The daily repetition of the gestures and actions that leads men to work, to study, to the usual activities, often leaves no time to consider, or appreciate, the great weight that the plants have, not only with regard to the man himself , but also towards all the vital phenomena that take place on Earth. Unlike any animal, which attracts the immediate curiosity of children and adults because basically there are frequent similarities with the human animal, a plant does not always arouse sensations. Sometimes, in fact, one can marvel at the size, the beauty of the flowers, the inebriating perfume, but there is usually indifference towards a green mass in which there is no obvious difference compared to another neighbor. We proceed then considering the green world as a background, a frame in which our life takes place. All this is due to the apparent static nature of the plants with which we have more relationships; the plants, solidly rooted to the ground, live passively towards external changes, unable to react to human destructive interventions or those of atmospheric and natural agents. When a leaf or a flower is torn, not a cry, not a reaction from these strange organisms; only when a tree breaks down, after the noise of the chainsaw and the squeaks, the final thud and the silence that follow them strike the imagination. Although so vulnerable, however, the plants have developed in the course of their history mechanisms that have been able, so far, to overcome almost all critical moments that occur in the life of an organism, claiming a fundamental principle of nature: what matters is the maintenance over time of the species, not of the individual. So infinite adaptations are discovered that often overcome man’s ability to intervene on nature, trying to take away space from what, apparently, is not useful, to favor food, industrial and forest plants. In the alteration of the original equilibrium, however, gaps remain or are always formed, immediately occupied by other or new plants that will be able to fully exploit the space left to them. All this happens without great clamor, often manifesting itself only to specialists; species forgotten until yesterday suddenly become very common weeds, others migrate from distant countries, others disappear because they are missing environments suitable for their survival or because, commonly cultivated once, are no longer required by the market. When we move into our cities, we rarely notice the large foliage of a tree, or disturb the flowering of some ornamental, which drops the corolla faded to “dirty” the cars; then we do not talk about the autumn fall of the crazy chestnuts, which are also able to leave their mark on the expensive (but thin) bodywork. We try to transform that common idea that we have of the lawn: no longer a green carpet, made up of indistinct elements, but a balanced and not random set of different plants, especially with different needs and vital rhythms, with showy or inconspicuous shapes. We try to raise our heads and look at the trees of the avenue: they are often taller than houses, they bear pruning that mutilate them, have their roots covered by the asphalt mantle and succeed, every year, despite everything, to mark the seasons. The culture of our western world is linked through innumerable symbols to the world of plants. In the past, in addition to using vegetables for food, men were united by centuries-old traditions, of which today only pale examples remain: few, in fact, the head of laurel (symbol of victory and wisdom) on the day of graduation, nor brides are adorned with myrtle (symbol of love and happy weddings) on the wedding day; oak leaves and acorns (symbol of wisdom and longevity) are still found in some coat of arms or perhaps in the uniform decorations. We will try through these lines to give some space to the history and importance of what we commonly call plants, because through the knowledge of the diversity of species and the mechanisms that regulate their lives, it will be possible to improve our relationship with the plants. incredible green world.
Life on Earth depends on plants. The Earth, the blue planet, is the only one in the solar system in which there is life today. The fossil record and the succession of different living organisms, in the seas and on the emerged lands, show that the complexity of forms depends directly on the development of the different species of plants. We must shortly clarify some basic concepts: by plant we mean an organism, made up of one or more cells (which are the fundamental building blocks of living matter), capable of photosynthesizing, of producing that substance that can be used by the plant as nourishment.
This production takes place starting from water and carbon dioxide, and exploiting sunlight as a source of energy. While water and carbon dioxide are substances of the inanimate world (inorganic, that is, not exclusive to an organism), the substances produced by living cells are organic, that is, they are found only in organisms. Examples of organic matter are starch, cellulose, sugars, fats, proteins. The organic matter thus produced can also be exploited by other organisms without the ability to photosynthesize (the animals). It is clear, however, that they depend on the quantity of plant matter (primary productivity) that they will consume (first-order consumers); in turn these “herbivores” (in the sense that they feed on plant matter and can be unicellular living in water, worms, molluscs, insects and vertebrates) will become nourishment for other organisms (second-order or predatory consumers), whose life will depend from the presence or absence of first-class consumers; predators of predators (superpredators) also exist. These are placed at the top of the so-called “trophic or food pyramid”, which we can imagine to build by overlapping the biomass (quantity of organic matter produced) in the individual levels. Because in order to keep alive the living of a level, it is necessary to consume a part of the energy that arrives, passing from one level to another the biomass will be gradually smaller. This explains why large predators are always fewer than the prey they feed on. Each element of the various levels depends on the previous level, thus forming a food chain that at the beginning however always has the plants.
