View source for Betulaceae

{{Short description|Family of flowering plants comprising hazel and birch trees}}
{{more footnotes needed|date=March 2013}}
{{Automatic taxobox
|fossil_range = {{fossilrange|70|0}}
|image = Alnus glutinosa.jpg
|image_caption = Black alder (''[[Alnus glutinosa]]'')
|taxon = Betulaceae
|authority = [[John Edward Gray|Gray]]<ref name="apgiii">{{Citation |author=Angiosperm Phylogeny Group |year=2009 |title=An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III |journal=Botanical Journal of the Linnean Society |volume=161 |issue=2 |pages=105–121 |doi=10.1111/j.1095-8339.2009.00996.x |doi-access=free |hdl=10654/18083 |hdl-access=free }}</ref>
|type_genus = ''[[Betula]]''
|type_genus_authority = [[Carl Linnaeus|L.]]
|subdivision_ranks = Subfamilies and genera
|subdivision = See text
|range_map = Betulaceae Distribution.svg
|range_map_caption = The range of the Betulaceae
}}
[[File:Catkins Corylus avellana-Mont Bart-5124~2015 12 26.JPG|thumb|Catkins of the hazel (''[[Corylus avellana]]'')]]

'''Betulaceae''', the '''birch family''', includes six genera of [[deciduous]] [[nut (fruit)|nut]]-bearing [[tree]]s and [[shrub]]s, including the [[birch]]es, [[alder]]s, [[hazel]]s, [[hornbeam]]s, [[Ostryopsis|hazel-hornbeam]], and [[Ostrya|hop-hornbeam]]s, numbering a total of 167 species.<ref name="Christenhusz-Byng2016">{{cite journal |author1=Christenhusz, M. J. M. |author2=Byng, J. W.  |name-list-style=amp | year = 2016 | title = The number of known plants species in the world and its annual increase | journal = Phytotaxa | volume = 261 | pages = 201–217 | url = http://biotaxa.org/Phytotaxa/article/download/phytotaxa.261.3.1/20598 | doi = 10.11646/phytotaxa.261.3.1 | issue = 3 | publisher = Magnolia Press | doi-access = free |bibcode=2016Phytx.261..201C }}</ref> 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.

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.

==Evolutionary history==
The Betulaceae are believed to have originated at the end of the [[Cretaceous]] period (about 70 million years ago) in [[Sichuan Province|central China]]. This region at the time would have had a [[Mediterranean 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 [[endemism|endemic]]. All six modern genera are believed to have 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.

According to [[molecular phylogeny]], the closest relatives of the Betulaceae are the [[Casuarinaceae]], or the she-oaks.<ref name="soltis2011">{{cite journal | vauthors = Soltis DE, Smith SA, Cellinese N, Wurdack KJ, Tank DC, Brockington SF, Refulio-Rodriguez NF, Walker JB, Moore MJ, Carlsward BS, Bell CD, Latvis M, Crawley S, Black C, Diouf D, Xi Z, Rushworth CA, Gitzendanner MA, Sytsma KJ, Qiu YL, Hilu KW, Davis CC, Sanderson MJ, Beaman RS, Olmstead RG, Judd WS, Donoghue MJ, Soltis PS | year = 2011 | title = Angiosperm phylogeny: 17 genes, 640 taxa | journal = [[American Journal of Botany|Am J Bot]] | volume = 98 | issue = 4 | pages = 704–730 | doi = 10.3732/ajb.1000404| pmid = 21613169 | bibcode = 2011AmJB...98..704S | s2cid = 8204080 | hdl = 2027.42/142064 | hdl-access = free }}</ref>

==Uses==
[[Image:Corylus avellana.jpg|right|thumb|''[[Corylus avellana]]'' foliage and nuts]]
The common hazel (''[[Corylus avellana]]'') and the filbert (''[[Corylus maxima]]'') are important [[orchard]] plants, grown for their edible [[nut (fruit)|nuts]].

