Editing Quercus petraea (section)

== Description ==
{{More references|section|date=October 2024}}
The sessile oak is a large [[deciduous]] [[tree]] up to {{convert|40|m|abbr=off}} tall,<ref>{{Cite journal |last1=Annighöfer |first1=Peter |last2=Beckschäfer |first2=Philip |last3=Vor |first3=Torsten |last4=Ammer |first4=Christian |date=2015 |editor-last=Zang |editor-first=RunGuo |title=Regeneration patterns of European oak species (Quercus petraea (Matt.) Liebl., Quercus robur L.) in dependence of environment and neighborhood. |journal=PLOS ONE |volume=10 |issue=8 |at=e0134935 |doi=10.1371/journal.pone.0134935|pmid=26266803 |pmc=4534096 |bibcode=2015PLoSO..1034935A |doi-access=free }}</ref> in the [[white oak]] section of the genus (''Quercus'' sect. ''Quercus'') and similar to the [[pedunculate oak]] (''Q. robur''), with which it overlaps extensively in range. The [[leaves]] are {{convert|7|-|14|cm|abbr=off|frac=4}} long and {{convert|4|-|8|cm|abbr=on|frac=2}} broad, evenly lobed with five to six lobes on each side and a {{convert|1|cm|in|abbr=on|adj=mid|frac=4|-long}} [[Petiole (botany)|petiole]]. The male [[flower]]s are grouped into [[catkin]]s, produced in the spring. The [[fruit]] is an [[acorn]] {{convert|2|-|3|cm|abbr=on|frac=4}} long and {{convert|1|-|2|cm|abbr=on|frac=4}} broad, which matures in about six months.

<gallery mode=packed heights=170px>
File:Divljanski stari hrast.jpg|Old sacred oak ([[zapis]]) in [[Divljana]], [[Serbia]]
File:Quercus petraea 02.jpg|Shoot with leaves and acorn
File:Eglinton fish pond island inosculated Q. petraea.JPG|An [[inosculation|inosculated]] tree
File:Sessile Oak forest.jpg|A sessile oak in a forest

</gallery>

=== Comparison with pedunculate oak ===
Significant [[botany|botanical]] differences from [[pedunculate oak]] (''Q.&nbsp;robur'') include the stalked leaves, and the stalkless (sessile) [[acorn]]s from which one of its common names is derived. (With the pedunculate oak, it is the acorns which are pedunculate, i.e. on stalks, while the leaves are not.) It occurs in upland areas of altitudes over {{convert|300|m|ft|0|abbr=on}} with higher rainfall and shallow, acidic, sandy soils. Its [[Botanical name#Binary name|specific epithet]] ''petraea'' means "of rocky places".<ref name="RHSLG">{{cite book|last=Harrison|first=Lorraine|title=RHS Latin for gardeners|year=2012|publisher=Mitchell Beazley|location=United Kingdom|isbn=9781845337315|pages=224}}</ref> ''Q.&nbsp;robur'', on the other hand, prefers deeper, richer soils at lower altitude. Fertile [[Hybrid (biology)|hybrids]] with ''Quercus robur'' named ''[[Quercus × rosacea]]'' are found wherever the two parent species occur and share or are intermediate in characters between the parents.{{citation needed|date=October 2024}}

[[Charles Darwin]], in Chapter II of ''[[On the Origin of Species]]'', noted that the sessile and pedunculate oaks had been described as both distinct species and mere varieties depending on the authority consulted.