Editing Cycad (section)

==Taxonomy==
{{More citations needed|date=November 2018}}
The two extant [[family (biology)|families]] of cycads both belong to the order [[Cycadales]], and are the [[Cycadaceae]] and [[Zamiaceae]] (including [[Stangeriaceae]]). These cycads have changed little since the Jurassic in comparison to some other plant divisions. Five additional families belonging to the [[Medullosales]] became extinct by the end of the Paleozoic Era.

Based on genetic studies, cycads are thought to be more closely related to ''[[Ginkgo]]'' than to other living gymnosperms. Both are thought to have diverged from each other during the early [[Carboniferous]].<ref name="Wu 2013">{{cite journal |last1=Wu |first1=Chung-Shien |last2=Chaw |first2=Shu-Miaw |last3=Huang |first3=Ya-Yi |date=January 2013 |title=Chloroplast phylogenomics indicates that ''Ginkgo biloba'' is sister to cycads |journal=Genome Biology and Evolution |volume=5 |issue=1 |pages=243–254 |doi=10.1093/gbe/evt001 |issn=1759-6653 |pmc=3595029 |pmid=23315384 |language=en}}</ref><ref name="Stull 2021">{{cite journal |last1=Stull  |first1=Gregory W. |last2=Qu |first2=Xiao-Jian |last3=Parins-Fukuchi |first3=Caroline |last4=Yang |first4=Ying-Ying |last5=Yang |first5=Jun-Bo |last6=Yang |first6=Zhi-Yun |last7=Hu |first7=Yi |last8=Ma |first8=Hong |last9=Soltis |first9=Pamela S. |last10=Soltis |first10=Douglas E. |last11=Li |first11=De-Zhu |date=July 19, 2021 |title=Gene duplications and phylogenomic conflict underlie major pulses of phenotypic evolution in gymnosperms |journal=Nature Plants |volume=7 |issue=8 |pages=1015–1025 |doi=10.1038/s41477-021-00964-4 |pmid=34282286 |bibcode=2021NatPl...7.1015S |s2cid=236141481 |issn=2055-0278 |language=en |url=https://www.nature.com/articles/s41477-021-00964-4}}</ref>

{| class="wikitable"
|-
! colspan=1 | External phylogeny<ref name="Wu 2013"/><ref name="Stull 2021"/>
|- 
| style="vertical-align:top|

{| style="border:0; margin:auto;"
|-
|style="padding:10px;"|{{clade
|1={{clade
  |1='''Cycads'''
  |2=''[[Ginkgo]]''
  |3={{clade
    |1=[[Conifers]]
    |label2=Anthophytes
    |2={{clade
      |1=[[Bennettitales]]
      |2=[[Gnetales]]
      |3=[[Angiosperms]]
       }}
     }}
   }}
}}
|style="padding:10px;"|{{clade 
|1={{clade
  |label1=[[Gymnosperm]]s
  |1={{clade 
    |1='''Cycads'''
    |2=''[[Ginkgo]]'' 
    |3={{clade 
      |1=[[Conifers]]
      |2=[[Gnetophytes]]
       }}
     }}
  |label2=[[Angiosperm]]s
  |2=(flowering plants)
   }}
}}
|-
!<br/>{{small|Traditional view}}
!<br/>{{small|Modern view}}
|}
|}

{| class="wikitable"
|-
! colspan=1 | Internal phylogeny<ref name="Nagalingum2011">{{cite journal |last1=Nagalingum |first1=N. S. |last2=Marshall |first2=C. R. |last3=Quental |first3=T. B. |last4=Rai |first4=H. S. |last5=Little |first5=D. P. |last6=Mathews |first6=S. |date=2011 |title=Recent synchronous radiation of a living fossil |journal=Science |volume=334 |issue=6057 |pages=796–799 |bibcode=2011Sci...334..796N |doi=10.1126/science.1209926 |pmid=22021670 |s2cid=206535984}}</ref><ref name="Condamine-2015">{{cite journal |last1=Condamine |first1=Fabien L. |last2=Nagalingum |first2=Nathalie S. |last3=Marshall |first3=Charles R. |last4=Morlon |first4=Hélène |date=17 April 2015 |title=Origin and diversification of living cycads: a cautionary tale on the impact of the branching process prior in Bayesian molecular dating |journal=BMC Evolutionary Biology |volume=15 |issue=1 |at=65 |doi=10.1186/s12862-015-0347-8 |pmid=25884423|s2cid=14815027 |language=en |doi-access=free|pmc=4449600 |bibcode=2015BMCEE..15...65C }}</ref>
|- 
| style="vertical-align:top|

