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Cycas

{{Short description|Genus of cycads in the family Cycadaceae}}

{{Automatic taxobox

| oldest_fossil = Paleogene

| image = Big Cycas.jpg

| image_caption = A large cycas under development

| display_parents = 2

| parent_authority = Pers.{{cite book |doi=10.1007/978-3-662-02604-90.0 |chapter=Cycadaceae |title=Pteridophytes and Gymnosperms |date=1990 |last1=Johnson |first1=L. A. S. |last2=Wilson |first2=K. L. |page=370 |doi-broken-date=4 March 2025 |isbn=978-3-642-08080-7 }}

| taxon = Cycas

| authority = L.{{cite web|last=Hill|first=Ken|title=The Cycad Pages|url=https://plantnet.rbgsyd.nsw.gov.au/PlantNet/cycad/cyckey.html |archive-url=https://web.archive.org/web/20210301203939/https://plantnet.rbgsyd.nsw.gov.au/PlantNet/cycad/cyckey.html |archive-date=2021-03-01 |work=Genus Cycas|publisher=Royal Botanic Gardens Sydney|access-date=6 September 2013 |author2=Leonie Stanberg |author3=Dennis Stevenson}}

| type_species = C. circinalis

| type_species_authority = L.

| synonyms_ref = {{R|POWO}}

| synonyms =

  • Dyerocycas Nakai
  • Epicycas de Laub.
  • Todda-pana Adans.

| range_map = Répartitions des Cycas.png

}}

Cycas is a genus of cycad, and the only genus in the family Cycadaceae with all other genera of cycad being divided between the Stangeriaceae and Zamiaceae families. Cycas circinalis, a species endemic to India, was the first cycad species to be described in western literature, and is the type species of the genus.{{Cite book |last=Linnaeus |first=Carl |title=Palmae Pennatifoliae. Cycas [Cycas circinalis protologue] |year=1753 |pages=Sp. Pl. 2 : 1188}}Type Location(s): LT:t. 19, in Rheede, Hort. Malab, 3 (1682)

[https://www.cycadlist.org/taxon.php?Taxon_ID=87 Cycas circinalis at The World List of Cycads] (cycadlist.org)

As of April 2024, there are 119 accepted species within the genus Cycas, all of which are native to Asia, Oceania, and eastern Africa and the Indian ocean region, with the largest number of species native to Australia, China and Vietnam.119 accepted species, with 6 infraspecific taxa, as of April 21, 2024.The World List of Cycads (WLoC), a comprehensive taxonomic reference for cycad taxonomy, nomenclature, biology, and literature. The WLoC is produced under the auspices of the [http://www.cycadgroup.org/ IUCN/SSC Cycad Specialist Group (CSG)]. The online edition is hosted and sponsored by [https://www.montgomerybotanical.org/ Montgomery Botanical Center].

Calonje M, Stevenson DW, Osborne R. The World List of Cycads, online edition [Internet]. 2013-2024. [cited 2024 Apr 21]. Available from: [http://www.cycadlist.org/ http://www.cycadlist.org].{{Cite journal |last1=Donaldson, J.S. |last2=Dehgan, B. |last3=Vovides, A.P. |last4=Tang, W. |date=2003 |title=Cycads in trade and sustainable use of cycad populations |url=https://portals.iucn.org/library/efiles/documents/2003-010.pdf |journal=Cycads Status Survey and Conservation Action Plan |location=IUCN The World Conservation Union Gland, Switzerland}}

In horticulture, the most widely grown and perhaps best-known Cycas species is Cycas revoluta, which is commercially grown in large numbers for sale as houseplants or to be used in landscaping.{{Cite web |title=Cycas revoluta |url=https://cycadlist.org/taxon.php?Taxon_ID=191 |access-date=2024-04-21 |website=cycadlist.org}}{{cite journal |last1=Marler |first1=Thomas E. |last2=Moore |first2=Aubrey |title=Cryptic Scale Infestations on Cycas revoluta Facilitate Scale Invasions |journal=HortScience |date=May 2010 |volume=45 |issue=5 |pages=837–839 |doi=10.21273/HORTSCI.45.5.837 |doi-access=free }}

The majority of Cycas species are highly endangered. Many are threatened by the illegal trade of wild collected plants for plant collectors, and through the conversion of land for urban development or agricultural use.

