View source for Pinaceae

{{Short description|Family of conifers}}
{{Automatic taxobox
| fossil_range = {{fossil range|Jurassic|Recent}} Possible Triassic record <ref>{{cite web |title=Fort Wingate (Triassic of the United States) |url=https://paleobiodb.org/classic/basicCollectionSearch?collection_no=23968 |website=PBDB.org}}</ref>
| image = Glacier-Lyman-Tamarack.jpg
| image_caption = ''Larix'' (golden), ''Abies'' (central foreground) and ''Pinus'' (right foreground)
| taxon = Pinaceae
| authority = [[John Lindley|Lindley]] 1836
| subdivision_ranks = Genera
| subdivision = * '''[[Abietoideae]]'''
** ''[[Abies]]''
** ''[[Cedrus]]''
** ''[[Keteleeria]]''
** ''[[Nothotsuga]]''
** ''[[Pseudolarix]]''
** ''[[Tsuga]]''
* '''[[Pinoideae]]'''
** ''[[Pinus]]''
* '''[[Piceoideae]]'''
** ''[[Picea]]''
* '''[[Laricoideae]]'''
** ''[[Pseudotsuga]]''
** ''[[Cathaya]]''
** ''[[Larix]]''
| synonyms = * Abietaceae <small>von Berchtold & Presl 1820</small>
* Cedraceae <small>Vest 1818</small>
* Compsostrobaceae <small>Delevoryas & Hope 1973</small>
* †Kranneraceae <small>Corda 1866</small>
* Piceaceae <small>Goroschankin 1904</small>
}}

The '''Pinaceae''' ({{IPAc-en|p|I|'|n|eI|s|i:|%|i:|,_|-|s|i|%|aI}}), or '''pine family''', are [[conifer]] trees or shrubs, including many of the well-known conifers of commercial importance such as [[Cedrus|cedars]], [[fir]]s, [[Tsuga|hemlocks]], [[Pinyon_pine|piñons]],  
[[larch]]es, [[pine]]s and [[spruce]]s. The family is included in the order [[Pinales]], formerly known as [[Coniferales]]. Pinaceae have distinctive cones with woody scales bearing typically two [[Ovule|ovules]], and are supported as [[monophyletic]] by both [[Morphology (biology)|morphological]] trait and genetic analysis.<ref>{{Cite journal |last1=Gernandt |first1=David S. |last2=Holman |first2=Garth |last3=Campbell |first3=Christopher |last4=Parks |first4=Matthew |last5=Mathews |first5=Sarah |last6=Raubeson |first6=Linda A. |last7=Liston |first7=Aaron |last8=Stockey |first8=Ruth A. |last9=Rothwell |first9=Gar W. |date=September 2016 |title=Phylogenetics of extant and fossil Pinaceae: methods for increasing topological stability |url=http://www.nrcresearchpress.com/doi/10.1139/cjb-2016-0064 |journal=Botany |language=en |volume=94 |issue=9 |pages=863–884 |doi=10.1139/cjb-2016-0064 |issn=1916-2790|url-access=subscription }}</ref> They are the largest extant conifer family in species diversity, with between 220 and 250 species (depending on [[Taxonomy (biology)|taxonomic]] opinion) in 11 genera,<ref name="Farjon">{{cite book |author=Aljos Farjon |year=1998 |title=World Checklist and Bibliography of Conifers |publisher=[[Royal Botanic Gardens, Kew]]  |isbn=978-1-900347-54-9}}</ref> and the second-largest (after [[Cupressaceae]]) in geographical range, found in most of the [[Northern Hemisphere]], with the majority of the species in temperate climates, but ranging from subarctic to tropical. The family often forms the dominant component of [[Boreal forest|boreal]], coastal, and [[montane forest]]s. One species, ''[[Pinus merkusii]]'', grows just south of the [[equator]] in Southeast Asia.<ref>{{Gymnosperm Database |family=Pinaceae |genus=Pinus |species=merkusii |access-date=March 17, 2015}}</ref> Major [[centre of diversity|centres of diversity]] are found in the mountains of [[southwest China]], Mexico, central Japan, and [[California]].

