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Birch (Betula)

Family:

Birch family (Betulaceae)

Flowering period:

April-May (June)

Distribution:

generally widespread in Europe, missing in the Mediterranean climate, less so in the south, predominant in the north (birch forests), with low expectations on soil quality and low habitat requirements, frost- resistant, no pests , populating barren and disturbed areas quickly, lusty after full daylight, most important pioneer tree species in Europe

Appearance:

deciduous, trees or shrubs that are green in summer, bark often striking white and black, simple leaves usually alternate, leaves delta-shaped to oval or elliptical to almost circular with pinnate venation Fiedernervatur, leaf edges are sorted by type and are usually doubly serrate (less often waved to roundish lobed), the female inflorescences are usually solitary upright (ovoid to cylindrical), the male inflorescences = catkins hanging individually and in small groups, usually at the ends of the branches

Important species in Europe:

Betula pendula (silver birch): widespread over Central Europe and the boreal zone, often used as ornamental, both B. pendula and B. pubescens frequently hybridize

Betula pubescens (downy birch): found higher than other birch species, to about 2000m above sea level (colline up to subalpine zone).

Betula nana (dwarf birch): dwarf shrub found at higher elevations in Central Europe, on peat soils and in the northern part of Europe (taiga, tundra).

Betula humilis: occurs mainly in moor forests.

Allergenicity:

highly allergenic, most important tree pollen allergen, frequent cross-reactions to pollen from hazel, alder, hornbeam, and members of the Fagales order. Risk factor for pollen associated food allergies (such as apples, stone fruits, nuts, carrots ... ), major allergen Bet v 1 named after Betula verrucosa (now Betula pendula), North American and East Asian species appear to be less allergenic

Link zum Pollenatlas: Betula pendula

Wissenschaftlicher Beirat:
Ass. Prof. Dr. Siegfried Jäger (Medizinische Universität Wien)
Univ. Prof. Dr. Reinhart Jarisch (Floridsdorfer Allergie Zentrum)
Mag. Matthias Werchan (Charité Berlin)
Prof. Dr. med. Karl-Christian Bergmann (Charité Berlin)

Quellen:

Österreichischer Pollenwarndienst, Medizinische Universität Wien, Österreich
Charité, Allergie-Zentrum-Charité, Klinik für Dermatologie, Venerologie und Allergologie, Berlin, Deutschland
Wikipedia
www.alles-zur-allergologie.de
22 Jahre Blüh- und Fruktifikationsuntersuchungen der Waldbaumarten im Lehrforst Ofenbach/Rosalia. R. Litschauer. 2010. Bundesforschungs- und Ausbildungszentrum für Wald, Naturgefahren und Landschaft, BFW-Berichte 144, 36 pp.
Waldbau auf soziologisch-ökologischer Grundlage. H. Mayer 1977. Gustav Fischer Verlag, Stuttgart – New York, 482 pp.

flowering, male catkins (Image rights: Katharina Bastl)
flowering, male catkins (Image rights: Katharina Bastl)
fading flowering catkin, leaves of the birch and the typical white and black bark in the background (Image rights: Katharina Bastl)
fading flowering catkin, leaves of the birch and the typical white and black bark in the background (Image rights: Katharina Bastl)
seed head (Image rights: Katharina Bastl)
seed head (Image rights: Katharina Bastl)
dormant catkins in autumn and winter time (Image rights: Katharina Bastl)
dormant catkins in autumn and winter time (Image rights: Katharina Bastl)
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