Oak

The oak can reach a height of 45 m and a trunk diameter of several meters. Oaks can become up to 2000 years old. In Germany, oaks are the most widespread deciduous tree species after beech, accounting for 9 percent of the population in the lowlands and hills. Oaks love warm, humid regions. In Germany there are mainly the pedunculate or summer oak, the holm 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 a high-quality timber.

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

All parts of the oak, especially immature acorns, are poisonous because of the tanning agents they contain and can lead to gastrointestinal symptoms (irritation of the stomach lining, vomiting, diarrhoea). Oak is used as a medicinal plant because of its tanning agents. Fresh oak bark is collected in spring. Dried and ground, it is used to make a decoction that can be used externally or as tea (never more than two cups a day!). Extracts of oak bark are used externally as a bath or compress (see oak bark below). Oak bark extracts contain tannin, tannic acid, tannins (see also tannin), bitter substances, gallic acid, quercine, quercetin. They have astringent, antibacterial, haemostatic and anti-inflammatory effects. Indications: eczema, chronic wounds, blepharitis, hyperhidrosis, tinea pedis. The flower of the oak tree is used as Bach Flower Oak (see below Bach Flower Therapy).

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