Pinales

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Pinales
Pinus sylvestris, scots pine tree
Pinus sylvestris
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Gymnospermae
Division: Pinophyta
Class: Pinopsida
Subclass: Pinidae
Order: Pinales
Gorozh.[1][2]
Type genus
Pinus
Families

(approximate number of species in parentheses)

Synonyms

The

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.

Taxonomy

History

Dicotyledons into two tribes, Gymnosperms and Angiosperms.[d] In the gymnosperms (or Gymnospermae) Lindley included two orders, the Cycadeae and the Coniferae.[8][9] In his final work (1853) he described Gymnogens as a class with four orders;[10]

  • 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;[11]

  • 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;[12]

During this period,

botanical authority for Pinales, Gorozh.. In his classification, Gymnospermae (alternatively named Archespermae) was a class of the division Archegoniatae, divided into subclasses;[1]

  • Cycadoideae
  • Peucideae
    (Coniferae)

A system of two groups was maintained by the most commonly used classification in the twentieth century,[13] the revision of the Engler system by Pilger (1926), who grouped 12 families of the Gymnospermae subdivision into 2 classes;[14]

  • 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),[15] Benson (1957)[16] and Cronquist (1960).[17]

In the latter, Cronquist divided Gymnospermae into two divisions;

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

Benson,(1957)[16] who introduced the term Pinales, divided gymnosperms into four classes;[9]

  • 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;[18][9]

  • 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;[9]

  • Cycadopsida
    • order Cycadales
  • Coniferopsida
    • subclass Multinervidae (6 orders)
    • subclass Taxidae
      • order Taxales
      • order Pinales

With the development of the

angiosperms). The gymnosperms are represented by four of these subclasses, placing them in a sister group relationship to angiosperms. Subclasses (number of orders);[19]

Controversies

monophyletic group.[4][2] 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.[21]

Phylogeny

Gymnosperms form a group of four subclasses among the

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

divisions of the Spermatophytes. Alternative names and the approximate number of genera and species in each are;[27]

  • Cycadidae (Cycadophyta, cycads 10, 300)
  • Ginkgoidae (Ginkgophyta, ginkgo 1, 1)
  • Gnetidae (Gnetophyta 3, 100)
  • Pinidae (Pinophyta,[18][28] conifers 70, 600)

The term Pinophyta has also been used to include all conifers, extinct and extant, with Pinales representing all the extant conifers.[29]

subclades.[2]
In this scheme, the Pinidae comprise three orders, including Pinales, and 6 families;

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).[27] 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).[30] 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.[31] These relationships are shown in this cladogram, although no formal taxonomic revision was undertaken.[31]

Phylogeny of Gymnosperms, subclasses, orders, families[31][2]
Gymnosperms

Cycadidae (Cycadales)

Ginkgoidae (Ginkgoales)

Pinidae (Pinales)

Gnetidae

Sciadopityaceae

Araucariales
Cupressales

Taxaceae (including Cephalotaxaceae)

Cupressaceae s.l.

A more comprehensive analysis was undertaken by Ran and colleagues in 2018, as part of a detailed phylogeny of all seed plants.[32] This forms the basis of the Tracheophyte Phylogeny Poster[30] and the Angiosperm Phylogeny Website.[33]

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

Pilger (1926), considered the standard through most of the twentieth century.[13] These families were treated as a single order, in distinction to some earlier systems.[34] His families were;[14]

Subsequent revisions merged the Taxodiaceae and Cupressaceae, and placed

Phyllocladaceae were included in Podocarpaceae. Yews (Taxaceae) have sometimes been treated as a separate order (Taxales).[27]

Christenhusz and colleagues (2011) included only one family in Pinales, Pinaceae,[2] a practice subsequently followed by the Angiosperm Phylogeny Website[33] and the Gymnosperm Database.[35] 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.[2]

Notes

  1. ^ Taxon names beginning with the root conifer- are considered illegitimate because they are not based on an underlying genus[2]
  2. Linnean Society
    in 1825, published in 1826
  3. ^ Phanerogam, or seed plant, indicating visible sexual organs, and gymnosperm indicating exposed seeds
  4. ^ Angiosperm indicating enclosed seeds
  5. Equisetopsida
    sensu stricto when used as a class of ferns, synonymous with Equisetidae

References

Bibliography

Books

Encyclopaedias

Articles

Websites

External links

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