Editing Pinales (section)

== Taxonomy ==

=== History ===

[[Robert Brown (botanist, born 1773)|Brown]] (1825){{efn|Read before the [[Linnean Society]] in 1825, published in 1826}}{{sfn|Brown|1826}} first discerned that there were two groups of seed plants, distinguished by the form of seed development, based on whether the [[ovules]] were exposed, receiving pollen directly, or enclosed, which do not.{{sfn|Tomlinson|2012}} Shortly afterwards, [[Adolphe-Théodore Brongniart|Brongniart]] (1828) coined the term ''[[Phanérogames]] gymnosperms''{{efn|''Phanerogam'', or seed plant, indicating visible sexual organs, and ''gymnosperm'' indicating exposed seeds}} to describe the former group.{{sfn|Brongniart|1828–1837}} The distinction was then formalized by [[John Lindley|Lindley]] (1830), dividing what he referred to as the subclass [[Dicotyledons]] into two [[Tribe (biology)|tribes]], Gymnosperms and Angiosperms.{{efn|''Angiosperm'' indicating enclosed seeds}} In the gymnosperms (or Gymnospermae) Lindley included two orders, the Cycadeae and the Coniferae.{{sfn|Lindley|1830}}{{sfn|De-Zhi et al|2004}} In his final work (1853) he described Gymnogens as a class with four orders;{{sfn|Lindley|1853}}
* Cycadeaceae (cycads)
* Pinaceae (conifers)
* Taxaceae (taxads)
* Gnetaceae

In contrast, [[Bentham and Hooker]] (1880) included only three orders in the class Gymnospermeae, by including taxads within Coniferae;{{sfn|Bentham|Hooker|1862–1883}}
* Gnetaceae
* Coniferae
* Cycadaceae

In the [[Engler system]] (1903) Gymnospermae is listed as a subdivision (''Unterabteilung'') and adopted more of a [[Lumpers and splitters|splitter]] approach, including extinct taxa, with the following six classes;{{sfn|Engler|1903}}
* [[Cycadales]]
* [[Bennettitales]]
* [[Cordaitales]]
* [[Ginkgoales]]
* Coniferae
* [[Gnetales]]

During this period, [[Ivan Nikolaevich Gorozhankin|Gorozhankin]] published his treatise on Gymnosperms (1895), for which he bears the [[botanical authority]] for Pinales, <small>Gorozh.</small>. In his classification, Gymnospermae (alternatively named Archespermae) was a class of the division [[Archegoniatae]], divided into subclasses;{{sfn|Gorozhankin|1904}}
* [[Cycadoideae]]
* [[Peucideae]] (Coniferae)

A system of two groups was maintained by the most commonly used classification in the twentieth century,{{sfn|Brunsfield et al|1994}} the revision of the Engler system by Pilger (1926), who grouped 12 families of the Gymnospermae subdivision into 2 classes;{{sfn|Pilger|1926}}
* Coniferales (Coniferae)
* Gnetales

The treatment of Gymnosperms as two groups, though with varying composition and names, was followed for most of the twentieth century, including the systems of Chamberlain (1935),{{sfn|Chamberlain|1935}} Benson (1957){{sfn|Benson|1957}} and [[Cronquist system|Cronquist]] (1960).{{sfn|Cronquist|1960}}

In the latter, Cronquist divided Gymnospermae into two divisions; 
* division Coniferophyta 
** class Coniferae
** class [[Chlamydospermae]] (Gnetales)
* division Cycadophyta
** class Cycadae

Benson,(1957){{sfn|Benson|1957}} who introduced the term '''Pinales''', divided gymnosperms into four classes;{{sfn|De-Zhi et al|2004}}

* Conopsida (conifers, including Pinales)
* [[Ephedropsida]]
* [[Gnetopsida]]
* [[Cycadopsida]]

In a later revision, in collaboration with two other taxonomists (1966), Cronquist merged all the gymnosperms into a single division, '''Pinophyta''', with three subdivisions reflecting the main lineages;{{sfn|Cronquist et al|1966}}{{sfn|De-Zhi et al|2004}}
* Cycadicae
* Pinicae
* Gneticae

In the era of [[molecular phylogenetics]], De-Zhi and colleagues (2004) once again proposed a division of 12 gymnosperm families into two classes;{{sfn|De-Zhi et al|2004}}
* Cycadopsida
** order Cycadales
* Coniferopsida
** subclass Multinervidae (6 orders)
** subclass Taxidae
*** order Taxales
*** order Pinales