==Description==
[[File:Vagamon Pine Forest.jpg|thumb|left|Cultivated pine forest in [[Vagamon]], southern [[Western Ghats]], [[Kerala]], India]]

Members of the family Pinaceae are [[tree]]s (rarely [[shrub]]s) growing from {{convert|2|to|100|m|ft|sigfig=1|abbr=off}} tall, mostly [[evergreen]] (except the [[deciduous]] ''[[Larix]]'' and ''[[Pseudolarix]]''), [[resin]]ous, [[monoecious]], with subopposite or whorled branches, and spirally arranged, linear (needle-like) leaves.<ref name="Farjon"/> The embryos of Pinaceae have three to 24 [[cotyledon]]s.

The female [[conifer cone|cones]] are large and usually woody, {{convert|2|-|60|cm|0|abbr=off}} long, with numerous spirally arranged scales, and two winged [[seed]]s on each scale. The male cones are small, {{convert|0.5|-|6|cm|abbr=on|sigfig=1|frac=4}} long, and fall soon after pollination; pollen dispersal is by wind. Seed dispersal is mostly by wind, but some species have large seeds with reduced wings, and are dispersed by birds. Analysis of Pinaceae cones reveals how selective pressure has shaped the evolution of variable cone size and function throughout the family. Variation in cone size in the family has likely resulted from the variation of seed dispersal mechanisms available in their environments over time. All Pinaceae with seeds weighing less than 90&nbsp;milligrams are seemingly adapted for wind dispersal. Pines having seeds larger than 100&nbsp;mg are more likely to have benefited from adaptations that promote animal dispersal, particularly by birds.<ref>{{cite journal |author=Craig W. Benkman |year=1995 |title=Wind dispersal capacity of pine seeds and the evolution of different seed dispersal modes in pines |journal=[[Oikos (journal)|Oikos]] |volume=73 |issue=2 |pages=221–224 |jstor=3545911 |url=http://www.uwyo.edu/benkman/pdfs%20of%20papers/benkman_oikos_1995.pdf |doi=10.2307/3545911|bibcode=1995Oikos..73..221B }}</ref> Pinaceae that persist in areas where [[tree squirrel]]s are abundant do not seem to have evolved adaptations for bird dispersal.

Boreal conifers have many adaptions for winter. The narrow conical shape of northern conifers, and their downward-drooping limbs help them shed snow, and many of them seasonally alter their biochemistry to make them more resistant to freezing, called "hardening".

==Classification==
[[File:Ab plant 673.jpg|thumb|An immature second-year cone of [[European black pine]] (''Pinus nigra'') with the light brown umbo visible on the green cone scales]]
[[File:Norway Spruce cone.jpg|thumb|An immature cone of [[Norway spruce]] (''Picea abies'') with no umbo]]

Classification of the subfamilies and genera of Pinaceae has been subject to debate in the past. Pinaceae ecology, morphology, and history have all been used as the basis for methods of analyses of the family. An 1891 publication divided the family into two subfamilies, using the number and position of resin canals in the primary vascular region of the young taproot as the primary consideration. In a 1910 publication, the family was divided into two tribes based on the occurrence and type of long–short shoot dimorphism.

A more recent classification divided the subfamilies and genera based on the consideration of features of ovulate cone anatomy among extant and fossil members of the family. Below is an example of how the morphology has been used to classify Pinaceae. 
The 11 genera are grouped into four subfamilies, based on the microscopical anatomy and the morphology of the cones, pollen, wood, seeds, and leaves:<ref>{{cite journal |author=Robert A. Price, Jeanine Olsen-Stojkovich & Jerold M. Lowenstein |year=1987 |title=Relationships among the genera of Pinaceae: an immunological comparison |journal=[[Systematic Botany]] |volume=12 |issue=1 |pages=91–97 |jstor=2419217 |doi=10.2307/2419217}}</ref>

* Subfamily [[Pinoideae]] (''[[Pinus]]''): cones are biennial, rarely triennial, with each year's scale-growth distinct, forming an umbo on each scale, the cone scale base is broad, concealing the seeds fully from [[abaxial]] (below the [[phloem]] vessels) view, the seed is without resin vesicles, the seed wing holds the seed in a pair of claws, leaves have primary stomatal bands adaxial (above the xylem) or equally on both surfaces.
* Subfamily [[Piceoideae]] (''[[Picea]]''): cones are annual, without a distinct umbo, the cone scale base is broad, concealing the seeds fully from abaxial view, seed is without resin vesicles, blackish, the seed wing holds the seed loosely in a cup, leaves have primary stomatal bands adaxial (above the xylem) or equally on both surfaces.
* Subfamily [[Laricoideae]] (''[[Larix]]'', ''[[Pseudotsuga]]'', and ''[[Cathaya]]''): cones are annual, without a distinct umbo, the cone scale base is broad, concealing the seeds fully from abaxial view, the seed is without resin vesicles, whitish, the seed wing holds the seed tightly in a cup, leaves have primary stomatal bands abaxial only.
* Subfamily [[Abietoideae]] (''[[Abies]]'', ''[[Cedrus]]'', ''[[Pseudolarix]]'', ''[[Keteleeria]]'', ''[[Nothotsuga]]'', and ''[[Tsuga]]''): cones are annual, without a distinct umbo, the cone scale base is narrow, with the seeds partly visible in abaxial view, the seed has resin vesicles, the seed wing holds the seed tightly in a cup, leaves have primary stomatal bands abaxial only.

