Quercus subg. Cerris

{{Short description|Subgenus of the genus Quercus}} {{Automatic taxobox |image = Quercus cerris.JPG |image_caption = ''[[Quercus cerris]]'' (type species) |taxon = Quercus subg. Cerris |authority = Oerst.<ref name=DenkGrimManoDeng17/> |subdivision_ranks = Sections |subdivision = *''Quercus'' sect. ''Cyclobalanopsis'' Oerst. *''Quercus'' sect. ''Ilex'' Loudon *''Quercus'' sect. ''Cerris'' Dumort. |subdivision_ref = <ref name=DenkGrimManoDeng17/> }}

'''''Quercus'' subgenus ''Cerris''''' is one of the two [[Subgenus|subgenera]] into which the genus ''[[Oak|Quercus]]'' was divided in a 2017 classification (the other being [[Quercus subg. Quercus|subgenus ''Quercus'']]). It contains about 140 species divided among three [[Section (botany)|section]]s. It may be called the Old World clade or the mid-latitude clade; all species are [[Native species|native]] to [[Eurasia]] and [[North Africa]].

==Description== Like all species of ''Quercus'', those of subgenus ''Cerris'' are trees or shrubs with [[acorn]]-like fruit in which a cup covers at least the base of the nut. Members of subgenus ''Cerris'' are distinguished from members of subgenus ''Quercus'' by few morphological features, their separation being largely determined by [[Molecular phylogenetics|molecular phylogenetic]] evidence. The structure of the mature pollen is one feature that distinguishes the two subgenera: in subgenus ''Cerris'', the small folds or wrinkles (rugulae) are visible or at most weakly obscured, whereas in subgenus ''Quercus'', the rugulae are obscured by [[sporopollenin]].<ref name=DenkGrimManoDeng17/>

The two subgenera are also distinguished to some extent by their different distributions. Subgenus ''Cerris'' is primarily [[Eurasia]]n, with a few species in [[North Africa]], and may be called the Old World clade or the mid-latitude clade. Subgenus ''Quercus'' occurs mainly in the Americas (although some species are also found in Eurasia and North Africa), and may be called the New World clade or the high-latitude clade.<ref name=DenkGrimManoDeng17/>

==Taxonomy== ''Quercus'' subgenus ''Cerris'' was first established by [[Anders Sandøe Ørsted (botanist)|Anders Sandøe Ørsted]] in 1867. However, his conception and that of later workers, who often reduced it to a section, was closer to the modern section ''Cerris'' than the wider [[Circumscription (taxonomy)|circumscription]] that has resulted from molecular phylogenetic studies, in which the subgenus is one of two divisions of the genus ''Quercus'', and includes three sections.<ref name=DenkGrimManoDeng17/>

===Phylogeny=== The following [[cladogram]] summarizes the relationships that Denk et al. used to draw up their 2017 classification:<ref name=DenkGrimManoDeng17/>

{{clade |label1=''Quercus'' |1={{clade |1=subg. ''Quercus'' |2={{clade  |label1=subg. ''Cerris'' |1={{clade |1=sect. ''Cyclobalanopsis'' |2={{clade |1=sect. ''Ilex'' |2=sect. ''Cerris'' }} }} }} }} }}

===Section ''Cyclobalanopsis''=== {{See also|List of Quercus species#Section Cyclobalanopsis|l1=List of ''Quercus'' species#Section ''Cyclobalanopsis''}} ''Quercus'' sect. ''Cyclobalanopsis'' was first established, as the genus ''Cyclobalanopsis'', by [[Anders Sandøe Ørsted (botanist)|Anders Sandøe Ørsted]] in 1867.<ref name=IPNI_331537-2>{{IPNI |mode=cs2 |taxon=Cyclobalanopsis |authority=Oerst. |id=331537-2 |access-date=2023-02-24}}</ref> It was first reduced from a genus to a section by [[George Bentham]] and [[William Jackson Hooker]] in 1880. It has also been treated as a subgenus. Members may be called cycle-cup oaks,<ref name=DenkGrimManoDeng17/> or ring-cup oaks.

Like all species of ''Quercus'', those of section ''Cyclobalanopsis'' are trees or shrubs with acorn-like fruit. The [[Plant reproductive morphology#Variations|staminate flowers]] are arranged in groups of usually one to three, but sometimes up to seven, along the axis of the [[inflorescence]]. The ornamentation of the mature [[pollen]] is a distinguishing feature of the section: pollen grains have vertical folds (rugulae). The stalk that joins the [[perianth]] to the [[Ovary (botany)|ovary]] (the perianthopodium) has three to five distinct rings. The 'cup' (cupule) around the base of acorn also has distinct rings formed from thin membranes (lamellae), which also distinguishes the section from other oaks. The leaves are evergreen.<ref name=DenkGrimManoDeng17/>

The section contains about 90 species native to tropical and subtropical Asia including the southern Himalayas.<ref name=DenkGrimManoDeng17/>