With the development of the [[Angiosperm Phylogeny Group]] came a major realignment of the linear classification of the [[land plants]], by [[Mark Chase|Chase]] and [[James L. Reveal|Reveal]] (2009). In this system, the land plants form a class, [[Equisetopsida sensu lato|Equisetopsida ''s.l.'' (''sensu lato'')]] or ''[[sensu]]'' [[Mark Chase|Chase]] & [[James L. Reveal|Reveal]],{{efn|This term should not be confused with [[Equisetopsida]] ''sensu stricto'' when used as a class of ferns, synonymous with Equisetidae}} also known as embryophytes or Embryophyceae ''[[nom. illeg.]]''.{{sfn|Chase|Reveal|2009}} Class Equisetopsida ''s.l.'' is divided into 14 [[subclades]] as subclasses, including Magnoliidae ([[angiosperms]]). The gymnosperms are represented by four of these subclasses, placing them in a [[sister group]] relationship to angiosperms. Subclasses (number of orders);{{sfn|Chase|Reveal|2009}}
* subclass Cycadidae <small>[[Ferdinand Pax|Pax]]</small> (1)
* subclass Ginkgooidae <small>[[Adolf Engler|Engl.]]</small> (1)
* subclass Gnetidae <small>Pax</small> (3)
* subclass Pinidae <small>[[Arthur Cronquist|Cronquist]], [[Takht.]] & [[Zimmerm.]]</small> (conifers) (1)

=== Controversies ===

[[Gymnosperm]] (Acrogymnospermae) [[Taxonomy (biology)|taxonomy]] has been considered controversial, and lacks consensus.{{sfn|Farjon|2001}}{{sfn|Eckenwalder|2008}}{{sfn|Nagalingum|Burleigh|2018}} As [[taxonomic classification]] transformed from being based solely on [[plant morphology]] to [[molecular phylogenetics]], the number of taxonomic publications increased considerably after 2008,{{sfn|Eckenwalder|2009}}{{sfn|Farjon|2010}}{{sfn|Christenhusz et al|2011}}{{sfn|Debreczy|Rácz|2011}}{{sfn|Farjon|Filer|2013}} however, these approaches have not been uniform. A taxonomic classification has been complicated by the relationship of [[Extant taxon|extant]] to extinct [[taxa]], and within extinct taxa, and particularly the placement of [[Gnetophyta]]. The latter have been variously classified as [[basal group|basal]] to all gymnosperms, [[sister group]] to conifers (‘gnetifer’ hypothesis) or sister to Pinaceae (‘gnepine’ hypothesis) in which they are classified within the conifers.{{sfn|Farjon|2018}} The extant conifers most likely form a [[monophyletic]] group.{{sfn|Gernandt et al|2011}}{{sfn|Christenhusz et al|2011}} In 2018, the Gymnosperm Phylogeny Group was established, analogous to the [[Angiosperm Phylogeny Group]] and [[Pteridophyte Phylogeny Group]], with the intention of reaching a consensus.{{sfn|Nagalingum|Burleigh|2018}}

=== Phylogeny ===

Gymnosperms form a group of four subclasses among the [[spermatophytes]] (seed bearing plants). In turn, the seed plants together with the [[monilophyte]] [[fern]] subclasses make up the [[tracheophytes]] (vascular plants), part of the class [[Equisetopsida]] (embryophytes or land plants), as opposed to the [[green algae]]. Among the seed plants, the gymnosperms are a sister group to the subclass [[Magnoliidae sensu Chase & Reveal|Magnoliidae]] (angiosperms or flowering plants).

There are about 1000 extant gymnosperm [[species]], distributed over about 12 [[Families (biology)|families]] and 83 [[genera]]. Many of these genera are [[monotypic]] (41%), and another 27% are oligotypic (2–5 species).{{sfn|Wang|Ran|2014}} The four subclasses have also been treated as [[division (botany)|divisions]] of the Spermatophytes. Alternative names and the approximate number of genera and species in each are;{{sfn|Wang|Ran|2014}}
* [[Cycadidae]] (Cycadophyta, cycads 10, 300)
* [[Ginkgoidae]] (Ginkgophyta, ginkgo 1, 1)
* Gnetidae (Gnetophyta 3, 100)
* Pinidae (Pinophyta,{{sfn|Cronquist et al|1966}}{{sfn|Reveal|1995}} conifers 70, 600)

The term Pinophyta has also been used to include all conifers, extinct and extant, with Pinales representing all the extant conifers.{{sfn|Delevoryas|2015}}
 
[[Christenhusz]] and colleagues extended the system of Chase and Reveal{{sfn|Chase|Reveal|2009}} to provide a revised classification of gymnosperms in 2011, based on the above four [[subclades]].{{sfn|Christenhusz et al|2011}} In this scheme, the Pinidae comprise three orders, including Pinales, and 6 families;
* Pinales <small>[[Gorozh.]]</small> ([[Pinaceae]]) 
* [[Araucariales]] <small>Gorozh.</small> ([[Araucariaceae]], [[Podocarpaceae]])
* [[Cupressales]] <small>[[Johann Heinrich Friedrich Link|Link]]</small> ([[Sciadopityaceae]], [[Cupressaceae]], [[Taxaceae]])