=== Phylogeny ===
A revised 2018 phylogeny places ''Cathaya'' as sister to the pines rather than in the Laricoidae subfamily with ''Larix'' and ''Pseudotsuga''.

{| class="wikitable"
|-
! colspan=1 |Ran et al. 2018<ref>{{Cite journal|last1=Ran|first1=Jin-Hua|last2=Shen|first2=Ting-Ting|last3=Wu|first3=Hui|last4=Gong|first4=Xun|last5=Wang|first5=Xiao-Quan|date=2018-12-01|title=Phylogeny and evolutionary history of Pinaceae updated by transcriptomic analysis|url=http://www.sciencedirect.com/science/article/pii/S1055790318301246|journal=Molecular Phylogenetics and Evolution|language=en|volume=129|pages=106–116|doi=10.1016/j.ympev.2018.08.011|pmid=30153503 |bibcode=2018MolPE.129..106R |s2cid=52110440 |issn=1055-7903|url-access=subscription}}</ref> & Leslie et al. 2018<ref>{{cite journal |last1=Leslie |first1=Andrew B. |last2=Beaulieu |first2=Jeremy |last3=Holman |first3=Garth |last4=Campbell |first4=Christopher S. |last5=Mei |first5=Wenbin |last6=Raubeson |first6=Linda R. |last7=Mathews |first7=Sarah |display-authors=et al. |year=2018 |title=An overview of extant conifer evolution from the perspective of the fossil record |journal=American Journal of Botany |url=https://doi.org/10.1002/ajb2.1143 |volume=105 |issue=9 |pages=1531–1544 | doi=10.1002/ajb2.1143 |pmid= 30157290|pmc= |bibcode= |doi-access=}}</ref><ref>{{cite journal |last1=Leslie |first1=Andrew B. |display-authors=et al. |year=2018 |title=ajb21143-sup-0004-AppendixS4 |journal=American Journal of Botany |volume=105 |issue=9 |pages=1531–1544 |doi=10.1002/ajb2.1143 |url=https://bsapubs.onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1002%2Fajb2.1143&file=ajb21143-sup-0004-AppendixS4.pdf |doi-access=|pmid=30157290 }}</ref>
! colspan=1 |Stull et al. 2021<ref>{{cite journal |last1=Stull |first1=Gregory W. |last2=Qu |first2=Xiao-Jian |last3=Parins-Fukuchi |first3=Caroline |last4=Yang |first4=Ying-Ying |last5=Yang |first5=Jun-Bo |last6=Yang |first6=Zhi-Yun |last7=Hu |first7=Yi  |last8=Ma |first8=Hong |last9=Soltis |first9=Pamela S. |last10=Soltis |first10=Douglas E. |last11=Li |first11=De-Zhu |last12=Smith |first12=Stephen A. |last13=Yi |first13=Ting-Shuang |display-authors=et al. |year=2021 |title=Gene duplications and phylogenomic conflict underlie major pulses of phenotypic evolution in gymnosperms |journal=Nature Plants |url=https://www.nature.com/articles/s41477-021-00964-4 |volume=7 |issue= 8|pages=1015–1025 |doi=10.1038/s41477-021-00964-4|biorxiv=10.1101/2021.03.13.435279 |pmid= 34282286|pmc= |bibcode= 2021NatPl...7.1015S|s2cid=232282918 |doi-access=}}</ref><ref>{{cite web |last1=Stull |first1=Gregory W. |display-authors=et al. |year=2021 |title=main.dated.supermatrix.tree.T9.tre |publisher=Figshare |doi=10.6084/m9.figshare.14547354.v1 |url=https://figshare.com/articles/dataset/Gene_duplications_and_genomic_conflict_underlie_major_pulses_of_phenotypic_evolution_in_gymnosperms/14547354 |doi-access=}}</ref>
|- 
| style="vertical-align:top|
{{clade| style=font-size:90%;line-height:80%;
|1={{clade
  |label1=[[Abietoideae]]
  |1={{clade
    |1={{clade
      |label1=Cedreae
      |1=''[[Cedrus]]'' (cedars 4 sp.)
       }}
    |2={{clade
      |label1=Pseudolariceae
      |1={{clade
        |1=''[[Pseudolarix]]'' (golden larch 1 sp.)
        |2={{clade
          |1=''[[Nothotsuga]]'' (1 sp.)
          |2=''[[Tsuga]]'' (hemlock  9 sp.)
           }}
         }}
      |label2=Abieteae
      |2={{clade
        |1=''[[Keteleeria]]'' (3 sp.)
        |2=''[[Abies]]'' (firs c.50 sp.)
         }}
       }}
     }}
  |label2=[[Pinoideae]]
  |2={{clade
    |label1=Lariceae
    |1={{clade
      |1=''[[Pseudotsuga]]'' (Douglas-firs 5 sp.)
      |2=''[[Larix]]'' (larches 14 sp.)
       }}
    |label2=Pineae
    |2={{clade
      |1=''[[Picea]]'' (spruces c 35 sp.)
      |2={{clade
        |1=''[[Cathaya]]'' (1 sp.)
        |2=''[[Pinus]]'' (pines c.115 sp.)
         }}
       }}
     }}
   }}
}}
|
{{clade| style=font-size:90%;line-height:80%;
|1={{clade
  |label1=[[Abietoideae]]
  |1={{clade
    |1={{clade
      |label1=Cedreae
      |1=''[[Cedrus]]''
       }}
    |2={{clade
      |label1=Pseudolariceae
      |1={{clade
        |1=''[[Pseudolarix]]''
        |2={{clade
          |1=''[[Nothotsuga]]''
          |2=''[[Tsuga]]''
           }}
         }}
      |label2=Abieteae
      |2={{clade
        |1=''[[Keteleeria]]''
        |2=''[[Abies]]''
         }}
       }}
     }}
  |label2=[[Pinoideae]]
  |2={{clade
    |label1=Lariceae
    |1={{clade
      |1=''[[Pseudotsuga]]''
      |2=''[[Larix]]''
       }}
    |label2=Pineae
    |2={{clade
      |1={{clade
        |1=''[[Cathaya]]''
        |2=''[[Picea]]''
         }}
      |2=''[[Pinus]]''
       }}
     }}
   }}
}}
|}

