Quercus

Quercus (from the Latin quercus, which also designated oak, holm oak and cork oak) It is a genus of trees belonging to the fagaceae family.

Description

They are generally large trees, although shrubs are also included. There are permanent foliage, deciduous and marcescent. The male flowers are borne in catkins, complex pendulous inflorescences, usually each flower with four to ten stamens, most often six, long filaments. The female flowers appear isolated or organized in spikes or heads, have three stigmas, as well as anatropous ovules, and are surrounded by a structure of slate scales that, when ripe, will be the dome that will form the acorn. The fruit is called an acorn, it is solitary and of axial (bud) origin, with flat cotyledons. The bark is usually smooth in young specimens but cracks with age maturity. It is considered a genus of ancient origin, with fossils known from the Lower Cretaceous. Its species have been of great value to human communities, due to their wood, bark, obtaining tannins rich in tannins, edible fruits, etc. They participate as dominant elements of the arboreal landscape in many territories of their area of distribution (mainly in the northern hemisphere). Hybridization phenomena between their species are frequent, which usually present, in addition, facility for vegetative regeneration by root or vine shoots.

Fruits of the Quercus pyrenaica

Fruit

The fruit is an acorn that bears in the fall and falls in the winter. Later in spring, if the soil has some penetration, an appendage appears to form the root, called an embryo, and finally opens to begin to develop the stem.

Distribution

The Great Oakby Gustave Courbet (1843)

Genus comprising between 400 and 600 species, distributed throughout Europe, western Asia, North America (especially in the Madrean forests) and South America. Mexico is the country with the largest number of Quercus species (locally called oak) in the world, with around 125, being the most common tree genus in that nation. The same occurs in the United States and Canada, where there are about 60 species. 45 species can be found in Central America, 1 in Colombia and 1 in Cuba.

One of the most appreciated members of the genus Quercus is the oak Quercus robur, which is the dominant forest species on the Atlantic slope of Europe. This species is called carballo in Galicia, carbayu in Asturias, cajiga in Cantabria and haritza in the Basque. Another species with a similar ecology is the sessile oak Quercus petraea. Oaks grow in moist soils, which is why in the Iberian Peninsula they only abound spontaneously in the humid mountain ranges or the northernmost regions. In the Iberian Peninsula they are not usually used in forestry given their slow growth, but their wood is one of the most appreciated.

Among the most widespread Mediterranean species in drier areas of the Iberian Peninsula, the gall oak Quercus pyrenaica stands out, dominant in mountainous areas of the interior of the peninsula (for example: Herrería de El Escorial, Valsaín, Montes de Toledo, Sierra Morena…), and the holm oak Quercus ilex subsp. ballota, very abundant in a multitude of ecological niches in the center and south of the peninsula (eg: Cabañeros National Park (Ciudad Real), Monfragüe National Park (Cáceres), Monte del Pardo (Madrid), Carrascal de la Fuente Roja (Alcoy), Sierra Madrona (Ciudad Real)…).

Classification

The genus Quercus is divided into two subgenera and several sections:

Subgenus Quercus

This subgenre is divided into the following sections:

Quercus Section

Its synonyms are Lepidobalanus and Leucobalanus, these species make up the list of so-called «white oaks» of Europe, Asia and North America. Its gynoeciums are short; the acorns mature in 6 months and its taste is bitter or slightly sweet, the interior of the shell of the acorns is hairless, its leaves mostly lack bristles on their extremities and their lobes are usually rounded. Partial list of some species of oaks (Quercus), belonging to the subgenus Quercus, section Quercus:

Mesobalanus Section

They are known as the "Hungarian oaks" and their relatives from Europe, Asia and North Africa. Long pistils; its acorns mature at 6 months and have a bitter taste; the interior of the dome is hairless. Section Mesobalanus is closely related to section Quercus and has sometimes been included within it.

