Autumn arrives and the trees begin to change color, they go from being green to being yellow or brown and even red. Winter arrives and all its leaves fall, leaving them naked and their intense colors disappearing. But wait a minute, there are green trees despite the cold outside, how can that be? Well, if you have ever asked yourself that question, the answer is that what you are seeing is the adaptations of plants to environmental conditions. According to this, deciduous plants and evergreens can be differentiated. We are going to talk about the differences between evergreen and deciduous plants to better understand why we see these color contrasts during the year.
What are deciduous plants
The plants deciduous or deciduous leaf are those whose leaves emerge when the time comes unfavorable (usually winter). The unfavorable season is usually the one in which there are fewer nutrients available and fewer hours of light.
The leaves are the photosynthetic organs par excellence in plants, that is, they are responsible for providing organic matter to the plant through photosynthesis. During the winter there are fewer hours of light and the plants cannot make enough food, so the production of photosynthesis is lower and finally the leaf is lost.
The green color of the leaves is due to the presence of chlorophyll in plant cells. Normally the leaves turn yellow before falling, which means that the plant has stopped producing chlorophyll. Thanks to chlorophyll, plants can photosynthesize, therefore, if there is no chlorophyll, there is no photosynthesis.
In addition, plants have substances that regulate internal processes, plant hormones or phytohormones. Abcisic acid (ABA) is a phytohormone that intervenes in the processes of leaf fall. The plant detects that the environmental conditions are unfavorable and begins to synthesize ABA that is transported to the leaves, when the leaves contain a large amount of ABA the leaf finally falls.
The fall of the leaves is an adaptation to the environment in which they live. Atlantic forests are normally deciduous.
What are evergreens
The plants Evergreens are those whose leaves do not come off during the worst times. These trees also change their leaves throughout their life, but they do not do so with the same frequency as deciduous trees, and also the change of the leaves does not have to occur in unfavorable times. Evergreen leaves are those that last at least two years on the plant.
Remembering the above, if the fall of the leaves is an adaptation to the environment, then the maintenance of the leaves in the unfavorable season is also an adaptation. Changing all the foliage, every year is a task that requires a great energy expenditure for the plant, and depending on the conditions in which it lives, it may or may not be done. Evergreen plants prefer to keep their leaves in winteror during the unfavorable season because they need to feed at all times. However, deciduous plants should make a great effort to keep their leaves alive in unfavorable conditions, that is why they prefer to get rid of them and enter a dormant state, and when the favorable season arrives and the environmental conditions are better. they will be able to grow their foliage again.
Evergreen plants must endure the poor environmental conditions of the unfavorable season. To do this, they have developed a series of adaptations . Some leaves, like those of holm oaks, are small and have hairs to prevent frostbite in cold winters and loss of water in hot summers. Pines, for example, have transformed their leaves into pointed needle-shaped needles, which are also hard due to the presence of waxes that provide protection against the cold.
Usually evergreen plants are found in areas with constant climates, whether hot or cold. For example, tropical plants or high mountain plants both have evergreens. However, deciduous plants are located in climates where there are more favorable periods and others less favorable.
What are marcescent and semi-deciduous plants
Finally, it is worth noting the existence of two more types of leaves . We could say that it is an intermediate state between the two previous ones: they are the plants with marcescent and semi-deciduous leaves :
- The plants with marcescent leaves are those that renew the foliage every year, but do not do so in the unfavorable season. It is an adaptation to climates with late frosts. The leaves of these plants lose their functionality in the unfavorable season, however, they retain them throughout the winter until the new favorable season. This helps them protect the new buds that will form the leaves, both from late frosts and herbivores, as they do not taste good. Once the environmental conditions have arrived, the new leaves push the old ones and they fall.
- The plants semicaduca sheet are those that slow the growth of leaves when conditions become unfavorable. They can generate smaller leaves, change their color or throw them away permanently. When conditions improve, growth resumes and they turn green again.