View source for Biology:Seed plant

{{short description|Clade of seed plants}}
{{Automatic taxobox
| name              = Seed plants
| fossil_range      = {{fossilrange|Famennian|Present}}
| image             = PinusSylvestris.jpg
| image_upright     = 0.5
| image_caption     = Scots pine, ''[[Biology:Pinus sylvestris|Pinus sylvestris]]'', a member of the [[Biology:Pinophyta|Pinophyta]]
| image2            = Acer pseudoplatanus Chaltenbrunnen.jpg
| image2_upright    = 1.0
| image2_caption    = Sycamore maple, ''Acer pseudoplatanus'', a member of the [[Biology:Eudicots|Eudicots]]
| taxon             = Spermatophytes/Plantae
| authority         =
| subdivision_ranks = Extant divisions
| subdivision       = *[[Biology:Gymnosperm|Gymnosperm]]ae
** [[Biology:Cycadophyta|Cycadophyta]]
** [[Biology:Ginkgophyta|Ginkgophyta]]
** [[Biology:Pinophyta|Pinophyta]]
** [[Biology:Gnetophyta|Gnetophyta]]
* [[Biology:Flowering plant|Angiospermae]]
| synonyms = *Phanerogamae
* Phaenogamae
}}

A '''seed plant''' or '''spermatophyte''' ({{lit|seed plant}}; {{etymology|grc|''{{wikt-lang|grc|σπέρματος}}'' ({{grc-transl|σπέρματος}})|seed||''{{wikt-lang|grc|φυτόν}}'' (phytón)|plant}}), also known as a '''phanerogam''' (taxon '''Phanerogamae''') or a '''phaenogam''' (taxon '''Phaenogamae'''), is any [[Biology:Plant|plant]] that produces [[Biology:Seed|seed]]s. It is a category of [[Biology:Embryophyte|embryophyte]] (i.e. land plant) that includes most of the familiar land plants, including the flowering plants and the gymnosperms, but not ferns, mosses, or [[Biology:Algae|algae]].

The term ''phanerogam'' or ''phanerogamae'' is derived from the [[Social:Ancient Greek|Greek]] {{lang|grc|φανερός}} ({{transl|grc|phanerós}}), meaning "visible", in contrast to the term "cryptogam" or "[[Biology:Cryptogamae|cryptogamae]]" ({{etymology|grc|''κρυπτός'' (kruptós)|hidden}}), together with the [[Social:Suffix|suffix]] {{lang|grc|γαμέω}} ({{transl|grc|gaméō}}), meaning "to marry". These terms distinguish those plants with hidden sexual organs (cryptogamae) from those with visible ones (phanerogamae).

==Description==

The extant spermatophytes form five divisions, the first four of which are classified as [[Biology:Gymnosperm|gymnosperm]]s, plants that have unenclosed, "naked seeds":<ref name=Judd>{{cite book |first1=Walter S. |last1=Judd |first2=Christopher S. |last2=Campbell |first3=Elizabeth A. |last3=Kellogg |first4=Peter F. |last4=Stevens |first5=Michael J. |last5=Donoghue |title=Plant systematics, a phylogenetic approach |edition=2 |date=2002 |publisher=Sinauer Associates |location=Sunderland, Massachusetts |isbn=0-87893-403-0 }}</ref>{{rp|172}}
* [[Biology:Cycadophyta|Cycadophyta]], the cycads, a subtropical and tropical group of plants,
* [[Biology:Ginkgophyta|Ginkgophyta]], which includes a single living species of tree in the genus ''[[Biology:Ginkgo|Ginkgo]]'',
* [[Biology:Pinophyta|Pinophyta]], the conifers, which are [[Conifer cone|cone-bearing]] trees and shrubs, and
* [[Biology:Gnetophyta|Gnetophyta]], the gnetophytes, various woody plants in the relict genera ''Ephedra'', ''[[Biology:Gnetum|Gnetum]]'', and ''[[Biology:Welwitschia|Welwitschia]]''.

