the tree. The Glucose is needed to build up storage materials such as starch and sugar as well as building materials from which wood, bark and leaves are formed.

They use the leaves like solar cells, which they stretch into the light to generate energy. However, they do not generate electricity but chemical energy.

Trees need a lot of leaves to absorb energy and to survive. Although the tree sucks in air through bark and branches, the leaves are the tree’s lungs. Animals and humans benefit from these processes in the leaves of the trees since this also releases oxygen and animals need oxygen to breathe.

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How Much Oxygen Does a Tree Produce?

In a 100-year-old beech tree, 1.7 kilograms of oxygen per hour emerges from the stomata of the leaves. That’s as much oxygen as 50 people need to breathe for an hour. Because of oxygen production, photosynthesis is also the most important biological process on earth.

Trees Rest in Winter

Now we know why leaves are green, but there are seasons when the leaves are not green.

The reason behind that is the tree takes a break in the autumn and over the cold, low-water months and sheds its leaves. It regresses and slowly breaks down. The leaves lose their lush green colour and become yellow. Only in spring, when the tree boosts its metabolism again, will the dye be formed again.

But how is it that some plants don’t have green leaves at all, but red ones, such as the beech trees or some ornamental plants?

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In reality, these plants are also green. The green is only covered by other dyes called anthocyanins. These red pigments in some plants protect against excessive UV light, similar to how people get brown skin. The green chlorophylls are also hidden under this red dress and collect the energy of the sunlight.

Why leaves are green is a question of common knowledge, but there is a bigger message for all of us if we don’t understand the importance of trees.

Trees also form the basis of human life, because the energy that we consume through food is created by a plant from sunlight at the beginning of the food chain. If plants and trees don’t exist, the rest of the pyramid will fall, and humans who are at the top of the food chain will fall the hardest.

Plant a tree, save a tree.