Q uercus petraea, oak or sessile oak, is a species of large trees belonging to the Fagaceae family. Originally from the high regions of Europe, it is located from the Iberian Peninsula to Scandinavia.
It is a common tree in mountainous areas, where it groups together to form dense forests with their own ecosystems. It constitutes a kind of traditional roots in many civilizations, being officially the national tree of Ireland.
Quercus petraea. Source: imagenesmy.com
The structure of the tree is oval or rounded, extensive and regular, with intermediate spaces that allow the passage of light, so the surface under the trunk exhibits a diversity of shrubs that contribute to the biodiversity of oak forests.
Its maximum growth and development potential is expressed in drained, slightly deep and moderately acidic soils. It is a species that adapts to shady conditions, so it adapts to montane ecosystems.
The excellent quality sessile oak wood has been used for centuries as a raw material in the naval industry. Likewise, it is used in the elaboration of slats for construction, and in cabinetmaking to make furniture.
On the other hand, the leaves and acorns are used as fodder and feed for livestock. In addition, the bark with a high tannin content is used in the tanning of hides.
Tradition has given medicinal properties to the bark, leaves and acorns. Indeed, it favors the cure of inflammations, kidney problems and stomach discomfort.
characteristics
Quercus petraea is a tall tree, averaging 30-40 m, forming dense forests. The strong and straight trunk has a thick bark, brown to grayish in color, which tends to crack in long-lived plants.
The leaf area is abundant and unfolded with inflexible straight branches made up of multiple twigs. In effect, it is a deciduous species, that is, each year it loses all its foliage during autumn and winter.
It has simple and alternate leaves, obovate and lobed, with the base of the blade devoid of apricots, and visible fasciculate hairs on the underside. Of variable sizes, between 5-21 cm long by 2-15 cm wide, with cracked edges and oval outline.
The leaves show a dark green color through the back, lighter on the underside that is pubescent in appearance. They are characterized by a 1.5-2.5 cm long petiole, wedge-shaped at one end and lacking a ventricle.
Oak Leaf (Quercus petraea). Source: flickr.com
The female flowers appear in early spring and are born on the branches when they are one year old, with very short peduncles. The male flowers are racemose inflorescences or catkins, usually pendant, characteristic of species of the Fagaceae family.
The ovoid acorn-shaped fruits unfold from autumn. The acorns have a short peduncle, formed by a cocoon with abundant scales, of brown color.
The root system is of the pivoting type, it can reach more than 1.5 meters deep, so it prefers loose and deep soils. It develops a broad system of strong secondary roots for several meters in all directions.
Taxonomy
- Kingdom: Plantae
- Subkingdom: Viridiplantae
- Underkingdom: Streptophyta
- Superdivision: Embryophyta
- Division: Tracheophyta
- Subdivision: Spermatophytina
- Class: Magnoliopsida
- Superorder: Rosanae
- Order: Fagales
- Family: Fagaceae
- Genus: Quercus L. - chêne, oak
- Species: Quercus petraea (Matt.) Liebl.
Of the species Quercus petraea (Matt.) Liebl. Two subspecies have been described:
- Quercus petraea (Matt.) Liebl. subsp. petraea
- Quercus petraea (Matt.) Liebl. subsp. Huguetiana
The subspecies petraea, small leaves, with fewer veins (5-8), little apparent, with flat acorn scales. The huguetian subspecies, large leaves with a greater number of nerves (1-12), visible, and with the acorn scales of a gibbous shape.
Distribution and habitat
The Quercus petraea species is widely distributed from northern Spain to Scandinavia, and from Ireland to the Black Forest in Germany. Its natural habitat is the plains located in elevational floors from 300 to 1,800 meters above sea level.
Albar Oak Forest. Source: wikimedia.org
In Spain it is located towards the north, from Galicia to Catalonia, through León, Palencia, Santander and Navarra. Little abundant in the Central Pyrenees and is found with a certain density in the Gerona Pyrenees and in the Montseny Massif.
It grows on land with slightly sloping topography such as slopes and hills, little exposed to solar radiation. It develops effectively in loose, deep and calcareous soils, even when it adapts to stony, dry and siliceous soils.
Its pluviometric requirements range from 400-600 mm in flowering and fruiting, to at least 150 mm during the summer. In relation to temperature conditions, it can withstand average values of -5º during winter, although it avoids summer environments.
It is a montane species that establishes unique forests or in harmony with pine, beech, fir or other species of oak. It is not very common in valleys or steep areas, with organic soils, where other species have a more dynamic development.
Reproduction
Albear oak (Q. petraea) is mainly propagated by seeds that are collected from the same plant when it is desired to reforest. It is a monoecious unisexual species, in each plant the female and male reproductive structures are located.
Quercus petraea (Sessile Oak) acorns. Source: flickr.com
However, each flower individually possesses the female or gynoecium structure, or the male or androecium structure. It is anemophilic, pollination is guaranteed by dispersion through the wind, and alogamous, where cross pollination and fertilization between different plants predominate.
The female flowers develop in spring, singly or in groups, red on the small branches. The male ones are hanging green inflorescences forming a small grouping of bracts, similar to cocoons.
Flowering begins from April to May, after pollination the flowers turn into bright seeds. In fact, ripening is completed between September and October, forming an ovoid acorn with thick and brownish scales.
The beginning of seed production is reached when the tree is 40 to 100 years old. Its fruiting is annual, but the best productivity and abundance depends on the environmental and intrinsic conditions of the plant.
References
- Acedo, C. (2004). Taxonomy of the genus Quercus L. Species present in the Iberian Peninsula.
- Eaton, E., Caudullo, G., Oliveira, S., & De Rigo, D. (2016). Quercus robur and Quercus petraea in Europe: distribution, habitat, usage and threats. European Atlas of Forest Tree Species, edited by: San-Miguel-Ayanz, J., de Rigo, D., Caudullo, G., Houston Durrant, T., and Mauri, A., Publication Office of the European Union, Luxembourg, 160-163.
- López, MJF, Anta, MB, Álvarez, P., Álvarez, BLV, & Fernández, JAG (2012) Quercus petraea (Matt.) Liebl.
- Quercus petraea (Matt.) Liebl. (2018) ITIS Report. Recovered at: itis.gov
- Quercus petraea: Sessile oak (2018) ArbolApp. Recovered at: arbolapp.es.