Multiple molecular studies indicate that in contrast to previous classifications placing it outside the conifers, [[Gnetophyta]] may in fact be the sister group to the Pinaceae, with both lineages having diverged during the early-mid [[Carboniferous]]. This is known as the "gnepine" hypothesis.<ref>{{Cite journal|last1=Stull|first1=Gregory W.|last2=Qu|first2=Xiao-Jian|last3=Parins-Fukuchi|first3=Caroline|last4=Yang|first4=Ying-Ying|last5=Yang|first5=Jun-Bo|last6=Yang|first6=Zhi-Yun|last7=Hu|first7=Yi|last8=Ma|first8=Hong|last9=Soltis|first9=Pamela S.|last10=Soltis|first10=Douglas E.|last11=Li|first11=De-Zhu|date=July 19, 2021|title=Gene duplications and phylogenomic conflict underlie major pulses of phenotypic evolution in gymnosperms|url=https://www.nature.com/articles/s41477-021-00964-4|journal=Nature Plants|language=en|volume=7|issue=8|pages=1015–1025|doi=10.1038/s41477-021-00964-4|pmid=34282286 |bibcode=2021NatPl...7.1015S |s2cid=236141481 |issn=2055-0278}}</ref><ref>{{Cite journal|last1=Ran|first1=Jin-Hua|last2=Shen|first2=Ting-Ting|last3=Wang|first3=Ming-Ming|last4=Wang|first4=Xiao-Quan|title=Phylogenomics resolves the deep phylogeny of seed plants and indicates partial convergent or homoplastic evolution between Gnetales and angiosperms|journal=Proceedings of the Royal Society B: Biological Sciences|year=2018 |volume=285|issue=1881|pages=20181012|doi=10.1098/rspb.2018.1012|pmc=6030518|pmid=29925623}}</ref>

