Evolutionary History:
– Betulaceae originated in central China at the end of the Cretaceous period.
– The region had a Mediterranean climate due to the proximity of the Tethys Sea.
– All six genera and 52 species are native to this region, with many being endemic.
– Modern genera diverged fully by the Oligocene, with a fossil record dating back at least 20 million years.
– Molecular phylogeny suggests Casuarinaceae are the closest relatives of Betulaceae.
Uses:
– Common hazel and filbert are grown for their edible nuts.
– Various genera are popular ornamental trees in parks and gardens.
– Betulaceae wood is hard, tough, and heavy, with hornbeams being particularly robust.
– Some species were historically important for items like cartwheels and tool handles.
– Wood uses have shifted to metal or man-made materials in modern times.
Subfamilies and Genera:
– Betulaceae has two subfamilies: Betuloideae and Coryloideae.
– Betuloideae includes Alnus and Betula.
– Coryloideae includes Carpinus, Corylus, Ostrya, and Ostryopsis.
Extant Species:
– Alnus (alder) and Betula (birch) are part of Betuloideae.
– Carpinus (hornbeam), Corylus (hazel), Ostrya (hop-hornbeam) are in Coryloideae.
– Ostryopsis is another genus in Coryloideae.
This article includes a list of general references, but it lacks sufficient corresponding inline citations. (March 2013) |
Betulaceae, the birch family, includes six genera of deciduous nut-bearing trees and shrubs, including the birches, alders, hazels, hornbeams, hazel-hornbeam, and hop-hornbeams numbering a total of 167 species. They are mostly natives of the temperate Northern Hemisphere, with a few species reaching the Southern Hemisphere in the Andes in South America. Their typical flowers are catkins and often appear before leaves.
| Betulaceae Temporal range:
| |
|---|---|
| |
| Black alder (Alnus glutinosa) | |
Scientific classification 
| |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Fagales |
| Family: | Betulaceae Gray |
| Type genus | |
| Betula | |
| Subfamilies and genera | |
|
See text | |
| |
| The range of the Betulaceae | |
In the past, the family was often divided into two families, Betulaceae (Alnus, Betula) and Corylaceae (the rest). Recent treatments, including the Angiosperm Phylogeny Group, have described these two groups as subfamilies within an expanded Betulaceae: Betuloideae and Coryloideae.
Betulaceae flowers are monoecious, meaning that they have both male and female flowers on the same tree. Their flowers present as catkins and are small and inconspicuous, often with reduced perianth parts. These flowers have large feathery stamen and produce a high volume of pollen, as they rely on wind pollination. Their leaves are simple, with alternate arrangement and doubly serrate margins.