Range

{{See also|List of cycad species by country}}

The genus Cycas is native to parts of Asia, eastern Africa and Oceania. Cycas has the widest distribution of any genus of cycad.Hill, K. D. (2004). Character evolution, species recognition and classification concepts in the Cycadaceae In Walters T., & Osborne R. (Eds.), Cycad classification, concepts and recommendations (pp. 23–44). Wallingford: CABI Publishing.Available as a PDF online at: [https://www.cabidigitallibrary.org/doi/pdf/10.5555/20043021917 cabidigitallibrary.org]

In Asia, Cycas (and therefore, the family Cycadaceae) represent the only cycads native to Asia. Within Asia, Cycas species are native from India and Sri Lanka in the west, through China to Japan in the north east and through south east Asia (including the Philippines) to Indonesia in the south. Globally, the northernmost species ( Cycas revoluta) is found at 31°N in southern Japan.

As of April 2024, the largest number of currently accepted species of Cycas in Asia are found in Vietnam (27 species), China (23 species), India (14 species), Thailand (12 species), Philippines (12 species) and Indonesia (10 species). The distribution of Cycas species in Myanmar, Laos, and Cambodia is not well known, but as of April 2024, no accepted cycad species is known to be endemic to any of these three countries.

In Africa, cycads belonging to all three cycad families are found making it a major center of diversity for cycads in general, but only one Cycas species (Cycas thouarsii) is native and it is restricted to eastern Africa and nearby island nations. C. thouarsii grows in a comparatively wide area including coastal regions of Mozambique, Tanzania, and Kenya in mainland Africa, extending to the Seychelles, Madagascar and Comoros islands in the Indian Ocean.{{Cite web |title=Cycas thouarsii |url=https://cycadlist.org/taxon.php?Taxon_ID=228 |access-date=2024-04-21 |website=cycadlist.org}}

In Oceania, Cycas species are native to Australia, Papua New Guinea, and the island nations of the Pacific Ocean region, but are absent from New Zealand. As in Asia, Cycas is the only genus of cycad found across the region, with the exception for Australia, where cycads native to all three families of cycads are found. Despite this, Australia also has the largest number of Cycas species globally with 34 native Cycas species accepted (as of April 2024), including the southernmost species globally (Cycas megacarpa) found at 26°S in southeast Queensland.{{Cite web |title=Cycas megacarpa |url=https://cycadlist.org/taxon.php?Taxon_ID=162 |access-date=2024-04-21 |website=cycadlist.org}} At least 7 Cycas species are found in Papua New Guinea, some of which are also found in parts of neighbouring Indonesia. In the broader region, Cycas seemannii is found in Melanesia and western Polynesia and Cycas micronesica is found across Micronesia.{{Cite web |title=Cycas seemannii |url=https://cycadlist.org/taxon.php?Taxon_ID=206 |access-date=2024-04-21 |website=cycadlist.org}}{{Cite web |title=Cycas micronesica |url=https://cycadlist.org/taxon.php?Taxon_ID=165 |access-date=2024-04-21 |website=cycadlist.org}}