=== Evolutionary history ===
Pinaceae is estimated to have diverged from other conifer groups during the late [[Carboniferous]] ~313 million years ago.<ref name="Leslie 2018 1531–1544">{{Cite journal |last1=Leslie |first1=Andrew B. |last2=Beaulieu |first2=Jeremy |last3=Holman |first3=Garth |last4=Campbell |first4=Christopher S. |last5=Mei |first5=Wenbin |last6=Raubeson |first6=Linda R. |last7=Mathews |first7=Sarah |date=2018 |title=An overview of extant conifer evolution from the perspective of the fossil record |url=https://bsapubs.onlinelibrary.wiley.com/doi/abs/10.1002/ajb2.1143 |journal=American Journal of Botany |language=en |volume=105 |issue=9 |pages=1531–1544 |doi=10.1002/ajb2.1143 |pmid=30157290 |s2cid=52120430 |issn=1537-2197}}</ref> Various possible [[stem-group]] relatives have been reported from as early as the Late [[Permian]] ([[Lopingian]]) The extinct conifer cone genus ''[[Schizolepidopsis]]'' likely represent stem-group members of the Pinaceae, the first good records of which are in the Middle-Late [[Triassic]], with abundant records during the [[Jurassic]] across Eurasia.<ref>{{Cite journal |last1=Domogatskaya |first1=Ksenia V. |last2=Herman |first2=Alexei B. |date=May 2019 |title=New species of the genus Schizolepidopsis (conifers) from the Albian of the Russian high Arctic and geological history of the genus |url=https://linkinghub.elsevier.com/retrieve/pii/S0195667118304257 |journal=Cretaceous Research |language=en |volume=97 |pages=73–93 |doi=10.1016/j.cretres.2019.01.012|bibcode=2019CrRes..97...73D |s2cid=134849082 |url-access=subscription }}</ref><ref name=":11">{{Cite journal |last1=Matsunaga |first1=Kelly K. S. |last2=Herendeen |first2=Patrick S. |last3=Herrera |first3=Fabiany |last4=Ichinnorov |first4=Niiden |last5=Crane |first5=Peter R. |last6=Shi |first6=Gongle |date=2021-05-10 |title=Ovulate Cones of Schizolepidopsis ediae sp. nov. Provide Insights into the Evolution of Pinaceae |journal=International Journal of Plant Sciences |volume=182 |issue=6 |pages=490–507 |doi=10.1086/714281 |issn=1058-5893 |doi-access=free}}</ref> The oldest [[crown group]] (descendant of the last common ancestor of all living species) member of Pinaceae is the cone ''[[Eathiestrobus]]'', known from the Upper Jurassic (lower [[Kimmeridgian]], 157.3-154.7 million years ago) of Scotland,<ref>{{Cite journal |last1=Rothwell |first1=Gar W. |last2=Mapes |first2=Gene |last3=Stockey |first3=Ruth A. |last4=Hilton |first4=Jason |date=April 2012 |title=The seed cone Eathiestrobus gen. nov.: Fossil evidence for a Jurassic origin of Pinaceae |journal=American Journal of Botany |language=en |volume=99 |issue=4 |pages=708–720 |doi=10.3732/ajb.1100595 |pmid=22491001}}</ref> which likely belongs to the pinoid grouping of the family.<ref name=":12">{{Cite journal |last1=Smith |first1=Selena Y. |last2=Stockey |first2=Ruth A. |last3=Rothwell |first3=Gar W. |last4=Little |first4=Stefan A. |date=2017-01-02 |title=A new species of Pityostrobus (Pinaceae) from the Cretaceous of California: moving towards understanding the Cretaceous radiation of Pinaceae |url=https://www.tandfonline.com/doi/full/10.1080/14772019.2016.1143885 |journal=Journal of Systematic Palaeontology |language=en |volume=15 |issue=1 |pages=69–81 |doi=10.1080/14772019.2016.1143885 |bibcode=2017JSPal..15...69S |s2cid=88292891 |issn=1477-2019|url-access=subscription }}</ref><ref name=":11" /> Pinaceae rapidly radiated during the [[Early Cretaceous]].<ref name="Leslie 2018 1531–1544" /> Members of the modern genera ''Pinus'' (pines), ''Picea'' (spruce) and ''Cedrus'' (cedar) first appear during the Early Cretaceous.<ref>{{Cite journal |last1=Blokhina |first1=N. I. |last2=Afonin |first2=M. |date=2007 |title=Fossil wood Cedrus penzhinaensis sp. nov. (Pinaceae) from the Lower Cretaceous of north-western Kamchatka (Russia) |journal=Acta Paleobotanica |language=en |volume=47 |pages=379–389 |s2cid=54653621 }}</ref><ref>{{cite journal |author1=Ashley A. Klymiuk |author2=Ruth A. Stockey |name-list-style=amp |year=2012 |title=A Lower Cretaceous (Valanginian) seed cone provides the earliest fossil record for Picea (Pinaceae) |journal=[[American Journal of Botany]] |volume=99 |issue=6 |pages=1069–1082 |doi=10.3732/ajb.1100568 |pmid=22623610 |doi-access=free}}</ref><ref>{{cite journal |author1=Patricia E. Ryberg |author2=Gar W. Rothwell |author3=Ruth A. Stockey |author4=Jason Hilton |author5=Gene Mapes |author6=James B. Riding |year=2012 |title=Reconsidering Relationships among Stem and Crown Group Pinaceae: Oldest Record of the Genus ''Pinus'' from the Early Cretaceous of Yorkshire, United Kingdom |journal=International Journal of Plant Sciences |volume=173 |issue=8 |pages=917–932 |doi=10.1086/667228 |s2cid=85402168}}</ref> The extinct Cretaceous genera ''[[Pseudoaraucaria]]'' and ''[[Obirastrobus]]'' appear to be members of Abietoideae, while ''[[Pityostrobus]]'' appears to be non-monophyletic, containing many disparately related members of Pinaceae.<ref name=":12" /> While Pinaceae, and indeed all of its subfamilies, substantially predate the break up of the super-continent [[Pangaea|Pangea]], its distribution was limited to northern [[Laurasia]].  During the Cenozoic, Pinaceae had higher rates of species turnover than Southern Hemisphere conifers, thought to be driven by range shifts in response to glacial cycles.<ref>{{Cite journal |last1=Leslie |first1=Andrew B. |last2=Beaulieu |first2=Jeremy M. |last3=Rai |first3=Hardeep S. |last4=Crane |first4=Peter R. |last5=Donoghue |first5=Michael J. |last6=Mathews |first6=Sarah |date=2012-10-02 |title=Hemisphere-scale differences in conifer evolutionary dynamics |journal=Proceedings of the National Academy of Sciences |language=en |volume=109 |issue=40 |pages=16217–16221 |doi=10.1073/pnas.1213621109 |doi-access=free |issn=0027-8424 |pmc=3479534 |pmid=22988083|bibcode=2012PNAS..10916217L }}</ref>