<gallery mode="packed" heights="160px"> File:黃背櫟 Quercus championii -香港西貢獅子會自然教育中心 Saikung, Hong Kong- (9219901913).jpg|Catkins of ''[[Quercus championii]]'' in [[Hong Kong]] File:Quercus lamellosa.jpg|Illustration of ''[[Quercus lamellosa]]'' with acorns File:Quercus miyagii.JPG|''[[Quercus miyagii]]'' in habitat File:Chêne au bois de Vaires.jpg|''[[Quercus sessilifolia]]'' in cultivation in France File:Arisan Oak 2016.png|Leaves and acorns of ''[[Quercus stenophylloides]]'' </gallery>

===Section ''Ilex''=== {{See also|List of Quercus species#Section Ilex|l1=List of ''Quercus'' species#Section ''Ilex''}} ''Quercus'' sect. ''Ilex'' was first established by [[John Claudius Loudon]] in 1838. It has also been treated as a subgenus, under the name ''Quercus'' subg. ''Heterobalanus'' Oerst., and as subsection. Members may be called ilex oaks.<ref name=DenkGrimManoDeng17/>

Like all species of ''Quercus'', those of section ''Ilex'' are trees or shrubs with acorn-like fruit. The [[Stamen#Sexual reproduction in plants|staminate flowers]] have four to six stamens. The ornamentation of the mature [[pollen]] is distinctive, consisting of wrinkles or folds (rugulae). The acorns mature either annually or after two years. The cup of the acorn has triangular scales, usually thin and membranous. The toothed leaves are evergreen with spines or bristles at the ends of the teeth.<ref name=DenkGrimManoDeng17/>

The section contains about 40 species native to Eurasia and North Africa.<ref name=DenkGrimManoDeng17/>

<gallery mode="packed" heights="160px"> File:Golden oak.JPG|''[[Quercus alnifolia]]'' File:Quercus coccifera.jpg|Acorns of ''[[Quercus coccifera]]'' File:Quercus floribunda.jpg|''[[Quercus floribunda]]'' File:Quercus ilex0.jpg|Leaves and catkins of ''[[Quercus ilex]]'' File:Quercus ilex rotundifolia.jpg|''[[Quercus rotundifolia]]'' </gallery>

===Section ''Cerris''=== {{See also|List of Quercus species#Section Cerris|l1=List of ''Quercus'' species#Section ''Cerris''}}

''Quercus'' section ''Cerris'' was first established by [[Barthélemy Charles Joseph Dumortier]] in 1829. It has been treated as a section under other names, including ''Quercus'' sect. ''Erythrobalanopsis'' Oerst., ''Quercus'' sect. ''Castaneifolia'' O.Schwarz, ''Quercus'' sect. ''Vallonea'' O.Schwarz, ''Quercus'' sect. ''Aegilops'' (Reichenb.) O.Schwarz and the [[Nomen illegitimum|illegitimate name]] ''Quercus'' sect. ''Eucerris'' Oerst. Members may be called cerris oaks.<ref name=DenkGrimManoDeng17/>

Like all species of ''Quercus'', those of section ''Cerris'' are trees or shrubs with acorn-like fruit. The [[Stamen#Sexual reproduction in plants|staminate flowers]] have four to six stamens. The ornamentation of the mature [[pollen]] is distinctive, consisting of scattered small bumps (verrucate). The cup of the acorn has narrowly triangular scales, thickened and with a keel and elongated recurved tips. The leaf is toothed, typically with bristle-like extensions to the teeth.<ref name=DenkGrimManoDeng17/>

There are about 13 species in Eurasia and North Africa,<ref name=DenkGrimManoDeng17/> including the cork oak, ''[[Quercus suber]]'',<ref name=Denk17App21/> an important source of [[Cork (material)|cork]] for wine stoppers,<ref name=Halliday/> among other uses. It is the only oak section with a centre of diversity in the [[Western Palaearctic|Western Palearctic]].<ref>{{Cite journal |last1=Simeone |first1=Marco Cosimo |last2=Cardoni |first2=Simone |last3=Piredda |first3=Roberta |last4=Imperatori |first4=Francesca |last5=Avishai |first5=Michael |last6=Grimm |first6=Guido W. |last7=Denk |first7=Thomas |date=2018 |title=Comparative systematics and phylogeography of Quercus Section Cerris in western Eurasia: inferences from plastid and nuclear DNA variation |journal=PeerJ |volume=6 |article-number=e5793 |doi=10.7717/peerj.5793 |issn=2167-8359 |pmc=6195796 |pmid=30356975 |doi-access=free }}</ref>