{| style="border:0; margin:auto;"
|-
|style="padding:10px;"|{{clade|style=font-size:90%;line-height:80%;width:300px
|label1 =Cycads
|1={{clade
  |label1=Cycadineae
  |1={{clade
    |label1=[[Cycadaceae]]
    |1=''[[Cycas]]''
     }}
  |label2=Zamiineae
  |2={{clade
    |label1=[[Zamiaceae]]
    |1={{clade
      |label1=Diooideae
      |1=''[[Dioon]]''
      |label2=Zamioideae
      |2={{clade
        |label1=Encephalarteae
        |1={{clade
          |1=''[[Macrozamia]]''
          |2={{clade
            |1=''[[Lepidozamia]]''
            |2=''[[Encephalartos]]''
             }}
           }}
        |label2=Zamieae
        |2={{clade
          |1=''[[Bowenia]]''
          |2={{clade
            |1={{clade
              |1=''[[Ceratozamia]]''
              |2=''[[Stangeria]]''
               }}
            |2={{clade
              |1=''[[Zamia]]''
              |2=''[[Microcycas]]''
               }}
             }}
           }}
         }}
       }}
     }}
   }}
}}
|}
|}

Classification of the Cycadophyta to the rank of family.

* Class Cycadopsida <small>Brongniart 1843</small>
** Order Cycadales <small>Persoon ex von Berchtold & Presl 1820</small>
*** Suborder Cycadineae <small>Stevenson 1992</small>
**** Family [[Cycadaceae]] <small>Persoon 1807</small>
***** Genus ''[[Cycas]]''
*** Suborder Zamiineae <small>Stevenson 1992</small>
**** Family [[Zamiaceae]] <small>Horaninow 1834</small>
***** subfamily Diooideae <small>Pilg. 1926</small>
****** Tribe Diooeae <small>Schuster</small>
******* Genus ''[[Dioon]]''
***** subfamily Zamioideae <small>Stevenson 1992</small>
****** Tribe Encephalarteae <small>Miquel 1861</small>
******* Genus ''[[Macrozamia]]''
******* Genus ''[[Lepidozamia]]''
******* Genus ''[[Encephalartos]]''
****** Tribe Zamieae <small>Miquel 1861</small>
******* Genus ''[[Bowenia]]''
******* Genus ''[[Ceratozamia]]''
******* Genus ''[[Stangeria]]''
******* Genus ''[[Zamia]]''
******* Genus ''[[Microcycas]]''

=== Fossil genera ===
The following extinct cycad genera are known:<ref>{{Cite web |title=PBDB |url=https://paleobiodb.org/classic/basicTaxonInfo?taxon_no=55349 |access-date=2024-03-16 |website=paleobiodb.org}}</ref>