The other genera include a number of popular [[ornamental plant|ornamental trees]], widely planted in parks and large gardens; several of the birches are particularly valued for their smooth, brightly coloured [[Bark (botany)|bark]].

The [[wood]] is generally hard, tough and heavy, [[hornbeam]]s 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 [[cart]]wheels, [[water wheel]]s, [[gear|cog wheels]], [[tool]] handles, chopping boards, and wooden pegs. In most of these uses, wood has now been replaced by [[metal]] or other man-made materials.

==Subfamilies and genera==
===Extant genera===
*Betuloideae
**''[[Alnus]]'' <small>Mill. 1754</small> – alder
**''[[Betula]]'' <small>L. 1753</small> – birch
*[[Coryloideae]]
**''[[Carpinus]]'' <small>L. 1753</small> – hornbeam
**''[[Corylus]]'' <small>L. 1753</small> – hazel
**''[[Ostrya]]'' <small>Scop. 1760</small> – hop-hornbeam
**''[[Ostryopsis]]'' <small>Decne. 1873</small> – hazel-hornbeam

===Fossil genera===
*Betuloidea
**{{extinct}}''[[Alnipollenites]]'' {{small|R. Potonié, 1931}} (pollen)
**†''[[Alnoxylon]]'' {{small|Felix, 1884}} (wood)
**†''[[Alnuspollenites]]'' {{small|Raatz, 1938}} (pollen)
**†''[[Betulapollenites]]'' {{small|R. Potonié, 1937}} (pollen)
**†''[[Betulaepollenites]]'' {{small|R. Potonié, 1934}} (pollen)
**†''[[Paralnoxylon]]'' {{small|Doweld, 2021}} (wood)
*Coryloidea
**†''[[Asterocarpinus]]'' {{small|Manchester & Crane, 1987}} (fruits)
**†''[[Coryloides]]'' {{small|Manchester, 1994}} (fruits)
**†''[[Cranea]]'' {{small|Manchester & Chen, 1998}} (fruits, flowers, pollen & Leaves)
**†''[[Corylocarpinus]]'' {{small|Straus, 1969}} (fruits)
**†''[[Craspedodromophyllum]]'' {{small|P.R. Crane, 1981}} (leaves)
**†''[[Kardiasperma]]'' {{small|Manchester, 1994}} (fruits)
**†''[[Palaeocarpinus]]'' {{small|P.R. Crane, 1981}} (fruits)
**†''[[Paracarpinus]]'' {{small|Manchester & P.R. Crane, 1987}} (leaves)
*''Incertae sedis''
**†''[[Alniphyllum (Nathorst)|Alniphyllum]]'' {{small|Nathorst, 1886}} (leaves)
**†''[[Alnites]]'' {{small|Göppert, 1837}} (leaves, flowers, fruits)
**†''[[Alnophyllum]]'' {{small|Staub, 1884}} (leaves)
**†''[[Betulites]]'' {{small|Göppert, 1837}} (flowers)
**†''[[Betulacites]]'' {{small|Agranovskaja, Botscharnikova, & Martynova, 1960}} (pollen)
**†''[[Betulinium]]'' {{small|Unger, 1842}} (wood)
**†''[[Trivestibulopollenites]]'' {{small|Pflug & P.W. Thomson, 1953}} (pollen)
**†''[[Betuliphyllum]]'' {{small|Dusén in Nordenskjöld, 1899}} (leaves)
**†''[[Betuloidites]]'' {{small|R. Potonié, Thomson, & Thiergart, 1950}} (pollen)
**†''[[Betuloxylon]]'' {{small|Kaiser, 1880}} (wood)
**†''[[Carpinicarpus]]'' {{small|Nikitin, 1966}} (fruits)
**†''[[Carpiniphyllum]]'' {{small|Nathorst ex Krassilov, 1979}} (leaves)
**†''[[Carpinites]]'' {{small|Göppert & Berendt, 1845}} (flowers)
**†''[[Carpinoxylon]]'' {{small|Vater, 1884}} (wood)
**†''[[Carpinuspollenites]]'' {{small|R. Potonié, Thomson, & Thiergart, 1949}} (pollen)
**†''[[Castanopsispollenites]]'' {{small|Thiergart, 1937}} (pollen)
**†''[[Clethrites]]'' {{small|Beuth, 1776}} (wood)
**†''[[Corylipollenites]]'' {{small|R. Potonié, 1934}} (pollen)
**†''[[Corylites]]'' {{small|Gardner, 1887}} (leaves)
**†''[[Coryloidites]]'' {{small|R. Potonié, Thomson, & Thiergart, 1949}} (pollen)
**†''[[Corylophyllum]]'' {{small|J. Dawson, 1888}} (leaves)
**†''[[Coryloxylon]]'' {{small|U. Prakash, Březinová, & Bůžek, 1971}} (wood)
**†''[[Coryluspollenites]]'' {{small|Raatz, 1938}} (pollen)
**†''[[Eucarpinoxylon]]'' {{small|MuellerStoll & Maedel, 1959}} (wood)
**†''[[Ostryoipollenites]]'' {{small|R. Potonié, 1960}} (pollen)
**†''[[Phegites]]'' {{small|C.N. Lange ex J.F. Krüger, 1825}} (wood)
**†''[[Rhizoalnoxylon]]'' {{small|Conwentz, 1880}} (root)
**†''[[Triporopollenites]]'' {{small|Pflug & P.W. Thomson, 1953}} (pollen)