• Quercus canariensis - Andaluz Oak.
• Quercus dentata - Roble daimio
• Quercus frainetto - Oak of Hungary
• Quercus macranthera - Oak of the Caucasus
• Quercus pontica - Oak of Armenia
• Quercus pyrenaica (no. Quercus nigra- Brush, peach oak, toce, tocia, baroque
• Quercus vulcanica

Cerris Section

The Cerris section is known as the Turkish Oaks and their relatives from Europe, Asia and North Africa. They have a long gynoecium and their acorns mature 18 months after germination but have a very bitter taste. The interior of the shell of the acorns does not have hairs. Its leaves often have sharp-pointed lobes, with bristles on their edges.

• Quercus acutissima - Roble kunigi
• Quercus alnifolia
• Quercus castaneifolia - Persian Oak
• Quercus cerris - Scalp Oak, ridge oak
• Quercus coccifera (no. Quercus calliprinos- Coscojo, coscoja
• Quercus infectoria
• Quercus ithaburensis Decne.
  • Quercus ithaburensis subsp. macrolepis (Kotschy) Hedge & Yalt. - veil of Levante
• Quercus libani
• Quercus macrolepis
• Quercus semecarpifolia
• Quercus suber - Alcornoque (mediterranean)
• Quercus trojana - Roble of Macedonia
• Quercus variabilis - Alcornoque of China

Protobalanus Section

The section of the Protobalanus known as the section of intermediate oaks and its relatives in the southwestern United States and northwestern Mexico. It has short gyneciums, and its acorns mature at 18 months with a very bitter taste. The inside of the shell of acorns is hairy, and their leaves often have sharp-pointed lobes, with bristles at the ends.

• Quercus cedrosensis
• Quercus chrysolepis (no. Quercus oblongifolia) - Blue Mexican Encina
• Quercus palmeri
• Quercus tomentella
• Quercus vaccinifolia

Lobatae Section

The «red oaks» (synonym: subgen.Erythrobalanus). They generally develop in North America, Central America and only one in the northern part of South America. With long pistils and acorns that mature in 18 months, very bitter and with a hairy interior. The nut is encased in a thin, sticky layer of parchment-like skin. The leaves often have sharp-pointed lobes, with spiny hairs on them.

Subgenus Cyclobalanopsis

This subgenus is known as the list of "ring-topped oaks" and occurs mainly in east and southeast Asia. They are "evergreen" They reach heights of between 10 and 40 meters. They are quite different from the subgenus Quercus in that they have acorns with distinctive ringed cups of different size scales and commonly develop in dense groups, although this does not apply to all species. The Flora of China treats Cyclobalanopsis as a separate genus, but most taxonomists consider it to be a subgenus of Quercus. In total there are about 150 species.

Uses

For killing:

Food

Glans type fruit, called an acorn. Some are edible directly raw, such as those of Quercus ilex ssp. ballota, Quercus macrolepis, Quercus vallonea, and Quercus alba. The fruits of many other Quercus can also be consumed through previous processes to eliminate their bitterness. These processes vary from one culture to another (cooking, roasting, leaching, adding sodium bicarbonate, adding clay...).

Industrial

They supply coloring matter Quercus tintoria from North America, whose barks are tintorial, and Quercus coccifera, from the entire Mediterranean region, which produces a coloring matter similar to cochineal.

Pharmacological

Mediterranean species: Quercus infectoria from Asia Minor, and Quercus lusitanica from the western Mediterranean produce galls from the bites of galligenous Hymenoptera, Cynips galleae, in the cambial region of the young shoots; in trade you can find Aleppo gall, Basra gall, etc., which contain 60 to 70% tannic acid, 3% gallic acid and 2% ellagic acid, used as astringents and hemostatics. Gallic acid is obtained from them (by hydrolysis of the tannic), widely used in the manufacture of many pharmaceutical products, as well as for the preparation of blue-black ink.

Botany

The barks of young Quercus (12 to 20 years old), especially Quercus robur in Europe and Quercus prinus in North America, are used therapeutically as astringents contain 16 to 20% tannic acid.

Ancestral uses

Of most Quercus the bark is used as "casca" to tan skins, since they form tannins with the skin proteins, which are imputrescible (sole, leather). In the Iberian Peninsula, the wood of Quercus ilex and that of Quercus pyrenaica have been widely used to produce charcoal.