However, the exact phylogeny remained a topic that was 'hotly debated", in particular whether the main lineages were best represented by the four subclasses of Christenhusz and colleagues or the more traditional five clades (cycads, ginkgos, cupressophytes, Pinaceae and gnetophytes).{{sfn|Wang|Ran|2014}} In 2014 the first complete molecular phylogeny was published, based on 90 species representing all extant genera. This established cycads as the basal group, followed by Ginkgoaceae, as sister to the remaining gymnosperms, and supporting the ‘gnepine’ hypothesis. This analysis favours the five clade hypothesis, the remaining clade following divergence of the Pinidae, are referred to as the conifer II clade, or cupressophytes, in distinction from the conifer I clade (Gnetidae, Pinidae).{{sfn|Cole|Bachelier|2019}} This clade, in turn, has two lineages. The first consisting of Sciadopityaceae and the Araucariales, the second being the Cupressales. In the Christenhusz scheme, the Sciadopityaceae were considered to be within Cupressales. The term Cupressaceae ''s.l.'' refers to the inclusion of Taxodiaceae.{{sfn|Lu et al|2014}} These relationships are shown in this [[cladogram]], although no formal taxonomic revision was undertaken.{{sfn|Lu et al|2014}} 
{{cladogram|title=Phylogeny of Gymnosperms, subclasses, orders, families{{sfn|Lu et al|2014}}{{sfn|Christenhusz et al|2011}} 
|align=left
|cladogram=
{{clade|style=font-size:90%;line-height:100%
|label1='''Gymnosperms'''
|1={{clade
    |label1=
    |1=[[Cycadidae]] (Cycadales)
    |label2= 
    |2={{clade 
      |1={{clade
        |1={{clade
          |1={{clade
             |1= [[Ginkgoidae]] (Ginkgoales)
             }}
         |2={{clade
          |1={{clade
           |1=[[Pinidae]] (Pinales)
           |2={{clade
             |1={{clade
                |1=[[Gnetidae]]
                }}
             |2={{clade
                  |1=[[Sciadopityaceae]]
                  |2={{clade
                  |label1=[[Araucariales]]
                  |label2=[[Cupressales]]
                     |1={{clade
                        |1=[[Araucariaceae]]
                        |2=[[Podocarpaceae]]
                        }}
                     |2={{clade
                        |1=[[Taxaceae]] (including Cephalotaxaceae)
                        |2= [[Cupressaceae]] ''s.l.''
                     }}
                     }}
                
                }}
           }}
}}
}}
}}
}} 
}}
}}
}}
}}
{{clear}}

A more comprehensive analysis was undertaken by Ran and colleagues in 2018, as part of a detailed phylogeny of all seed plants.{{sfn|Ran et al|2018}} This forms the basis of the Tracheophyte Phylogeny Poster{{sfn|Cole|Bachelier|2019}} and the Angiosperm Phylogeny Website.{{sfn|Stevens|2020}}

=== Subdivision ===

Historically conifers, in the order Pinales have been considered to consist of six to seven extant families, based on the classification of class Coniferae by [[Robert Pilger|Pilger]] (1926), considered the standard through most of the twentieth century.{{sfn|Brunsfield et al|1994}} These families were treated as a single order, in distinction to some earlier systems.{{sfn|Davy|1937}} His families were;{{sfn|Pilger|1926}} 
* [[Araucariaceae]]
* [[Cupressaceae]] ([[cypresses]], [[juniper]], [[redwood]])
* [[Pinaceae]] ([[firs]], [[pines]], [[Cedar (plant)|cedars]], [[larch]], [[spruce]])
* [[Podocarpaceae]]
* [[Taxaceae]] ([[yews]]) 
* [[Cephalotaxaceae]]
* [[Taxodiaceae]]

Subsequent revisions merged the Taxodiaceae and Cupressaceae, and placed ''[[Sciadopitys]]'', formerly in Cupressaceae, into a separate family (Sciadopityaceae).{{sfn|Earle|2020}} Cephalotaxaceae had previously been recognized as a separate family, but was subsequently included in Taxaceae. Similarly [[Phyllocladaceae]] were included in Podocarpaceae. Yews (Taxaceae) have sometimes been treated as a separate order (Taxales).{{sfn|Wang|Ran|2014}}

Christenhusz and colleagues (2011) included only one family in Pinales, Pinaceae,{{sfn|Christenhusz et al|2011}} a practice subsequently followed by the [[Angiosperm Phylogeny Website]]{{sfn|Stevens|2020}} and the Gymnosperm Database.{{sfn|Earle|2020}} In this restricted model Pinales (Pinaceae) comprisea 11 genera and about 225 species, all of the other conifers originally included in this order, being included in other orders such as Cupressales.{{sfn|Christenhusz et al|2011}}