The fifth extant division is the [[Biology:Flowering plant|flowering plant]]s, also known as angiosperms or magnoliophytes, the largest and most diverse group of spermatophytes:
* [[Biology:Angiosperms|Angiosperms]], the flowering plants, possess seeds enclosed in a [[Biology:Fruit|fruit]], unlike gymnosperms.

In addition to the five living taxa listed above, the fossil record contains evidence of many extinct taxa of seed plants, among those:
* Pteridospermae, the so-called "seed ferns", were one of the earliest successful groups of land plants, and forests dominated by seed ferns were prevalent in the late [[Earth:Paleozoic|Paleozoic]].
* ''[[Biology:Glossopteris|Glossopteris]]'' was the most prominent tree genus in the ancient southern supercontinent of [[Earth:Gondwana|Gondwana]] during the [[Earth:Permian|Permian]] period.
By the [[Earth:Triassic|Triassic]] period, seed ferns had declined in ecological importance, and representatives of modern gymnosperm groups were abundant and dominant through the end of the [[Earth:Cretaceous|Cretaceous]], when the [[Biology:Angiosperms|angiosperms]] radiated.

==Evolutionary history==

[[File:Runcaria megasporangium and cupule drawing.jpg|thumb |upright=0.5 |left |Drawing of ''Runcaria'' megasporangium and cupule, resembling a seed without a solid seed coat]]


A [[Biology:Paleopolyploidy#Whole genome duplication|whole genome duplication event]] in the ancestor of seed plants occurred about {{ma |319}}.<ref name="Jiao2011">{{Cite journal |first1=Yuannian |last1=Jiao |first2=Norman J |last2=Wickett |first3=Saravanaraj |last3=Ayyampalayam |first4=André S |last4=Chanderbali |first5=Lena |last5=Landherr |first6=Paula E. |last6=Ralph |first7=Lynn P. |last7=Tomsho |first8=Yi |last8=Hu |first9=Haiying |last9=Liang |first10=Pamela S. |last10=Soltis |first11=Douglas E. |last11=Soltis |first12=Sandra W. |last12=Clifton |first13=Scott E. |last13=Schlarbaum |first14=Stephan C. |last14=Schuster |first15=Hong |last15=Ma |first16=Jim |last16=Leebens-Mack |first17=Claude W. |last17=dePamphilis |display-authors=3 |year=2011 |title=Ancestral polyploidy in seed plants and angiosperms |journal=Nature |doi=10.1038/nature09916}}</ref> This gave rise to a series of evolutionary changes that resulted in the origin of modern seed plants.

A middle [[Earth:Devonian|Devonian]] (385-million-year-old) [[Biology:Transitional fossil|precursor]] to seed plants from Belgium has been identified predating the earliest seed plants by about 20 million years. ''[[Biology:Runcaria|Runcaria]]'', small and radially symmetrical, is an integumented megasporangium surrounded by a cupule. The megasporangium bears an unopened distal extension protruding above the mutlilobed [[Biology:Integument|integument]]. It is suspected that the extension was involved in anemophilous (wind) [[Biology:Pollination|pollination]]. ''Runcaria'' sheds new light on the sequence of character acquisition leading to the seed. ''Runcaria'' has all of the qualities of seed plants except for a solid seed coat and a system to guide the pollen to the seed.<ref>{{Cite journal |title=Science Magazine |journal=Runcaria, A Middle Devonian Seed Plant Precursor |publisher=American Association for the Advancement of Science |year=2011 |doi=10.1126/science.1102491 |pmid=15514154 |url=https://www.science.org/doi/abs/10.1126/science.1102491 |access-date=March 22, 2011 |archive-date=February 24, 2011 |archive-url=https://web.archive.org/web/20110224214858/http://www.sciencemag.org/content/306/5697/856.abstract |url-status=live |last1=Gerrienne |first1=P. |last2=Meyer-Berthaud |first2=B. |last3=Fairon-Demaret |first3=M. |last4=Streel |first4=M. |last5=Steemans |first5=P. |volume=306 |issue=5697 |pages=856–858 |s2cid=34269432 }}</ref>

