Editing Conifer (section)

== Taxonomy and evolution ==
Conifers are by far the largest and most economically important group of gymnosperms. The division Pinophyta consists of just one class, Pinopsida, which includes both living and fossil taxa. Subdivision of the living conifers into two or more orders has been proposed from time to time. The most commonly seen in the past was a split into two orders, [[Taxales]] (Taxaceae only) and [[Pinales]] (the rest), but recent research into [[molecular biology|DNA sequences]] suggests that this interpretation leaves the Pinales without Taxales as [[paraphyletic]], and the latter order is no longer considered distinct. A more accurate subdivision would be to split the class into three orders, Pinales containing only Pinaceae, Araucariales containing Araucariaceae and Podocarpaceae, and Cupressales containing the remaining families (including Taxaceae), but there has not been any significant support for such a split, with the majority of opinion preferring retention of all the families within a single order Pinales, despite their antiquity and diverse [[morphology (biology)|morphology]].

There were seven families of conifers {{Circa|2011}},<ref name="GymnoData">{{cite web|url=http://www.conifers.org/zz/pinales.htm|title=Pinidae (conifers) description – The Gymnosperm Database|url-status=dead|archive-url=https://web.archive.org/web/20160220110331/http://www.conifers.org/zz/pinales.htm|archive-date=2016-02-20}}</ref> with 65–70 genera and over 600 living species ({{Circa|2002|lk=no}}).<ref name="Judd-2002">{{cite book |last1=Judd |first1=W.S |title=Plant systematics, a phylogenetic approach |last2=Campbell |first2=C.S. |last3=Kellogg |first3=E.A. |last4=Stevens |first4=P.F. |last5=Donoghue |first5=M.J. |date=2002 |publisher=Sinauer Associates |isbn=0-87893-403-0 |edition=2nd |location=Sunderland, Massachusetts}}</ref>{{rp|205}}<ref>{{cite journal |last1=Lott |first1=John N.A. |last2=Liu |first2=Jessica C. |last3=Pennell |first3=Kelly A |last4=Lesage |first4=Aude |last5=West |first5=M Marcia |year=2002 |title=Iron-rich particles and globoids in embryos of seeds from phyla Coniferophyta, Cycadophyta, Gnetophyta, and Ginkgophyta: characteristics of early seed plants |journal=Canadian Journal of Botany |volume=80 |issue=9 |pages=954–961 |doi=10.1139/b02-083 |bibcode=2002CaJB...80..954L }}</ref>{{Update inline|date=December 2023|reason=The taxobox shows six conifer families and probably reflects a more recent taxonomy (where gnetophytes are included within Pinophyta and ''Cephalotaxus'' is included in Taxaceae).}} The seven most distinct families are linked in the box above right and phylogenetic diagram left. In other interpretations, the [[Cephalotaxaceae]] may be better included within the Taxaceae, and some authors additionally recognize [[Phyllocladus|Phyllocladaceae]] as distinct from Podocarpaceae (in which it is included here). The family [[Taxodiaceae]] is here included in the family Cupressaceae, but was widely recognized in the past and can still be found in many field guides. A new classification and linear sequence based on molecular data can be found in an article by Christenhusz et&nbsp;al.<ref name="Christenhusz-2011">{{cite journal |last1=Christenhusz |first1=M.J.M. |last2=Reveal |first2=J. |last3=Farjon |first3=A.|last4=Gardner.|first4=M.F. |last5=Mill |first5=R.R. |last6=Chase |first6=M.W. |year=2011|title=A new classification and linear sequence of extant gymnosperms |journal=Phytotaxa |volume=19 |issue=1 |pages=55–70 |doi=10.11646/phytotaxa.19.1.3 |bibcode=2011Phytx..19...55C }}</ref>

The conifers are an ancient group, with a [[fossil]] record extending back about 300&nbsp;million years to the [[Paleozoic]] in the late [[Carboniferous]] period; even many of the modern genera are recognizable from fossils 60–120&nbsp;million years old. Other classes and orders, now long extinct, also occur as fossils, particularly from the late Paleozoic and [[Mesozoic]] eras. Fossil conifers included many diverse forms, the most dramatically distinct from modern conifers being some [[herb]]aceous conifers with no woody stems.<ref>{{cite journal |last1=Rothwell |first1=Gar W. |last2=Grauvogel-Stamm |first2=Léa |last3=Mapes |first3=Gene |title=An herbaceous fossil conifer: Gymnospermous ruderals in the evolution of Mesozoic vegetation |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |date=February 2000 |volume=156 |issue=1–2 |pages=139–145 |doi=10.1016/S0031-0182(99)00136-4 |bibcode=2000PPP...156..139R }}</ref> Major fossil orders of conifers or conifer-like plants include the [[Cordaitales]], [[Voltziales]] and perhaps also the [[Czekanowskiales]] (possibly more closely related to the [[Ginkgo]]phyta). The cladogram summarizes conifer phylogeny:<ref>Derived from papers by A. Farjon and C. J. Quinn & R. A. Price in the Proceedings of the Fourth International Conifer Conference, ''Acta Horticulturae'' 615 (2003)</ref>

