2023-11-18 21:00:00
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Starting in October, when temperatures begin to drop and the cold begins to be a common factor in daily life, it is normal to see that the tones of the environment begin to change as well: the days become grayer and the trees take on tones. orange and yellow. However, if we look closely, we can see that It doesn’t happen the same way. for all types of plants, and there are only some that lose their particular green, what then differentiates one from the others?
Well, those trees that maintain greenish tones throughout the year, regardless of whether it is summer or winter, are known as perennialswhile those that are characterized by having leaves that do change color and end up falling, are identified as deciduous. The distinction between one and the other, which determines the drooping of the eyes in the cold months, is simply based on the presence or absence of resins that protect chlorophyll throughout the year.
Video: The 7 species of tallest trees on the planet
GOODBYE TO CHLOROPHYLL
But what is chlorophyll? Well, it is a bright green pigment present in plants and fundamental in the process of photosynthesis, that is, in the process by which plants manage to create food from the capture of sunlight. In fact, chlorophyll is precisely the substance that allows the Sun’s rays to be absorbed by the leaves, allowing the chemical reaction to begin.
However, chlorophyll is an element very delicate, which needs certain very specific conditions to be produced. Therefore, when the rainy and cold seasons begin, the generation of chlorophyll is affected by this change in meteorological conditions, and it progressively decreases, in proportion to how aggressive the climatic situation becomes. The outcome of this phenomenon is the complete disappearance of the substance during the winter, thus eliminating the green that characterizes the leaves of the trees.
Beech forests, much more than a population of trees
Trees that are within the perennial category have an advantage over the rest: their leaves are covered in a special resin. With this characteristic pigment, chlorophyll is not exposed to the harshness of the environment, its production is not altered, and the leaves look a healthy green color throughout the year.
A CURIOUS HIBERNATION
Now, for deciduous trees, the end of chlorophyll also means the end of photosynthesis. That is, the cessation of production of this pigment is identified with a stoppage in the production of food and energy, which represents a very high risk for the survival of the plant. Therefore, trees that meet these types of requirements fall into a survival status during the winter months, in which chlorophyll is not being produced.
iStock
Microscopic view of chloroplasts, which contain chlorophyll, present in a plant leaf.
What does that state consist of? Well, in safeguarding and storing the maximum amount of energy and water they can, to survive throughout the winter with their reserves. To do this, these trees need to get rid of all those elements that are not essential at that moment, that is, the leaves. Without chlorophyll and without a photosynthesis process, leaves simply become areas with no function which, in addition, would be consuming resources to guarantee the survival of the cells that make them up. For this reason, the tree itself gets rid of them.
In this way, between the stem and the branches a series of cells begin to grow that act almost as if they were a complementary layer of the tree itself. By advancing through the branches, they manage to provoke the separation of leaveswhich break off and fall to the ground, leaving the tree without extra energy expenditure and guaranteeing its survival throughout the winter.
Photosynthesis, the great invention of evolution
FROM ORANGE TO YELLOW
Despite this, the fact that chlorophyll disappears and the green color disappears in deciduous trees would still not completely explain where exactly the orange and yellow tones of the leaves come from. And, really, these have their origin in other complementary substances They are found in the leaves, so they are always present, only during the summer months the chlorophyll manages to mask them completely.
Thus, the orange and yellowish colors are due to the presence of a pigment known as carotenoidswhile the intense red that some leaves present is produced by the anthocyanins. The first corresponds to a group of substances among which is, for example, vitamin A, and which also help ensure that photosynthesis occurs smoothly and without difficulties. For its part, anthocyanin is somewhat less known and it is not known exactly what its function is: it could be anything from protection against sunlight to a substance with antioxidant or antifreeze properties.
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