==Phylogenetic systematics==
Modern [[molecular phylogenetics]] suggest the following relationships:<ref name="soltis2011"/><ref>{{cite journal | vauthors = Xiang XG, Wang W, Li RQ, Lin L, Liu Y, Zhou ZK, Li ZY, Chen ZD | year = 2014 | title = Large-scale phylogenetic analyses reveal fagalean diversification promoted by the interplay of diaspores and environments in the Paleogene | journal = Perspectives in Plant Ecology, Evolution and Systematics | volume = 16 | issue = 3 | pages = 101–110 | doi = 10.1016/j.ppees.2014.03.001| bibcode = 2014PPEES..16..101X }}</ref><ref>{{cite journal | vauthors = Chen ZD, Manchester SR, Sun HY | year = 1999 | title = Phylogeny and evolution of the Betulaceae as inferred from DNA sequences, morphology, and palaeobotany | journal = [[American Journal of Botany|Am J Bot]] | volume = 86 | issue = 8 | pages = 1168–1181 | doi=10.2307/2656981| jstor = 2656981 | pmid = 10449397 | doi-access = free }}</ref>

{{Clade| style=line-height:75%;
|1={{clade
  |1=&nbsp;[[Myricaceae]]&nbsp;([[Outgroup (cladistics)|outgroup]])
  |label2=Betulaceae
  |2={{clade
    |label1=[[Coryloideae]]
    |1={{clade
      |1=&nbsp;''[[Corylus]]''
      |2={{clade
        |1=&nbsp;''[[Ostryopsis]]''
        |2={{clade
          |1=&nbsp;''[[Ostrya]]''
          |2=&nbsp;''[[Carpinus]]''
           }}
         }}
       }}
    |label2=Betuloideae
    |2={{clade
      |1=&nbsp;''[[Alnus]]''
      |2=&nbsp;''[[Betula]]''
       }}
     }}
   }}
}}

==References==
{{Reflist|2}}

{{Commons category|Betulaceae}}

{{Angiosperm families}}
{{Taxonbar|from=Q156064}}
{{Authority control}}

[[Category:Betulaceae| ]]
[[Category:Rosid families]]
[[Category:Extant Maastrichtian first appearances]]
[[Category:Taxa named by John Edward Gray]]