Globally, some Cycas species are considered to be relatively widespread, for example Cycas thouarsii is native to a large area of mainland Africa and islands of the Indian Ocean, and Cycas pectinata and Cycas clivicola are both native to large areas of Asia; however, most Cycas species have restricted distributions, with some restricted to very small areas. In Asia, for example, more than 75% of species occur in no more than one country. For some countries, even though the number of species may not be high, the level of species-specific genetic variation can be very high meaning that so that even countries with few species, it may contain distinct gene pools of widespread species.{{cite journal |last1=Xiao |first1=Siyue |last2=Ji |first2=Yunheng |last3=Liu |first3=Jian |last4=Gong |first4=Xun |title=Genetic characterization of the entire range of Cycas panzhihuaensis (Cycadaceae) |journal=Plant Diversity |date=February 2020 |volume=42 |issue=1 |pages=7–18 |doi=10.1016/j.pld.2019.10.001 |pmid=32140633 |pmc=7046506 |bibcode=2020PlDiv..42....7X }}

Evolution

File:Cycus tici.jpg

Cycas (and the Cycadaceae family) is considered as being an early offshoot that diverged early from all other living cycads (which belong to the family Zamiaceae). Estimates of the timing of the split ranging from the Jurassic{{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. |title=Recent Synchronous Radiation of a Living Fossil |journal=Science |date=11 November 2011 |volume=334 |issue=6057 |pages=796–799 |doi=10.1126/science.1209926 |pmid=22021670 |bibcode=2011Sci...334..796N |s2cid=206535984 }} to the Carboniferous. The earliest fossils assignable to Cycas are known from the Paleogene of East Asia, such as Cycas fushunensis from the Eocene (around 47.5 million years ago) of Northeast China with East Asia likely representing the ancestral homeland of the genus.{{cite journal |last1=Liu |first1=Jian |last2=Lindstrom |first2=Anders J |last3=Marler |first3=Thomas E |last4=Gong |first4=Xun |date=28 January 2022 |title=Not that young: combining plastid phylogenomic, plate tectonic and fossil evidence indicates a Palaeogene diversification of Cycadaceae |journal=Annals of Botany |volume=129 |issue=2 |pages=217–230 |doi=10.1093/aob/mcab118 |pmc=8796677 |pmid=34520529}} The presence of Cycas in Australasia and eastern Africa is relatively new, but the major evolutionary events behind the genesis of new species have taken place in Indochina and Australia, where the majority of living species are native.

Fossil seeds from the Middle Jurassic of England and British Columbia were suggested in a 2017 study to be more closely related to Cycas than other cycads and were assigned to the same family, Cycadaceae.{{Cite journal |last1=Spencer |first1=Alan R. T. |last2=Garwood |first2=Russell J. |last3=Rees |first3=Andrew R. |last4=Raine |first4=Robert J. |last5=Rothwell |first5=Gar W. |last6=Hollingworth |first6=Neville T. J. |last7=Hilton |first7=Jason |date=2017-08-28 |title=New insights into Mesozoic cycad evolution: an exploration of anatomically preserved Cycadaceae seeds from the Jurassic Oxford Clay biota |journal=PeerJ |language=en |volume=5 |pages=e3723 |doi=10.7717/peerj.3723 |issn=2167-8359 |pmc=5578371 |pmid=28875075 |doi-access=free }} A later study suggested that these seeds could not be assigned to the stem-group of Cycas with confidence due to lacking the double vascular system that characterises the seeds of all living cycads.{{cite journal |last1=Rothwell |first1=Gar W. |last2=Stockey |first2=Ruth A. |last3=Stevenson |first3=Dennis W. |last4=Zumajo-Cardona |first4=Cecilia |title=Large Permineralized Seeds in the Jurassic of Haida Gwaii, Western Canada: Exploring the Mode and Tempo of Cycad Evolution |journal=International Journal of Plant Sciences |date=October 2022 |volume=183 |issue=8 |pages=674–690 |doi=10.1086/721710 |hdl=2434/975729 |hdl-access=free }} The leaf fossil genus Paracycas known from the Jurassic and Cretaceous of Europe has been suggested to be early representatives of the Cycas lineage by cladistic analysis.{{Cite journal |last1=Coiro |first1=Mario |last2=Allio |first2=Rémi |last3=Mazet |first3=Nathan |last4=Seyfullah |first4=Leyla J. |last5=Condamine |first5=Fabien L. |date=2023-06-11 |title=Reconciling fossils with phylogenies reveals the origin and macroevolutionary processes explaining the global cycad biodiversity |journal=New Phytologist |volume=240 |issue=4 |pages=1616–1635 |language=en |doi=10.1111/nph.19010 |pmid=37302411 |pmc=10953041 |bibcode=2023NewPh.240.1616C |s2cid=259137975 |issn=0028-646X}}

