Pinales

Template:Short description Template:Automatic taxobox

The order Pinales in the division Pinophyta, class Pinopsida, comprises all the extant conifers. The distinguishing characteristic is the reproductive structure known as a cone produced by all Pinales. All of the extant conifers, such as Araucaria, cedar, celery-pine, cypress, fir, juniper, kauri, larch, pine, redwood, spruce, and yew, are included here. Some fossil conifers, however, belong to other distinct orders within the division Pinophyta.

Multiple molecular studies indicate this order being paraphyletic with respect to Gnetales, with studies recovering Gnetales as either a sister group to Pinaceae or being more derived than Pinaceae but sister to the rest of the group.

TaxonomyEdit

HistoryEdit

Brown (1825)Template:Efn Template:Sfn 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.Template:Sfn Shortly afterwards, Brongniart (1828) coined the term Phanérogames gymnospermsTemplate:Efn to describe the former group.Template:Sfn The distinction was then formalized by Lindley (1830), dividing what he referred to as the subclass Dicotyledons into two tribes, Gymnosperms and Angiosperms.Template:Efn In the gymnosperms (or Gymnospermae) Lindley included two orders, the Cycadeae and the Coniferae.Template:Sfn Template:Sfn In his final work (1853) he described Gymnogens as a class with four orders;Template:Sfn

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;Template:Sfn

Gnetaceae
Coniferae
Cycadaceae

In the Engler system (1903) Gymnospermae is listed as a subdivision (Unterabteilung) and adopted more of a splitter approach, including extinct taxa, with the following six classes;Template:Sfn

During this period, Gorozhankin published his treatise on Gymnosperms (1895), for which he bears the botanical authority for Pinales, Gorozh.. In his classification, Gymnospermae (alternatively named Archespermae) was a class of the division Archegoniatae, divided into subclasses;Template:Sfn

Cycadoideae
Peucideae (Coniferae)

A system of two groups was maintained by the most commonly used classification in the twentieth century,Template:Sfn the revision of the Engler system by Pilger (1926), who grouped 12 families of the Gymnospermae subdivision into 2 classes;Template:Sfn

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),Template:Sfn Benson (1957)Template:Sfn and Cronquist (1960).Template:Sfn

In the latter, Cronquist divided Gymnospermae into two divisions;

division Coniferophyta
- class Coniferae
- class Chlamydospermae (Gnetales)
division Cycadophyta
- class Cycadae

Benson,(1957)Template:Sfn who introduced the term Pinales, divided gymnosperms into four classes;Template:Sfn

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;Template:Sfn Template:Sfn

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;Template:Sfn

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 Chase and Reveal (2009). In this system, the land plants form a class, Equisetopsida s.l. (sensu lato) or sensu Chase & Reveal,Template:Efn also known as embryophytes or Embryophyceae nom. illeg..Template:Sfn 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);Template:Sfn

subclass Cycadidae Pax (1)
subclass Ginkgooidae Engl. (1)
subclass Gnetidae Pax (3)
subclass Pinidae Cronquist, Takht. & Zimmerm. (conifers) (1)

ControversiesEdit

Gymnosperm (Acrogymnospermae) taxonomy has been considered controversial, and lacks consensus.Template:Sfn Template:Sfn Template:Sfn As taxonomic classification transformed from being based solely on plant morphology to molecular phylogenetics, the number of taxonomic publications increased considerably after 2008,Template:Sfn Template:Sfn Template:Sfn Template:Sfn Template:Sfn however, these approaches have not been uniform. A taxonomic classification has been complicated by the relationship of extant to extinct taxa, and within extinct taxa, and particularly the placement of Gnetophyta. The latter have been variously classified as basal to all gymnosperms, sister group to conifers (‘gnetifer’ hypothesis) or sister to Pinaceae (‘gnepine’ hypothesis) in which they are classified within the conifers.Template:Sfn The extant conifers most likely form a monophyletic group.Template:Sfn Template:Sfn 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.Template:Sfn

PhylogenyEdit

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 (angiosperms or flowering plants).

There are about 1000 extant gymnosperm species, distributed over about 12 families and 83 genera. Many of these genera are monotypic (41%), and another 27% are oligotypic (2–5 species).Template:Sfn The four subclasses have also been treated as divisions of the Spermatophytes. Alternative names and the approximate number of genera and species in each are;Template:Sfn

Cycadidae (Cycadophyta, cycads 10, 300)
Ginkgoidae (Ginkgophyta, ginkgo 1, 1)
Gnetidae (Gnetophyta 3, 100)
Pinidae (Pinophyta,Template:Sfn Template:Sfn conifers 70, 600)

The term Pinophyta has also been used to include all conifers, extinct and extant, with Pinales representing all the extant conifers.Template:Sfn

Christenhusz and colleagues extended the system of Chase and RevealTemplate:Sfn to provide a revised classification of gymnosperms in 2011, based on the above four subclades.Template:Sfn In this scheme, the Pinidae comprise three orders, including Pinales, and 6 families;

Pinales Gorozh. (Pinaceae)
Araucariales Gorozh. (Araucariaceae, Podocarpaceae)
Cupressales Link (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).Template:Sfn 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).Template:Sfn 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.Template:Sfn These relationships are shown in this cladogram, although no formal taxonomic revision was undertaken.Template:Sfn Template:Cladogram

A more comprehensive analysis was undertaken by Ran and colleagues in 2018, as part of a detailed phylogeny of all seed plants.Template:Sfn This forms the basis of the Tracheophyte Phylogeny PosterTemplate:Sfn and the Angiosperm Phylogeny Website.Template:Sfn

SubdivisionEdit

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 Pilger (1926), considered the standard through most of the twentieth century.Template:Sfn These families were treated as a single order, in distinction to some earlier systems.Template:Sfn His families were;Template:Sfn

Araucariaceae
Cupressaceae (cypresses, juniper, redwood)
Pinaceae (firs, pines, 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).Template:Sfn 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).Template:Sfn

Christenhusz and colleagues (2011) included only one family in Pinales, Pinaceae,Template:Sfn a practice subsequently followed by the Angiosperm Phylogeny Website Template:Sfn and the Gymnosperm Database.Template:Sfn 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.Template:Sfn