It should be emphasized that the passage of substances does not take place only from one level to another, but at every level there are bodies called “restitutors”, which use the remains of plants and living in general, transforming them into simpler substances (decomposition) and returning them to the environment in the form of an inorganic substance (remineralisation); in this sense they are fundamental, as well as numerous decomposers such as insects, worms, fungi, especially many bacteria that make available to the environment again the inorganic materials such as water, carbon dioxide and minerals, used by green plants in the synthesis of organic compounds. In the oceans and in the waters the primary producers are above all microscopic plants, unicellular algae, that constitute the phytoplankton. The food chain of the seas has in these tiny organisms the origin of all the vital phenomena that reach the greatest living beings on Earth, like the blue whale.
How men are related to flowering plants In the terrestrial environments, flowering plants predominate, ie plants that have organized a particular reproduction mechanism that provides for the formation of seeds (see: Pollination, Fertilization). Plants with seeds (Spermatophytes) are the main primary producers of the environment in which the man lives who, as a consumer, depends directly (fruits, seeds, vegetables) or indirectly (products of breeding, hunting). When we think of a flower or a plant, we usually refer to color, shape, smell, underestimating all the other relationships of dependence that exist between plants and man, which uses them as a source of food, materials to construction, textile fibers, medicines. The evolution of human society has produced an extreme division of labor, with a progressive specialization. The primary need, that of nutrition, has been solved, with the development of agriculture, thus allowing to devote a good part of the energy to improve the living standards of the population. The history of man is linked precisely to the ability to produce economically and to accumulate stocks for critical periods. The full granaries in the territories of the fertile crescent (area between the Nile, the eastern Mediterranean coast and the course of Tigris and Euphrates), meant not only wealth, but also, as today, constituted a strategic asset that allowed to keep an army to defense of the territories against the raids of the nomadic raiders. In Jarmo, in the current Iraq, remains of two types of wheat and one of barley have been found, ascribable to 7000 years BC. Agriculture has brought about a great change in the history of man: from collector-hunter, from nomad who followed their prey, he permanently fixed his home, raising animals and cultivating the land. Plants used for fodder for livestock or for human food are all flowering plants or, as we have already pointed out, plants with seeds and fruits. And it is these seeds and fruits that represent the part that can be conserved, rich in substances destined to nourish the seedling when it begins to develop and which instead man uses as his own nourishment.
It is no coincidence that the dawn of civilization saw the cultivation of cereals, not very demanding plants, annuals, easy to preserve as a seed from one year to another and to be transported. But, they say, one does not live by bread alone; man needed tools for agriculture, and these were obtained from the wood of the trees; they served houses and warehouses, then logs and branches; the fire was needed to cook the bread, the food and even the clay with which to make the jars for the conservation of the crops, and the fuel was of vegetable origin. Exchanges were made with the improvement of living conditions; using means of transport more capable than the back of a donkey or a dromedary, with the wood of the trees were built ships (for a long time the transport with wagons would be limited by the lack of roads and the difficulty of tying the animals to the cart itself) . The demands became more and more sophisticated; to the skins of the animals the wool was preferred, then the fabrics of linen and cotton. From the vegetal fibers the ropes were obtained for the ships and the sails that pushed them from a landing to the other, with the holds filled with jars of oil and granary amphorae. The oil squeezed from the olives served, as well as food, also to illuminate the nights of antiquity and to dissolve ointments, balsams and perfumes. From the plants the medicines were obtained to solve the ailments and the illnesses, the surgeons knew the plants to get a quicker and better cicatrizzazione. Precisely the need to correctly recognize medicinal plants will stimulate the birth of that science called botany. The products of flowering plants and their derivatives have accompanied the life of man through his history, providing food and material for his clothes, but also as voluptuous elements or not tied to strict survival; so we think of spices, stimulating drinks like tea or coffee. The selection made on the cultivated plants has allowed to obtain ever better and more efficient varieties, but far from the wild progenitors, such as corn. In corn, the scientists managed to manipulate the genetic make-up with bioengineering procedures; this in order to make the plant, which is unable to do it naturally, produce a certain quantity of an essential substance, the amino acid lysine, which is accumulated in the fruit, thus providing a complete food for humans and animals.