The Quercus macrocarpa has also been used by the American Indians to treat heart problems, etc.

Construction

The wood of Quercus is one of the most resistant woods, although some species have it too rough (for example Quercus pyrenaica).

It is widely used and valued to achieve quality furniture. In addition, it is used for the manufacture of barrels and container barrels for aging good wine.

In addition, the bark of the cork oak (Quercus suber) is used for the production of cork.

Quercus diseases

In oak galls (Quercus robur and Quercus petraea), produced by cinipeds, the alternating generations of these insects are curious. In autumn the Dryophanta folii, agama or asexual, lays its eggs on the tender shoots and buds of the small winter galls that determine, they come out in the months of April-May, the sexual forms of the ciniped, Dryophanta taschenbergii, which once fertilized lays its eggs on oak leaves producing summer galls, incubators of the asexual form.

In North America, oak roots are frequently attacked by parasitic plants known as "elotillos" (Conopholis alpina and C. americana).

Hybridizations in the Iberian Peninsula

• Q. × andegavensis Hy (Quercus robur x Quercus pyrenaica) (Pulmonary-Quertion theft: 76.4)
• Q. × arrimatensis Penas, Llamas, Pérez Morales & Acedo (Quercus pauciradiata x Quercus petraea) (Quercenion robori-pyrenaicae: 76.7b)
• Q. × calvescens nothosubsp. costae (C.Vicious) Rivas Mart. " Sáenz de Rivas (Quercus petraea x Quercus pubescens subsp. subpyrenaica) (Buxo-Quercenion pubescentis: 76.9a)
• Q. × calvescens Vuk. nothosubsp. calvescens (Quercus petraea x Quercus pubescens subsp. pubescens) (Corylo-Populion tremulae: 76.12)
• Q. × cerrioides Willk. " Costa (Quercus pubescens subsp. subpyrenaica x Quercus faginea subsp. faginea) (Buxo-Quercenion pubescentis: 76.9a)
• Q. × coutinhoi Samp. (Quercus robur x Quercus faginea) (Pulmonary-Quertion theft: 76.4)
• Q. × demotricha O.Schwartz (Quercus pubescens subsp. subpyrenaica x Quercus canariensis) (Buxo-Quercenion pubescentis: 76.9a)
• Q. × jahandiezii nothosubsp. viiosai (Sáenz de Rivas & Rivas Mart.) Rivas Mart. " Sáenz de Rivas (Quercus canariensis x Quercus faginea subsp. alpestris) (Paeonio-Abietion pinsapo: 76.11)
• Q. × kerneri nothosubsp. monserratii (C.Vicious) Rivas Mart. " Sáenz de Rivas (Quercus robur subsp. robur x Quercus pubescens subsp. subpyrenaica) (Buxo-Quercenion pubescentis: 76.9a)
• Q. × kerneri Simkovies nothosubsp. kerneri (Quercus robur subsp. robur x Quercus pubescens subsp. pubescens) (Pulmonary-Quertion theft: 76.4)
• Q. × marianica C. Vicious (Quercus canariensis x Quercus broteroi) (Quercenion broteroi: 75.2a)
• Q. × mixed Villalobos ex Colmeiro (Quercus suber x Quercus rotundifolia) (Quercetalia ilicis: 75a)
• Q. × rosacea Bechst nothosubsp. rosacea (Quercus robur subsp. robur x Quercus petraea) (Quercetalia roboris: 76b)
• Q. × rosacea nothosubsp. secalliana (C.Vicious) Rivas Mart. " Sáenz de Rivas (Quercus robur subsp. broteroana x Quercus petraea) (Quercenion robori-pyrenaicae: 76.7b)
• Q. × rotensis Penas, Llamas, Pérez Morales & Acedo (Quercus pauciradiata x Quercus pyrenaica) (Quercenion pyrenaicae: 76.7a)
• Q. × trabutii Hy (Quercus petraea x Quercus pyrenaica(Luzulo-Quercenion petraeae: 76.8b)

Other hybrids

• Quercus × hispanica Lam. (Quercus cerris x Quercus suber) - mesto arbóreo