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Oak is a majestic tree belonging to the genus Quercus, or to the vast family of oaks. The tree is mainly widespread in northern and southern Europe, with a strong prevalence in mountainous and hilly areas. It is a deciduous species, that is deciduous, able to survive and thrive even at altitudes between three hundred and eighteen hundred meters. In Italy, it is widespread especially in the valleys of the Alps and the Pre-Alps. In southern Italy, on the other hand, that is, in Basilicata, Calabria, Puglia and Sicily, the tree is found at altitudes of a thousand meters and in fresh and damp woods. Unlike other oaks, oak is less common on public parks and gardens, because it is mainly used for its precious and highly sought-after wood. Like all oaks, oak is also a very long-lived tree. Some specimens reach even a thousand years of life and many exceed abundantly five hundred years.
Oak, the scientific name Quercus petraea, is an imposing tree belonging to the Fagaceae family, the same as beech and chestnut. Apparently it looks similar to the common oak, that is English, but with slight morphological differences regularly distributed over the whole plant. Unlike the English oak, for example, the acorns of Quercus petraea do not have a stalk, so they are sessile. Because of this characteristic, the oak is also called "sessile oak", while the oak (quercus robur) is called "pedunculate oak". The plant shows a high and majestic foliage that tends to expand very much in width. The foliage of the mature tree can be even twenty meters wide. The trunk is straight, slender, robust and can reach heights between twenty and forty meters. The bark is gray and smooth in the first twenty years of the tree's life, then it tends to fill with longitudinal and horizontal fissures that look like plaques. The main branches, ie the central ones, are gnarled, intertwined and ascending and form, together with the trunk, a sort of acute angle. Even the lateral twigs are particularly intertwined and spectacular and intersect, always forming acute angles. Green in spring, these branches tend to turn gray with the passing of the seasons.
Leaves, flowers and oak fruits
The oak leaves are deciduous and with colors that vary according to their position on the plant and to the amount of light they absorb. The leaf apparatus of the tree is generally of a coriaceous green or lighter green color, smooth and hairless on the upper and lower side. The margins of the leaves are lobed, with five and eight lobes, but more regular than those of the oak. The presence of the lobes perfectly arranged one after the other, also gives the leaf a pleasant wavy edge. The oak flowers are both male and female and like in the English oak, they are present in the same plant. The male ones are carried at the apex of the branches of the previous year and are yellow, the female ones, carried on the apex of the twigs of the year, or on the leaf axil, are collected in groups of two to five flowers and are carried by ears very short. Leaves and flowers appear in the same period, from April to May. The fruits are the acorns. These, in the back, are covered by a woody cap marked by scales, while for the rest they have a smooth surface and a greenish and yellow color which tends to become brown with aging. Unlike the English oak, the acorns of Quercus petraea are sessile, that is without a peduncle. Before reaching the ability to reproduce, he must have reached the age of fifty. In fact, the acorns appear only in the adult plant. In the latter one can witness an abundant production of fruits, even 50 thousand for each season.
Exposure, climate and terrain
Oak, like all oaks, loves sunny exposures, which are used for the maturation of acorns. The young plant, on the other hand, needs a half-shade exposure to develop. The ideal climate for shrub cultivation is temperate and humid. Ideally, rains would be distributed regularly throughout the year, especially during the growing season. The tree is also resistant to low temperatures (even if lower than in the English) and drought and arid land. Resistance to drought is truly exemplary. The plant, in fact, thanks to its very long and robust root system, manages to penetrate deeply into the soil and absorb the water of the underground water table. Quercus petraea likes slightly acidic and well drained soils. The tree can also develop on stony soils, provided they have the right degree of drainage and humidity. Because of the characteristic of growing on stone soils, the scientific name of oak is "quercus petraea".
The Quercus petraea is multiplied by sowing the acorns. These, within two months of collection, are to be buried on vases to be placed outdoors. Sowing must take place in autumn or spring. The seedlings are then transplanted into the soil and after two or three years they can be definitively planted. If planted in a sheltered area, the new plants remain green even in winter. The planting of the plant can always take place in spring or autumn, but on soils excavated at eighty or a hundred centimeters deep and with good drainage.
In the young plant the so-called breeding pruning is carried out, which consists in the defoliation of the plants that present defects. This pruning serves to promote the growth of oak with straight and flawless stems. In the meantime, we have to hoe the soil, which involves cutting and re-mixing the surface layer of the soil to encourage aeration of the roots. The adult tree, on the other hand, should be pruned to limit the expansion of the foliage. This, extending too far, tends to remove light from nearby plants and trees.
Pests, diseases and adversities
Secular oak is very resistant to pests and diseases. Like all oaks, the plant is rather vulnerable at a young age. The parasites that attack the oak are the larvae of a moth and an insect called "cerambicide cerambix cerdo". The first devour the leaves, while the second devastates the wood of the branches and trunk. The shrub can also be affected by some viral diseases, including the well-known "mosaic of the oak", which causes patches of mosaic on the leaves, and of basidiomycete fungi, which cause rotting in the wood. However, Quercus petraea seems to be rather resistant to attacks from other fungal diseases, such as, for example, powdery mildew or the "oak decay syndrome". Furthermore, the acorns are often eaten by wild boars and pigs. One of the worst adversity for the plant is the risk of extinction. In some parts of Europe, more and more are scarce and the woods populated by the homonymous trees are more and more sparse. The rapid extinction of this secular species, in part still inexplicable, is probably due to the massive deforestation activities, the use of tree wood, much sought after due to its high quality and ornamental yield, and to the different destinations of the woodlands. , many of which are now used as pastures. Even in Italy, oak woods are less and less numerous. Oak is also very important for the balance of the ecosystem. Suitable for living alone or in groups, the tree lives in complex plant environments composed of other trees, shrubs, plants, fungi and insects. Its extinction, therefore, risks compromising the life of other species that survive thanks to its presence.
Oak is especially known for the high quality of its wood. This is hard, with a solid and well homogeneous structure, clear, heavy and simple to work. Due to its remarkable value, oak is used in the production of furniture, parquet and wall coverings. Although not present in parks and gardens, oak is a plant with an undeniable ornamental effect. Because of its size and grandeur, the tree can be used as a shading plant or as a windbreak. Combined with other evergreen trees, oak creates a pleasant chromatic contrast and an impenetrable protective hedge.
Also the oak includes different varieties more or less known and valuable. Among these we remember the "Laciniata crispa", a very rare, precious and particular variety. The tree is smaller than classic oak and the trunk does not exceed ten meters in height. The leaves are long, narrow, curled and hang from the branches. Another variety of oak is the "Purpurea", with a fifteen meter high trunk and purple leaves. Another variety to remember is the “Mespilifolia” oak, with less lobed leaves than classic oak. The latter appear in the spring.
Oak: History and symbols
The Quercus petraea has accompanied some important historical events. In 403, near Calcedonia, in the shadow of a large oak tree, a synod was held where the deposition of St. John Chrysostom, the then bishop of Constantinople, was decided. The synod was then called "Synod of the Oak". In 1952, in France, an oak was removed that dated back to 1572, the year of the night of San Bartolomeo and for this reason renamed "Quercia di San Bartolomeo". During the summer of 1859, Giuseppe Garibaldi rested in the shade of an oak tree located near a noble villa. This tree, called "Quercia di Garibaldi", is still present in Milan. Quercus petraea is also a tree that symbolizes strength and plays a particular role in the culture and folklore of ancient peoples. Because of its majesty, it is also considered the tree that gave rise to the life of man on earth.
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