''Runcaria'' was followed shortly after by plants with a more condensed cupule, such as ''Spermasporites'' and ''Moresnetia''. Seed-bearing plants had diversified substantially by the [[Earth:Famennian|Famennian]], the last stage of the Devonian. Examples include ''Elkinsia'', ''Xenotheca'', ''Archaeosperma'', "''Hydrasperma''", ''Aglosperma'', and ''Warsteinia''. Some of these Devonian seeds are now classified within the order [[Biology:Lyginopteridales|Lyginopteridales]].<ref>{{Cite journal |last=Anderson |first=John M. |last2=Anderson |first2=Heidi M. |last3=Cleal |first3=Chris J. |date=2007 |title=Brief history of the gymnosperms: classification, biodiversity, phytogeography and ecology |url=http://opus.sanbi.org/bitstream/20.500.12143/5611/1/Strelitzia_20_2007.pdf |journal=Strelitzia |volume=20 |pages=1–280}}</ref>

== Phylogeny ==

Seed-bearing plants are a [[Biology:Clade|clade]] within the vascular plants (tracheophytes).<ref name="Wu  Wang Liu Chaw 2007"/>

=== Internal phylogeny ===


The spermatophytes were traditionally divided into [[Biology:Angiosperm|angiosperm]]s, or flowering plants, and [[Biology:Gymnosperm|gymnosperm]]s, which includes the gnetophytes, cycads,<ref name="Wu  Wang Liu Chaw 2007">{{cite journal | journal=Molecular Biology and Evolution | year=2007 | volume=24 | issue =6 | pages=1366–1379 | doi=10.1093/molbev/msm059 | title=Chloroplast Genome (cpDNA) of Cycas taitungensis and 56 cp Protein-Coding Genes of Gnetum parvifolium: Insights into cpDNA Evolution and Phylogeny of Extant Seed Plants | author=Chung-Shien Wu, Ya-Nan Wang, Shu-Mei Liu and Shu-Miaw Chaw | pmid=17383970 | doi-access=free }}</ref>  ginkgo, and conifers. Older morphological studies believed in a close relationship between the gnetophytes and the angiosperms,<ref name="palmer">{{cite journal | title=The plant tree of life: an overview and some points of view |first1=Jeffrey D. |last1=Palmer|first2=Douglas E. |last2=Soltis |first3=Mark W. |last3=Chase |author-link3=Mark Wayne Chase | journal=American Journal of Botany | year=2004 | volume=91 | pages=1437–1445 | doi=10.3732/ajb.91.10.1437 | issue=10 | pmid=21652302| doi-access=free }}</ref> in particular based on [[Biology:Vessel element|vessel element]]s. However, molecular studies (and some more recent morphological<ref>{{cite journal | journal=The Journal of the Torrey Botanical Society | pages=169–209 | title=Seed ferns and the origin of angiosperms | author=James A. Doyle | volume=133 | issue=1 |date=January 2006 | doi=10.3159/1095-5674(2006)133[169:SFATOO]2.0.CO;2 | s2cid=86302668 | issn=1095-5674 | doi-access=free }}</ref><ref>{{Cite journal |last1=Coiro |first1=Mario |last2=Chomicki |first2=Guillaume |last3=Doyle |first3=James A.