Editing Vernation

{{short description|New leaf or frond development in botany}}
{{Distinguish|Venation (botany){{!}}Venation}}
'''Vernation''' or '''leafing'''<ref>{{citation |contribution-url=https://www.merriam-webster.com/dictionary/leafing |contribution=leaf |url=https://www.merriam-webster.com |title=Merriam-Webster |date=2023 }}.</ref> is the formation of new [[leaf|leaves]] or [[frond]]s. In plant anatomy, it is the arrangement of leaves in a [[bud]].

In [[pine]] species, new leaves are short and encased in [[Leaf sheath|sheath]]s. Each leaf bundle consists of two to five needles.{{citation needed|date=February 2025}}  All the leaves on one section of branch grow in length together. In [[cabbage]] species, new leaves are folded over, each covered by the previous leaf.{{citation needed|date=February 2025}}

==Name<span class="anchor" id="Etymology"></span><span class="anchor" id="Meaning"></span><span class="anchor" id="Origin"></span><span class="anchor" id="Names"></span>==
The term ''vernation'' is [[linguistic borrowing|borrowed]] from [[New Latin]] {{lang|la|{{linktext|vernatio}}}}, the act of being verdant or flourishing ({{lang|la|[[:wikt:verno#Latin|vernare]]}}). It is [[linguistic cognate|cognate]] with {{lang|la|{{linktext|ver}}}} ([[Latin language|Latin]] for "[[spring (season)|spring]]") and {{lang|la|{{linktext|vernalis}}}} ("vernal").

==Circinate vernation==

{{anchor|circinate}}
[[File:Circinate_vernation.jpg|thumb|upright|This fern is producing a new frond by circinate vernation.]]

'''Circinate vernation''' is the manner in which most [[fern]] fronds emerge.  As the fern frond is formed, it is  tightly curled so that the tender growing tip of the frond (and each subdivision of the frond) is protected within a coil. At this stage it is called a [[crozier]] (after the [[shepherd]]'s crook) or [[fiddlehead]] (after the [[scrollwork]] at the top of a violin). As the lower parts of the frond expand and toughen up, they begin to [[Photosynthesis|photosynthesize]], supporting the further growth and expansion of the frond. By photosynthesizing, the frond increases the amount of solute inside the frond, which lowers the internal water gradient and facilitates an increase in volume that forces uncoiling. In the case of many fronds, long hairs or scales provide additional protection to the growing tips before they are fully uncoiled. Circinate vernation may also be observed in the extension of [[leaflet (botany)|leaflets]], in the [[compound leaves]] of [[cycads]].<ref>{{Cite web |url=http://ponnvandu.wordpress.com/category/circinate-vernation/ |title=Circinate vernation}}</ref> Circinate vernation is also typical of the carnivorous plant family [[Droseraceae]],<ref name="cameron">{{citation |doi=10.3732/ajb.89.9.1503 |title=Molecular evidence for the common origin of snap-traps among carnivorous plants |year=2002 |author=Cameron, K. M. |journal=American Journal of Botany |volume=89 |issue=9 |pages=1503–1509 |last2=Wurdack |first2=K. J. |last3=Jobson |first3=R. W. |pmid=21665752}}</ref> for example see [[:File:Drosera filiformis ne1.jpg|this photo]] of  ''[[Drosera filiformis]]''. It is also seen in the related genera ''[[Drosophyllum]]'' and ''[[Triphyophyllum]]'', and in the much more distantly related ''[[Byblis (plant)|Byblis]]''; however in these three genera, the leaves are coiled ''outwards'' towards the abaxial surface of the leaf (reverse circinate vernation): this appears to be unique to these three plants among the angiosperms.<ref>{{cite book |last1=Ellison |first1=Aaron M. |last2=Adamec |first2=Lubomír |title=Carnivorous plants: physiology, ecology, and evolution |date=2018 |publisher=Oxford University Press |location=Oxford, UK |isbn=978-0198779841 |page=30}}</ref> {{clear}}

==Convolute vernation==
{{anchor|convolute}}[[Image:Convolute_vernation.jpg|thumbnail|This [[hosta]] leaf is produced by ''convolute vernation''.]]
The process of '''convolute vernation''' involves the wrapping of one margin of the leaf's blade over the other. This folding mechanism makes the emerging leaf look like a tube. {{clear}}

==Involute vernation==
{{anchor|involute}}[[Image:Involute_vernation.jpg|thumbnail|These [[cycad]] leaves are produced by ''involute vernation''.]]
In '''involute vernation''' both margins on opposing sides of the leaf are rolled up towards the upper (axial) surface of the leaf, forming two tubes that may meet at the [[midrib]] of the leaf.{{clear}}

==Revolute vernation==
{{anchor|revolute}}'''Revolute vernation''' is the opposite of involute vernation: the margins of the leaf are rolled up towards the under (abaxial) surface of the leaf.<ref name=Been10>{{Citation |last=Beentje |first=Henk |year=2010 |title=The Kew Plant Glossary |publication-place=Richmond, Surrey |publisher=[[Royal Botanic Gardens, Kew]] |isbn=978-1-84246-422-9 |page=101 }}</ref>

== See also ==
* [[Aestivation (botany)|Aestivation]] — the way in which the [[petal]]s and [[sepal]]s of a flower are arranged in a bud.
* [[wikt:ptyxis|Ptyxis]] — the way an individual leaf is folded within a bud.

==References==
{{reflist}}

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[[Category:Leaf morphology]]