| Quercus petraea | 
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| A mature tree | 
|  | 
|  | 
| Scientific classification | 
| Kingdom: | Plantae | 
 
| Clade: | Tracheophytes | 
 
| Clade: | Angiosperms | 
 
| Clade: | Eudicots | 
 
| Clade: | Rosids | 
 
| Order: | Fagales | 
 
| Family: | Fagaceae | 
 
| Genus: | Quercus | 
 
| Subgenus: | Quercus subg. Quercus | 
 
| Section: | Quercus sect. Quercus | 
| Species: | Q. petraea | 
| Binomial name | 
| Quercus petraea 
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| Subspecies | 
| See text. | 
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| Distribution map | 
| Synonyms | 
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Quercus robur var. petraea Matt.
  Quercus brevipedunculata Cariot & St.-Lag. 
  Quercus calcarea Troitsky
  Quercus columbaria Vuk.
  Quercus coriacea Bechst.
  Quercus coronensis Schur
  Quercus decipiens Behlen 
  Quercus dispar Raf. 
  Quercus durinus Raf.
  Quercus erythroneura Vuk.
  Quercus esculus L.
  Quercus longipetiolata Schur
  Quercus mas Thore 
  Quercus mespilifolia Wallr.
  Quercus peraffinis Gand.
  Quercus petiolata Schur
  Quercus regalis Burnett ex Endl. 
  Quercus sessiliflora Salisb.
  Quercus sessilis Ehrh. ex Schur
  Quercus spathulifolia Vuk.
  Quercus sphaerocarpa Vuk.
  Quercus sublobata Kit.
  Quercus huguetiana (Franco & G.López) Rivas Mart.
  Quercus colchica Czeczott
  Quercus dshorochensis K.Koch
  Quercus hypochrysa Steven
  Quercus iberica Steven ex M.Bieb.
  Quercus kochiana O.Schwarz 
  Quercus kozlowskyi Woronow ex Grossh.
  Quercus lamprophyllos K.Koch
  Quercus polycarpa Schur
  Quercus sorocarpa Woronow ex Maleev 
  Quercus szowitzii Wenz.
  Quercus abietum Kotschy ex A.DC.
  Quercus cedrorum Kotschy
  Quercus ibicis Kotschy ex A.DC.
  Quercus pinnatiloba K.Koch 
  Quercus subalpina Kotschy ex A.DC.
  Quercus tergestina Wenz.
  plus a long list of invalid names and another long list of names below the species level
  
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Quercus petraea, commonly known as the sessile oak, Welsh oak, Cornish oak, Irish oak or durmast oak, is a species of oak tree native to most of Europe and into Anatolia and Iran. The sessile oak is the national tree of Ireland, and an unofficial emblem in Wales and Cornwall.