|date=n.d. |title=Experimental signal dissection and method sensitivity analyses reaffirm the potential of fossils and morphology in the resolution of the relationship of angiosperms and Gnetales |journal=Paleobiology |volume=44|issue=3 |pages=490–510 |doi=10.1017/pab.2018.23 |s2cid=91488394 |issn=0094-8373}}</ref> and fossil<ref>{{cite journal | title=A New Permian Gnetalean Cone as Fossil Evidence for Supporting Current Molecular Phylogeny | author=Zi-Qiang Wang | journal=Annals of Botany | year=2004 | volume=94 | issue=2 | pages=281–288 | doi=10.1093/aob/mch138 | pmid=15229124 | pmc=4242163 }}</ref> papers) have generally shown a [[Biology:Clade|clade]] of [[Biology:Gymnosperm|gymnosperm]]s, with the gnetophytes in or near the conifers. For example, one common proposed set of relationships is known as the ''gne-pine hypothesis'' and looks like:<ref>{{cite journal | last1=Chaw | first1=Shu-Miaw | last2=Parkinson | first2=Christopher L. | last3=Cheng | first3=Yuchang | last4=Vincent | first4=Thomas M. | last5=Palmer | first5=Jeffrey D. |author-link5=Jeffrey D. Palmer| year=2000 | title=Seed plant phylogeny inferred from all three plant genomes: Monophyly of extant gymnosperms and origin of Gnetales from conifers | journal=Proceedings of the National Academy of Sciences | volume=97 | issue=8| pages=4086–4091 | doi=10.1073/pnas.97.8.4086 | pmid=10760277 | pmc=18157| bibcode=2000PNAS...97.4086C | doi-access=free }}</ref><ref>{{cite journal | last1=Bowe | first1= L. M.| last2=Michelle | first2=L. | last3=Coat | first3=Gwénaële | last4=Claude | year=2000 | title=Phylogeny of seed plants based on all three genomic compartments: Extant gymnosperms are monophyletic and Gnetales' closest relatives are conifers | journal=Proceedings of the National Academy of Sciences | volume=97 | issue=8| pages=4092–4097 | doi=10.1073/pnas.97.8.4092 | pmid=10760278 | pmc=18159| bibcode=2000PNAS...97.4092B| doi-access=free}}</ref><ref>{{cite journal | last1=Soltis | first1=Douglas E. | last2=Soltis | first2=Pamela S. | last3=Zanis | first3=Michael J. | year=2002 | title=Phylogeny of seed plants based on evidence from eight genes | journal=American Journal of Botany | volume=89 | issue=10 | pages=1670–1681 | doi=10.3732/ajb.89.10.1670 | pmid=21665594 | doi-access=free }}</ref>

{{clade| style=font-size:100%;line-height:100%
|label1='''Spermatophytes'''
|1={{clade
   |label1=[[Biology:Angiosperm|Angiosperm]]s |1=(flowering plants) [[File:160 Ranunculus repens.jpg|50px]]
   |label2=[[Biology:Gymnosperm|Gymnosperm]]s
   |2={{clade
      |1=[[Biology:Cycad|Cycad]]s [[File:Cycad illus botanical atlas.jpg|50px]]
      |2=''[[Biology:Ginkgo|Ginkgo]]'' [[File:FB2 Ginkgo (cropped).jpg|50px]]
      |3={{clade
         |1={{clade
            |1=[[Biology:Pinaceae|Pinaceae]] (the pine family) [[File:Pinus pinea tree illustration.jpg|65px]]
            |2=Gnetophytes [[File:Curtis's botanical magazine (8272606272).jpg|80px]]
            }}
         |2=other conifers [[File:Flore des serres v15 147a.jpg|50px]]
         }}
      }}
   }}
}}

However, the relationships between these groups should not be considered settled.<ref name="palmer"/><ref>{{cite journal | title=Dating Dispersal and Radiation in the Gymnosperm Gnetum (Gnetales)—Clock Calibration When Outgroup Relationships Are Uncertain |last1=Won |first1=Hyosig |last2=Renner |first2=Susanne | journal=Systematic Biology | volume=55 | issue=4 |date=August 2006 | pages=610–622 | doi=10.1080/10635150600812619 | pmid=16969937 | doi-access=free }}</ref>