{{clade|style=line-height:100%;
|1={{clade
   |1=[[Pinaceae]]
   |2={{clade
      |1={{clade
         |1=[[Araucariaceae]]
         |2=[[Podocarpaceae]]
         }}
      |2={{clade
         |1=[[Sciadopityaceae]]
         |2={{clade
            |1=[[Cupressaceae]]
            |2={{clade
               |1=[[Cephalotaxaceae]]
               |2=[[Taxaceae]]
               }}
            }}
         }}
      }}
   }}
}}

Multiple studies indicate that the [[Gnetophyta]] belong within the conifers despite their distinct appearances, either placing them as a [[sister group]] to [[Pinales]] (the 'gnepine' hypothesis) or as being more derived than Pinales but sister to the rest of the group. Most recent studies favor 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 |last12=Smith |first12=Stephen A. |last13=Yi |first13=Ting-Shuang |title=Gene duplications and phylogenomic conflict underlie major pulses of phenotypic evolution in gymnosperms |journal=Nature Plants |date=19 July 2021 |volume=7 |issue=8 |pages=1015–1025 |doi=10.1038/s41477-021-00964-4 |pmid=34282286 |bibcode=2021NatPl...7.1015S }}</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 |date=27 June 2018 |volume=285 |issue=1881 |pages=20181012 |doi=10.1098/rspb.2018.1012 |pmc=6030518 |pmid=29925623}}</ref><ref>{{cite journal |last1=Farjon |first1=Aljos |title=The Kew Review: Conifers of the World |journal=Kew Bulletin |date=April 2018 |volume=73 |issue=1 |page=8 |doi=10.1007/s12225-018-9738-5 |bibcode=2018KewBu..73....8F |doi-access=free}}
</ref>

[[File:Abies lasiocarpa 5922.JPG|thumb|upright|The narrow conical shape of northern conifers, and their downward-drooping limbs, help them shed snow.]]

=== Fossil history ===

The earliest conifers appear in the fossil record during the Late [[Carboniferous]] ([[Pennsylvanian (geology)|Pennsylvanian]]), over 300 million years ago. Conifers are thought to be most closely related to the [[Cordaitales]]'','' a group of extinct Carboniferous-Permian trees and clambering plants whose reproductive structures had some similarities to those of conifers. The most primitive conifers belong to the paraphyletic assemblage of "[[Walchia|walchian conifers]]", which were small trees, and probably originated in dry upland habitats. The range of conifers expanded during the Early [[Permian]] ([[Cisuralian]]) to lowlands due to increasing aridity. Walchian conifers were gradually replaced by more advanced [[Voltziales|voltzialean]] or "transition" conifers.<ref name="Feng-2017">{{Cite journal |last=Feng |first=Zhuo |date=September 2017 |title=Late Palaeozoic plants |journal=Current Biology |volume=27 |issue=17 |pages=R905–R909 |bibcode=2017CBio...27.R905F |doi=10.1016/j.cub.2017.07.041 |pmid=28898663 |doi-access=free}}</ref> Conifers were largely unaffected by the [[Permian–Triassic extinction event]],<ref>{{Cite journal |last1=Nowak |first1=Hendrik |last2=Schneebeli-Hermann |first2=Elke |last3=Kustatscher |first3=Evelyn |date=2019-01-23 |title=No mass extinction for land plants at the Permian–Triassic transition |journal=Nature Communications |language=en |volume=10 |issue=1 |pages=384 |bibcode=2019NatCo..10..384N |doi=10.1038/s41467-018-07945-w |pmc=6344494 |pmid=30674875 |doi-access=free}}</ref> and were dominant land plants of the [[Mesozoic]] era. Modern groups of conifers emerged from the Voltziales during the Late Permian through [[Jurassic]].<ref name="Leslie-2018">{{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=September 2018 |title=An overview of extant conifer evolution from the perspective of the fossil record |journal=American Journal of Botany |language=en |volume=105 |issue=9 |pages=1531–1544 |doi=10.1002/ajb2.1143 |pmid=30157290 |doi-access=free}}</ref> Conifers underwent a major decline in the [[Late Cretaceous]] corresponding to the explosive [[adaptive radiation]] of [[flowering plant]]s.<ref>{{cite journal |last1=Condamine |first1=Fabien L. |last2=Silvestro |first2=Daniele |last3=Koppelhus |first3=Eva B. |last4=Antonelli |first4=Alexandre |title=The rise of angiosperms pushed conifers to decline during global cooling |journal=Proceedings of the National Academy of Sciences |date=17 November 2020 |volume=117 |issue=46 |pages=28867–28875 |doi=10.1073/pnas.2005571117 |bibcode=2020PNAS..11728867C |pmc=7682372 |pmid=33139543 |doi-access=free }}</ref>