Pinales

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 cedar, celery-pine, cypress, fir, juniper, larch, pine, redwood, spruce, and yew, are included here. Some fossil conifers, however, belong to other distinct orders within the division Pinophyta.

Pinales
Pinchot Trail (6) (8413101824).jpg
Scientific classification e
Kingdom: Plantae
Clade: Tracheophytes
Division: Pinophyta
Class: Pinopsida
Order: Pinales
Gorozh.[1]
Families

(approximate number of species in parentheses)

Synonyms

TaxonomyEdit

Gymnosperm (Gymnospermae) taxonomy has been considered controversial, and lacks consensus.[4][2] As taxonomic classification transformed from being based solely on plant morphology to molecular phylogenetics, the number of taxonomic publications increased considerably after 2008,[5][6][1][7][8] 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.[9] While the extant gymnosperms form a monophyletic group,[3] a formal name has not been assigned to this clade.[1]

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.[10]

PhylogenyEdit

Gymnosperms are in a sister group relation to the Angiosperms (flowering plants) within the Spermatophytes (seed bearing plants), comprising four of the five major lineages of the latter. 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).[11]

These four divisions of the Spermatophytes, with the approximate number of genera and species, are;[11]

in which the Pinophyta include all conifers, extinct and extant, with Pinales representing all extant conifers.[12]

Christenhusz and colleagues proposed a revised classification of gymnosperms in 2011, in which the above four subclades are treated as subclasses of class Equisetopsida s.l. sensu lato (sensu Chase & Reveal),[b] (also known as Embryophyceae nom. illeg.[13]) which encompasses all land plants, as opposed to green algae, following their previous practice.[13][1]

The system of Christenhusz et al, treats class Equisetopsida s.l. as having fourteen four subclasses, of which these four form the clade of gymnosperms;[1]

In this scheme, the Pinidae comprise three orders, including Pinales;

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).[11] 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 confirming the ‘gnepine’ hypothesis, as shown in this cladogram.[14]

Phylogeny of Gymnosperms[14]
Gymnosperms

Cycads

Ginkgoaceae

Pinaceae

Gnetales

Sciadopityaceae

Araucariaceae

Podocarpaceae

Taxaceae (including Cephalotaxaceae)

Cupressaceae s.l.

SubdivisionEdit

Historically conifers, in the order Pinales has been considered to consist of with six to seven extant families, based on the classification of class Coniferae by Pilger (1926);[15]

Subsequent revisions merged the Taxodiaceae and Cupressaceae, and placed Sciadopitys, formerly in Cupressaceae, into a separate family (Sciadopityaceae).[16] 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).[11]

Christenhusz and colleagues (2011) included only one family in Pinales, Pinaceae,[1] a practice subsequently followed by the Angiosperm Phylogeny Website[17] and the Gymnosperm Database.[16] 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.[1]

NotesEdit

  1. ^ Taxon names beginning with the root conifer- are considered illegitimate because they are not based on an underlying genus[1]
  2. ^ This term should not be confused with Equisetopsida sensu stricto when used as a class of ferns, synonymous with Equisetidae

ReferencesEdit

BibliographyEdit

BooksEdit

EncyclopaediasEdit

ArticlesEdit

WebsitesEdit

External linksEdit

  •   Media related to Pinales at Wikimedia Commons
  •   Data related to Pinales at Wikispecies