== Defense mechanisms ==
External stresses on plants have the ability to change the structure and composition of [[Forest ecology|forest ecosystems]]. Common external stress that ''Pinaceae'' experience are [[herbivore]] and [[pathogen]] attack which often leads to tree death.<ref name=":7">{{Cite journal|last1=Cherubini|first1=Paolo|last2=Fontana|first2=Giovanni|last3=Rigling|first3=Daniel|last4=Dobbertin|first4=Matthias|last5=Brang|first5=Peter|last6=Innes|first6=John L.|date=2002|title=Tree-Life History Prior to Death: Two Fungal Root Pathogens Affect Tree-Ring Growth Differently|jstor=3072253|journal=Journal of Ecology|volume=90|issue=5|pages=839–850|doi=10.1046/j.1365-2745.2002.00715.x|doi-access=free|bibcode=2002JEcol..90..839C }}</ref> In order to combat these stresses, trees need to adapt or evolve defenses against these stresses. ''Pinaceae'' have evolved myriad mechanical and chemical defenses, or a combination of the two, in order to protect themselves against antagonists.<ref name=":1">{{Cite journal|title=Terpenoid biosynthesis and specialized vascular cells of conifer defense. - Semantic Scholar|year=2010|doi=10.1111/j.1744-7909.2010.00910.x|pmid=20074143|s2cid=26043965|last1=Zulak|first1=K. G.|last2=Bohlmann|first2=J.|journal=Journal of Integrative Plant Biology|volume=52|issue=1|pages=86–97|doi-access=free}}</ref> ''Pinaceae'' have the ability to up-regulate a combination of constitutive mechanical and [[Chemical defense|chemical strategies]] to further their defenses.<ref name=":8">{{Cite journal|last1=Franceschi|first1=Vincent R.|last2=Krokene|first2=Paal|last3=Christiansen|first3=Erik|last4=Krekling|first4=Trygve|date=2005-08-01|title=Anatomical and chemical defenses of conifer bark against bark beetles and other pests|journal=New Phytologist|language=en|volume=167|issue=2|pages=353–376|doi=10.1111/j.1469-8137.2005.01436.x|pmid=15998390|issn=1469-8137|doi-access=free}}</ref>