* ''[[Amuriella]]'' Late Jurassic, Russian Far East (leaf fragments)
* ''[[Androstrobus]]'' Triassic to Cretaceous, worldwide (leaf form genus)
* ''[[Antarcticycas]]'' Middle Triassic, Antarctica (known from the whole plant)<ref>{{Cite journal |last1=Hermsen |first1=Elizabeth J. |last2=Taylor |first2=Edith L. |last3=Taylor |first3=Thomas N. |date=January 2009 |title=Morphology and ecology of the ''Antarcticycas'' plant |journal=Review of Palaeobotany and Palynology |language=en |volume=153 |issue=1–2 |pages=108–123 |doi=10.1016/j.revpalbo.2008.07.005|bibcode=2009RPaPa.153..108H }}</ref>
* ?''[[Anthrophyopsis]]'' Late Triassic, worldwide (leaf form genus, possibly a [[Pteridospermatophyta|pteridospermatophyte]])<ref>{{Cite journal |last1=Xu |first1=Yuanyuan |last2=Popa |first2=Mihai Emilian |last3=Zhang |first3=Tingshan |last4=Lu |first4=Ning |last5=Zeng |first5=Jianli |last6=Zhang |first6=Xiaoqing |last7=Li |first7=Liqin |last8=Wang |first8=Yongdong |date=2021-09-01 |title=Re-appraisal of Anthrophyopsis (Gymnospermae): New material from China and global fossil records |url=https://www.sciencedirect.com/science/article/pii/S0034666721000993 |journal=Review of Palaeobotany and Palynology |volume=292 |pages=104475 |doi=10.1016/j.revpalbo.2021.104475 |bibcode=2021RPaPa.29204475X |issn=0034-6667|url-access=subscription }}</ref>
* ''[[Apoldia]]'' Triassic-Jurassic, Europe
* ''[[Archaeocycas]]'' Early Permian, Texas (leaf with sporophylls)
* ''[[Aricycas]]'' Late Triassic, Arizona (leaf form genus)
* ''[[Beania (plant)|Beania]]'' (=''Sphaereda''), Triassic to Jurassic, Europe & Central Asia (leaf form genus)
* ''[[Behuninia]]'' Late Jurassic, Colorado & Utah (fruiting structures)
* ''[[Bucklandia]]'' Middle Jurassic to Early Cretaceous, Europe and India (leaf form genus)
* ''[[Bureja (genus)|Bureja]]'' Late Jurassic, Russia
* ''[[Cavamonocolpites]]'' Early Cretaceous, Brazil (pollen)
* ''[[Crossozamia]]'' Early to Late Permian, China (leaf form genus)
* ''[[Ctenis]]'' Mesozoic-Paleogene, Worldwide (leaf form genus)
* ''[[Ctenozamites]]'' Triassic-Cretaceous, worldwide (leaf form genus)
* ''[[Cycadenia]]'' Triassic, Pennsylvania (trunks)
* ''[[Cycadinorachis]]'' Late Jurassic, India (rachis)
* ''[[Fascisvarioxylon]]'' Late Jurassic, India (petrified wood)
* ''[[Gymnovulites]]'', Latest Cretaceous/earliest Paleocene, India (seed)
* ''[[Heilungia]]'', Late Jurassic to early Cretaceous, Russia & Alaska (leaf form genus)
* ''[[Leptocycas]]'' Late Triassic, North Carolina & China (known from the whole plant)<ref>{{Cite journal |last1=Zhang |first1=Jian-Wei |last2=Yao |first2=Jian-Xin |last3=Chen |first3=Jia-Rui |last4=Li |first4=Cheng-Sen |date=2010-05-25 |title=A new species of Leptocycas (Zamiaceae) from the Upper Triassic sediments of Liaoning Province, China |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1759-6831.2010.00079.x |journal=Journal of Systematics and Evolution |language=en |volume=48 |issue=4 |pages=286–301 |doi=10.1111/j.1759-6831.2010.00079.x|bibcode=2010JSyEv..48..286Z }}</ref>
* ''[[Mesosingeria]]'', Jurassic to Early Cretaceous, Antarctica & Argentina (leaf form genus)
* ''[[Michelilloa]]'', Late Triassic, Argentina (stem)
* ?''[[Nikania]]'', Early Cretaceous, Russia (leaf fragments)
* ?''[[Nilssonia (plant)|Nilssonia]]'', Middle Permian to Late Cretaceous, worldwide (leaf form genus) (possibly not a cycad)<ref>{{Cite journal |last1=Vajda |first1=Vivi |last2=Pucetaite |first2=Milda |last3=McLoughlin |first3=Stephen |last4=Engdahl |first4=Anders |last5=Heimdal |first5=Jimmy |last6=Uvdal |first6=Per |date=August 2017 |title=Molecular signatures of fossil leaves provide unexpected new evidence for extinct plant relationships |url=https://www.nature.com/articles/s41559-017-0224-5 |journal=Nature Ecology & Evolution |language=en |volume=1 |issue=8 |pages=1093–1099 |bibcode=2017NatEE...1.1093V |doi=10.1038/s41559-017-0224-5 |issn=2397-334X |pmid=29046567 |s2cid=3604369}}</ref>
* ?''[[Nilssoniocladus]]'', Early to Late Cretaceous, United States & Russia (stems, likely associated with ''Nilssonia'', possibly [[deciduous]])<ref>{{Cite journal |last1=Spicer |first1=Robert A. |last2=Herman |first2=Alexey B. |date=1996-05-01 |title=Nilssoniocladus in the Cretaceous Arctic: new species and biological insights |url=https://dx.doi.org/10.1016/0034-6667%2895%2900111-5 |journal=Review of Palaeobotany and Palynology |volume=92 |issue=3 |pages=229–243 |doi=10.1016/0034-6667(95)00111-5 |bibcode=1996RPaPa..92..229S |issn=0034-6667|url-access=subscription }}</ref>
* ''[[Palaeozamia]]'', Middle Jurassic, England
* ''[[Paracycas]]'', Middle Jurassic to Late Jurassic, Europe and Central Asia
* ?''[[Phasmatocycas]]'', Late Carboniferous to Early Permian, Kansas, Texas & New Mexico (leaf with sporophylls)<ref>{{Cite journal |last1=Axsmith |first1=Brian J. |last2=Serbet |first2=Rudolph |last3=Krings |first3=Michael |last4=Taylor |first4=Thomas N. |last5=Taylor |first5=Edith L. |last6=Mamay |first6=Sergius H. |date=2003 |title=The Enigmatic Paleozoic plants Spermopteris and Phasmatocycas reconsidered |url=https://bsapubs.onlinelibrary.wiley.com/doi/10.3732/ajb.90.11.1585 |journal=American Journal of Botany |language=en |volume=90 |issue=11 |pages=1585–1595 |doi=10.3732/ajb.90.11.1585 |pmid=21653333 |bibcode=2003AmJB...90.1585A |issn=0002-9122|url-access=subscription }}</ref>
* ''[[Pleiotrichium]]'', Late Cretaceous, Germany (leaf)
* ''[[Pseudoctenis]]'', Late Permian to Late Cretaceous, worldwide (leaf form genus)
* ''[[Sarmatiella]]'', Late Triassic, Ukraine 
* ''[[Stangerites]]'', Late Triassic to Early Jurassic, Virginia and Mexico (leaf form genus)
* ''[[Sueria]]'', Early Cretaceous, Argentina (leaf)
* ''[[Taeniopteris]]'', Carboniferous to Cretaceous, worldwide (polyphyletic leaf form genus, also includes bennettitales and [[Marattiales|marattialean]] ferns)