<gallery mode="packed" heights="160px"> File:Цер 13.jpg|''[[Quercus cerris]]'' in autumn File:Quercus cerris 5.jpg|Acorns of ''Quercus cerris'' File:Gland and cupule of Valonia oak - panoramio.jpg|Acorn of [[Quercus ithaburensis subsp. macrolepis|''Quercus ithaburensis'' subsp. ''macrolepis'']], the valonia oak File:Quercus libani port.jpg|''[[Quercus libani]]'' File:Denuded cork oak (2874384025).jpg|Trunk of ''[[Quercus suber]]'', the cork oak, after harvesting </gallery>

==Conservation== The 2020 ''Red List of Oaks'' shows that within the species assessed across all eight sections of the genus ''Quercus'', the sections ''Cyclobalanopsis'' and ''Ilex'' have the largest proportions of species put into the "[[Critically Endangered|critically endangered]]" category, representing the highest level of threat.<ref name=CarrJeroBeckByrn20/> A large number of section ''Cyclobalanopsis'' species occur in China: the ''Flora of China'' states that 69 are native to China of which 43 are endemic.<ref name=FoC/> China has the largest number of threatened oak species.<ref name=CarrJeroBeckByrn20/>

==References== {{Reflist|refs= <ref name=CarrJeroBeckByrn20>{{Citation |last1=Carrero |first1=Christina |last2=Jerome |first2=Diana |last3=Beckman |first3=Emily |last4=Byrne |first4=Amy |last5=Coombes |first5=Allen J. |last6=Deng |first6=Min |last7=González Rodríguez |first7=Antonio |last8=Sam |first8=Hoang Van |last9=Khoo |first9=Eyen |last10=Nguyen |first10=Ngoc |last11=Robiansyah |first11=Iyan |last12=Rodríguez Correa |first12=Hernando |last13=Sang |first13=Julia |last14=Song |first14=Yi-Gang |last15=Strijk |first15=Joeri |last16=Sugau |first16=John |last17=Sun |first17=Weibang |last18=Valencia-Ávalos |first18=Susana |last19=Westwood |first19=Murphy |date=2020 |title=The Red List of Oaks 2020 |publication-place=Lisle, IL |publisher=The Morton Arboretum |url=https://static1.squarespace.com/static/557dec57e4b0c3993deb6044/t/60ba66607de08b6cc5e42d00/1622828642301/RedListOaks2020.pdf |access-date=2023-02-24 |name-list-style=amp }}</ref>

<ref name=DenkGrimManoDeng17>{{Citation |last1=Denk |first1=Thomas |last2=Grimm |first2=Guido W. |last3=Manos |first3=Paul S. |last4=Deng |first4=Min |last5=Hipp |first5=Andrew L. |title=Oaks Physiological Ecology. Exploring the Functional Diversity of Genus Quercus L |series=Tree Physiology |date=2017 |volume=7 |editor1-last=Gil-Pelegrín |editor1-first=Eustaquio |editor2-last=Peguero-Pina |editor2-first=José Javier |editor3-last=Sancho-Knapik |editor3-first=Domingo |contribution=An Updated Infrageneric Classification of the Oaks: Review of Previous Taxonomic Schemes and Synthesis of Evolutionary Patterns |pages=13–38 |publication-place=Cham. |publisher=Springer International Publishing |doi=10.1007/978-3-319-69099-5_2 |isbn=978-3-319-69099-5 |contribution-url=https://doi.org/10.1007/978-3-319-69099-5_2 |name-list-style=amp }}</ref>

<ref name=Denk17App21>{{Citation |last1=Denk |first1=Thomas |last2=Grimm |first2=Guido W. |last3=Manos |first3=Paul S. |last4=Deng |first4=Min |last5=Hipp |first5=Andrew L. |date=2017-11-02 |title=Appendix 2.1: An updated infrageneric classification of the oaks |website=figshare |doi=10.6084/m9.figshare.5547622.v1 |url=https://figshare.com/articles/dataset/Appendix_2_1_________An_updated_infrageneric_classification_of_the_oaks/5547622/1 |access-date=2023-02-17 |format=xls |name-list-style=amp }}</ref>

<ref name=Halliday>{{Citation |last1=Halliday |first1=James |title=Wine bottle closures |publisher=Halliday Wine Companion |url=https://www.winecompanion.com.au/resources/australian-wine-industry/wine-bottle-closures |access-date=2023-02-24 }}</ref>

<ref name=FoC>{{citation |first1=Chengjiu |last1=Huang |first2=Yongtian |last2=Zhang |first3=Bruce |last3=Bartholomew |contribution=Cyclobalanopsis |contribution-url=http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=108828 |access-date=2023-02-24 |editor-last=Wu |editor-first=Zhengyi |editor2-last=Raven |editor2-first=Peter H. |editor3-last=Hong |editor3-first=Deyuan  |title=Flora of China ''(online)'' |publisher=eFloras.org |url=http://www.efloras.org/flora_page.aspx?flora_id=2 |name-list-style=amp }} </ref> }}

{{taxonbar|from1=Q116884314|from2=Q6123078|from3=Q116858648|from4=Q116884274}}

[[Category:Quercus| subg. Cerris]] [[Category:Plant subgenera]]