''Pinaceae'' defenses are prevalent in the bark of the trees. This part of the tree contributes a complex defensive boundary against external antagonists.<ref name=":0">Franceschi, V. R., P. Krokene, T. Krekling, and E. Christiansen. 2000. Phloem parenchyma cells are involved in local and distance defense response to fungal inoculation or bark-beetle attack in Norway spruce (''Pinaceae''). American Journal of Botany 87:314-326.</ref> [[Constitutive defense|Constitutive]] and [[Inducible plant defenses against herbivory|induced defenses]] are both found in the bark.<ref name=":0" /><ref name=":6">{{Cite journal|last1=Hudgins|first1=J. W.|last2=Christiansen|first2=E.|last3=Franceschi|first3=V. R.|date=2004-03-01|title=Induction of anatomically based defense responses in stems of diverse conifers by methyl jasmonate: a phylogenetic perspective|journal=Tree Physiology|language=en|volume=24|issue=3|pages=251–264|doi=10.1093/treephys/24.3.251|pmid=14704135|issn=0829-318X|doi-access=free}}</ref><ref name=":9">{{Cite journal|last1=Krokene|first1=P.|last2=Nagy|first2=N. E.|last3=Solheim|first3=H.|date=2008-01-01|title=Methyl jasmonate and oxalic acid treatment of Norway spruce: anatomically based defense responses and increased resistance against fungal infection|journal=Tree Physiology|language=en|volume=28|issue=1|pages=29–35|doi=10.1093/treephys/28.1.29|pmid=17938111|issn=0829-318X|doi-access=free}}</ref>

=== Constitutive defenses ===
[[Constitutive defense]]s are typically the first line of defenses used against antagonists and can include sclerified cells, lignified periderm cells, and secondary compounds such as [[Phenols|phenolics]] and resins.<ref name=":2">{{Cite journal|last=Sampedro|first=L.|date=2014-09-01|title=Physiological trade-offs in the complexity of pine tree defensive chemistry|journal=Tree Physiology|language=en|volume=34|issue=9|pages=915–918|doi=10.1093/treephys/tpu082|pmid=25261122|issn=0829-318X|doi-access=free|hdl=10261/105595|hdl-access=free}}</ref><ref name=":0" /><ref name=":6" /> Constitutive defenses are always expressed and offer immediate protection from invaders but could also be defeated by antagonists that have evolved adaptations to these defense mechanisms.<ref name=":2" /><ref name=":0" /> One of the common secondary compounds used by ''Pinaceae'' are phenolics or polyphenols. These secondary compounds are preserved in [[vacuole]]s of polyphenolic [[Parenchyma|parenchyma cells]] (PP) in the [[Phloem|secondary phloem]].<ref name=":3">{{Cite journal|last1=Nagy|first1=N. E.|last2=Krokene|first2=P.|last3=Solheim|first3=H.|date=2006-02-01|title=Anatomical-based defense responses of Scots pine (Pinus sylvestris) stems to two fungal pathogens|journal=Tree Physiology|language=en|volume=26|issue=2|pages=159–167|doi=10.1093/treephys/26.2.159|pmid=16356912|issn=0829-318X|doi-access=free}}</ref><ref name=":9" />

=== Induced defenses ===
[[Inducible plant defenses against herbivory|Induced defense]] responses need to be activated by certain cues, such as herbivore damage or other biotic signals.<ref name=":2" />

