Oak

The oak can reach a height of 45 m and a trunk diameter of several meters. Oaks can live for up to 2000 years. In Germany, oaks are the most widespread deciduous tree species after beeches, accounting for 9 percent of the population in flat and hilly areas. Oaks love warm, humid regions. In Germany there are mainly the pedunculate or summer oak, the holm oak or winter oak and the downy oak - in North America the genus Quercus.

The lobed leaves are characteristic, as is the thick bark on the trunk. The 10 cm thick bark of the cork oak (Quervus suber) is used for further processing into cork. Otherwise, the oak provides high-quality timber.

The dried bark of fresh, young oak branches (oak bark - Quercus cortex) is mainly used phytotherapeutically.

All parts of the oak, especially unripe acorns, are poisonous due to the tannins they contain and can lead to gastrointestinal symptoms (irritation of the stomach lining, vomiting, diarrhea). Oak is used as a medicinal plant due to its tannins. Fresh oak bark is collected in spring. Dried and ground, a decoction is made from it, which is used both externally and as a tea (never more than two cups a day!). Oak bark extracts are used externally as a bath or poultice (see oak bark below). Oak bark extracts contain tannin, tannic acid, tannins (see also tannin), bitter substances, gallic acid, quercin, quercetin. They have astringent, antibacterial, hemostatic and anti-inflammatory effects. Indications: eczema, chronic wounds, blepharitis, hyperhidrosis, tinea pedis. The oak flower is used as the Bach flower Oak (see Bach flower therapy below).

From an allergological point of view, oak pollen plays only a minor role (see below pollen, tree pollen).

Of clinical relevance is the infestation of oak trees by the oak processionary moth. The Oak Processionary Moth, which is increasingly found in Central Europe, is exclusively found on oaks. The larvae of the Oak Processionary Moth carry poisonous hairs which cause toxic and/or allergic reactions on the skin and mucous membranes. The symptoms range from severe itching skin rashes ( caterpillar dermatitis) to asthma attacks. As the microscopic poisonous hairs can be carried by the wind up to a hundred metres away, they are an important, until now little noticed cause of " Airborne Contact Dermatitis".

1. https://arzneipflanzenlexikon.info/eiche.php
2. Wenigmann M. (2017) Phytotherapy medicinal drugs, phytopharmaceuticals, application. Urban & Fischer, pp. 99-101