=== Other classifications ===

Other classifications group all the seed plants in a single division, with [[Biology:Class|classes]] for the five groups:{{citation needed|date=January 2024}}
* Division '''Spermatophyta'''
** '''[[Biology:Cycad|Cycad]]opsida''', the cycads
** '''[[Biology:Ginkgoopsida|Ginkgoopsida]]''', the [[Biology:Ginkgo|ginkgo]]
** '''[[Biology:Pinopsida|Pinopsida]]''', the conifers, ("Coniferopsida")
** '''Gnetopsida''', the gnetophytes
** '''[[Biology:Magnoliopsida|Magnoliopsida]]''', the [[Biology:Flowering plant|flowering plant]]s, or '''Angiospermopsida'''

A more modern classification ranks these groups as separate divisions (sometimes under the '''Superdivision Spermatophyta'''):{{citation needed|date=January 2024}}
* '''[[Biology:Cycad|Cycad]]ophyta''', the cycads
* '''[[Biology:Ginkgophyta|Ginkgophyta]]''', the ginkgo
* '''[[Biology:Pinophyta|Pinophyta]]''', the conifers
* '''Gnetophyta''', the gnetophytes
* '''[[Biology:Flowering plant|Magnoliophyta]]''', the flowering plants

Unassigned extinct spermatophyte orders, some of which qualify as "seed ferns":{{citation needed|date=January 2024}}
* †[[Biology:Cordaitales|Cordaitales]]
* †[[Biology:Calamopityales|Calamopityales]]
* †[[Biology:Callistophytales|Callistophytales]]
* †[[Biology:Caytoniales|Caytoniales]]
* †[[Biology:Gigantopteridales|Gigantopteridales]]
* †[[Biology:Glossopteridales|Glossopteridales]]
* †[[Biology:Lyginopteridales|Lyginopteridales]]
* †[[Biology:Medullosales|Medullosales]]
* †[[Biology:Peltaspermales|Peltaspermales]]
* †Umkomasiales (corystosperms)
* †[[Biology:Czekanowskiales|Czekanowskiales]]
* †[[Biology:Bennettitales|Bennettitales]]
* †[[Biology:Erdtmanithecales|Erdtmanithecales]]
* †[[Biology:Pentoxylales|Pentoxylales]]
* †Petriellales <small>Taylor et al. 1994</small>
* †Avatiaceae <small>Anderson & Anderson 2003</small>
* †Axelrodiopsida <small>Anderson & Anderson</small>
* †Alexiales <small>Anderson & Anderson 2003</small>
* †Hamshawviales <small>Anderson & Anderson 2003</small>
* †Hexapterospermales <small>Doweld 2001</small>
* †Hlatimbiales <small>Anderson & Anderson 2003</small>
* †Matatiellales <small>Anderson & Anderson 2003</small>
* †Arberiopsida <small>Doweld 2001</small>
* †Iraniales <small>E. Taylor et al. 2008</small>
* †Vojnovskyales <small>E. Taylor et al. 2008</small>
* †Hermanophytales <small>E. Taylor et al. 2008</small>
* †Dirhopalostachyaceae <small>E. Taylor et al. 2008</small>

== References ==<!-- Syst. Biol. 55(2):245 -->
{{Reflist|2}}

=== Further Reading ===

* Thomas N. Taylor, Edith L. Taylor, and Michael Krings. 2008. ''Paleobotany: The Biology and Evolution of Fossil Plants'', 2nd edition. Academic Press (an imprint of Elsevier): Burlington, MA; New York, NY; San Diego, CA, USA, London, UK. 1252 pages. {{ISBN|978-0-12-373972-8}}.
{{Plant classification}}
{{botany}}
{{Taxonbar|from=Q25814}}


[[Category:Plants]]

{{Sourceattribution|Seed plant}}