A common induced defense mechanism used by ''Pinaceae'' is resins.<ref name=":4">{{Cite journal|last1=Nagy|first1=Nina E.|last2=Franceschi|first2=Vincent R.|last3=Solheim|first3=Halvor|last4=Krekling|first4=Trygve|last5=Christiansen|first5=Erik|date=2000-03-01|title=Wound-induced traumatic resin duct development in stems of Norway spruce (Pinaceae): anatomy and cytochemical traits|journal=American Journal of Botany|language=en|volume=87|issue=3|pages=302–313|doi=10.2307/2656626|issn=1537-2197|jstor=2656626|pmid=10718991}}</ref> Resins are also one of the primary defenses used against attack.<ref name=":1" /> Resins are short term defenses that are composed of a complex combination of volatile [[Monoterpene|mono]]- (C<sub>10</sub>) and [[sesquiterpene]]s (C<sub>15</sub>) and nonvolatile [[diterpene]] resin acids (C<sub>20</sub>).<ref name=":1" /><ref name=":4" /> They are produced and stored in specialized secretory areas known as resin ducts, resin blisters, or resin cavities.<ref name=":4" /> Resins have the ability to wash away, trap, fend off antagonists, and are also involved in wound sealing.<ref name=":3" /> They are an effective defense mechanism because they have toxic and inhibitory effects on invaders, such as insects or pathogens.<ref name=":5">{{Cite journal|last1=Lewinsohn|first1=Efraim|last2=Gijzen|first2=Mark|last3=Croteau|first3=Rodney|date=1991-05-01|title=Defense Mechanisms of Conifers: Differences in Constitutive and Wound-Induced Monoterpene Biosynthesis Among Species|journal=Plant Physiology|language=en|volume=96|issue=1|pages=44–49|doi=10.1104/pp.96.1.44|issn=0032-0889|pmid=16668184|pmc=1080711}}</ref> Resins could have developed as an evolutionary defense against [[bark beetle]] attacks.<ref name=":4" /> One well researched resin present in ''Pinaceae'' is [[oleoresin]]. Oleoresin had been found to be a valuable part of the [[Pinophyta|conifer]] defense mechanism against [[Biotic stress|biotic attacks]].<ref name=":5" /> They are found in [[Plant secretory tissue|secretory tissues]] in tree stems, roots, and leaves.<ref name=":5" /> Oleoresin is also needed in order to classify conifers.<ref name=":5" />

=== Active research: methyl jasmonate ===
The topic of defense mechanisms within family ''Pinaceae'' is a very active area of study with numerous studies being conducted. Many of these studies use [[methyl jasmonate]] (MJ) as an antagonist.<ref name=":6" /><ref name=":9" /><ref name=":10">{{Cite journal|last1=Fäldt|first1=Jenny|last2=Martin|first2=Diane|last3=Miller|first3=Barbara|last4=Rawat|first4=Suman|last5=Bohlmann|first5=Jörg|date=2003-01-01|title=Traumatic resin defense in Norway spruce (Picea abies): Methyl jasmonate-induced terpene synthase gene expression, and cDNA cloning and functional characterization of (+)-3-carene synthase|journal=Plant Molecular Biology|language=en|volume=51|issue=1|pages=119–133|doi=10.1023/A:1020714403780|pmid=12602896|s2cid=21153303|issn=0167-4412}}</ref> Methyl jasmonate is known to be able to induce defense responses in the stems of multiple ''Pinaceae'' species.<ref name=":6" /><ref name=":10" /> It has been found that MJ stimulated the activation of PP cells and formation of xylem traumatic resin ducts (TD). These are structures that are involved in the release of phenolics and resins, both forms of defense mechanism.<ref name=":6" /><ref name=":9" />

<gallery>
File:Pinceae_Bishop_pine_prickle_cone_pine_pinus_muricata.jpg | Close up of bishop pine cones
File:Pinaceae_Knobcone_Pine_Pinus_attenuata.jpg | Knobcone pine cone
</gallery>

== References ==
{{Reflist}}

==External links==
{{Commons category}}
{{Wikispecies}}

* [http://www.pinetum.org/ Arboretum de Villardebelle] French Arboretum of conifers around the world 
* [http://www.conifers.org/pi/Pinaceae.php Gymnosperm Database] – Pinaceae
* [http://tolweb.org/Pinaceae/21624 Pinaceae on the web page of the Tree-of-Life project]
* [https://www.thespruce.com/pine-trees-from-around-the-world-3269718 40 Pine Trees From Around the World] by The Spruce
* {{Jepson eFlora|32|Pinaceae|link=1|type=key|mode=cs2}}, covers Californian species and much of western North America
* [http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=10691 Pinaceae in Flora of North America]
* [https://plants.usda.gov/core/profile?symbol=PINUS Pinus in USDA Plants Database]

{{Acrogymnospermae classification}}
{{Taxonbar|from=Q101680}}
{{Authority control}}
[[Category:Pinaceae| ]]
[[Category:Pinales families]]