why are plants green?
Although the range of shades of plants is infinite, green is undoubtedly the colour par excellence of the plant kingdom. We live surrounded by greenery everywhere: in the countryside, in cities, and in the outdoor and indoor spaces of our homes and workplaces.
have you ever wondered why plants are green? The answer lies in a process millions of years old that continues today and allows plants to survive and thrive.
Elements that cause plants to be green
You will no doubt have heard of photosynthesis and chlorophyll, the latter even if only as an ingredient in chewing gum and toothpaste J. Chlorophylls are tiny photosynthetic pigments (capable of absorbing light and preparing it for photosynthesis), located in chloroplasts, from where they absorb that light. Chloroplasts are oval-shaped organelles, inside of which chlorophyll is contained, thanks to which photosynthesis can take place.
Photosynthesis
Photosynthesis is a chemical process that transforms inorganic matter into organic matter using the energy of sunlight. This process is carried out as follows: plants take up water through their roots and transport it to the leaves through the stem. On the other hand, they absorb carbon dioxide through pores in their leaves, called stomata. This triggers a chemical reaction which, thanks to the energy of sunlight, transforms the water and carbon dioxide into glucose and oxygen, allowing the plants to grow and obtain their food.
So when autumn comes and plants look different colours, is it because they have lost their chlorophyll? not at all! These tiny particles are simply hidden under other pigments, which is why, at certain times of the year with fewer hours of sunlight, the landscape is tinged with reddish and yellowish tones.
We already know that chlorophyll is what gives plants their green colour. Now, the logical question is: why does chlorophyll have this colour?
Chlorophyll
We can say that chlorophyll is the natural dye that makes plants green. It is present in many of the elements of plant organisms, and while it gives them their green hue, this is not actually its main purpose.
Let's look for a simile to understand it better: for example, polar bears. These animals have a magnificent coat of white fur on their skin. This is not just for aesthetic reasons or to show off their cool fur in the Arctic. Thanks to this colour, they are able to camouflage themselves in the snow and hunt their prey. Therefore, their colour is not an end in itself, but a means to an end, which in this case is to get food. In the case of plants, it is similar: the purpose of chlorophyll is not to colour them green to make them look pretty, but to better capture light through this colour so that they can photosynthesise and thus obtain food.
Why chlorophyll is green and how this colour helps plant photosynthesis
In this case, it is a question of energy. Light is made up of tiny particles of energy called photons. The energy of a photon is determined by the frequency of the light: the higher the frequency, the higher the energy. The frequency of blue light is higher than that of red light, so blue photons will have more energy than red photons.
Sunlight is very abundant in red light photons and to a much lesser extent in blue light photons. Chlorophyll seeks to capture both the parts of the spectrum that are most abundant and those with the highest energy, so it uses an intermediate spectrum of light: green. In this way they seek to optimise the uptake of the forms of light from the sun.
why did green aquatic plants conquer the earth?
Finally, we only need to know how the plant world managed to reign on the earth's surface. Simple. As Darwin proved: evolution and adaptation! Plant life originated in the sea, from where, over the centuries, they would emerge and conquer the earth's surface through a long and slow process of adaptation.
Under the sea there were a multitude of photosynthetic organisms whose pigmentation was different from that of other species because they were better at capturing the ranges of light penetrating the water. The difference in shades was influenced by factors such as the degree of filtration of light from the atmosphere or from the water, or the different depths reached by the water. Their greater or lesser impact on the underwater species caused the differences in colour between them.
But why was it the green algae and not the yellow, red or blue algae that conquered the surface? Simply because the green algae were the best adapted to receive and capture the light that hit them.
Thus, once established on land, photosynthetic organisms with green pigmentation were perfectly prepared to get as much energy as possible. They were thus able to develop, expand and prevail over all other forms of pigmentation, which were unable to adapt to life outside the sea and were forced to remain underwater.
In short: we already know that the plants around us have that characteristic green colour because it allows them to better absorb light for photosynthesis.
can you imagine what the tone of their "skin" would be if they had a different feeding system or if the sunlight had a different frequency? surely they would have different colours and we would now be wondering why plants are pink or blue instead of green!