Everything about Betulaceae totally explained
Betulaceae, or the
Birch Family, includes six genera of
deciduous nut-bearing
trees and
shrubs, including the
birches,
alders,
hazels,
hornbeams and
hop-hornbeams, numbering about 130 species. They are mostly natives of the temperate
Northern Hemisphere, with a few species reaching the
Southern Hemisphere in the
Andes in
South America.
In the past, the family was often divided into two families, Betulaceae (
Alnus, Betula) and Corylaceae (the rest); however, recent treatments, including the
Angiosperm Phylogeny Group, have renamed these two groups as subfamilies within the Betulaceae-
Betuloideae and
Coryloideae.
The closest relatives of the Betulaceae are believed to be the
Casuarinaceae, or the She-Oaks.
Evolutionary History
The Betulaceae are believed to have originated at the end of the
Cretaceous period (c. 70 million years ago) in
central China. This region at the time would have had a
Mediterranean type climate due to the proximity of the
Tethys Sea, which covered parts of present-day
Tibet and
Xinjiang into the early
Tertiary period. This point of origin is supported by the fact that all six genera and 52 species are native to this region, many of those being
endemic. It is believed that all six modern genera had diverged fully by the
Oligocene, with all genera in the family (with the exception of
Ostryopsis) having a
fossil record stretching back at least 20 million years from the present.
Uses
The
Common Hazel Corylus avellana and the
Filbert Corylus maxima are important
orchard plants, grown for their edible
nuts.
The other genera include a number of popular
ornamental trees, widely planted in parks and large gardens; several of the birches are particularly valued for their smooth, brightly coloured
bark.
The
wood is generally hard, tough and heavy, hornbeams particularly so; several species were of significant importance in the past where very hard wood capable of withstanding heavy wear was required, such as for
cartwheels,
water wheels,
cog wheels,
tool handles, chopping boards and wooden pegs. In most of these uses wood has now been replaces by
metal or other man-made materials.
Further Information
Get more info on 'Betulaceae'.
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