Image:Rumphii1562.jpg

Image:Cycas male cone.jpg]]

{{Multiple image

|title = Cycas native to Odisha

|image1 = Cycas nayagarhensis Singh Radha Khuraijam.JPG

|image2 = Cycas orixensis Singh Khuraijam.JPG

|caption1 = Cycas nayagarhensis male cone

|caption2 = Cycas orixensis male cone

}}

Conservation status

Cycas species are threatened worldwide and almost all the species are listed in the IUCN Red List. Cycas beddomei is the only species of the genus Cycas listed in Appendix I of CITES. All other members of Cycadaceae are listed under Appendix II.{{cite web|url=https://cites.org/eng/app/appendices.php|title=Appendices I, II and III|website=Convention on International Trade in Endangered Species of Wild Fauna and Flora|date=21 May 2023|access-date=22 August 2023}} Cycas rumphii and Cycas pectinata have the most widespread distribution.{{cn|date=February 2025}}

Phylogeny

File:Cycas media megasporophylls.jpg megasporophylls with nearly-mature seeds on a wild plant in north Queensland, Australia]]

File:Cycas media.JPG in north Queensland]]

File:Cycas platyphylla with new flush of fronds.JPG in north Queensland with new flush of fronds during the rainy season, still with glaucous bloom]]

class="wikitable"
colspan=1 |Phylogeny of Cycas{{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 |last12=Smith |first12=Stephen A. |last13=Yi |first13=Ting-Shuang |title=Gene duplications and phylogenomic conflict underlie major pulses of phenotypic evolution in gymnosperms |journal=Nature Plants |date=19 July 2021 |volume=7 |issue=8 |pages=1015–1025 |doi=10.1038/s41477-021-00964-4 |pmid=34282286 |bibcode=2021NatPl...7.1015S }}
style="vertical-align:top|

{{clade|style=font-size:90%;line-height:80%

|1={{clade

|1={{clade

|label1=section

|sublabel1=Stangerioides

|1=C. micholitzii Dyer

}}

|2={{clade

|1={{clade

|label1=(Pectinata)

|1={{clade

|1=C. multipinnata C.J.Chen & S.Y.Yang

|2=C. pectinata Buch.-Ham.

}}

}}

|2={{clade

|1=C. thouarsii R.Br. ex Gaudichaud-Beaupré

|2={{clade

|label1=(Panzhihuaenses)

|1={{clade

|label1=section

|sublabel1=Asiorientales

|1={{clade

|1=C. revoluta Thunb. (Sago palm)

|2=C. taitungensis Shen et al.

}}

|label2=section

|sublabel2=Panzhihuaenses

|2={{clade

|1=C. tropophylla K.D.Hill & P.K.Lôc

|2={{clade

|1=C. ferruginea F.N.Wei

|2={{clade

|1=C. curranii (J.Schust.) K.D.Hill

|2={{clade

|1=C. debaoensis Y.C.Zhong & C.J.Chen

|2={{clade

|1=C. brachycantha K.D.Hill, H.T.Nguyen & P.K.Lôc

|2=C. immersa Craib

}}

}}

}}

}}

}}

}}

|label2=(Cycas)

|2={{clade

|1=C. bifida (Dyer) K.D.Hill

|2={{clade

|1=C. szechuanensis W.C.Cheng & L.K.Fu

|2={{clade

|1={{clade

|label1=section

|sublabel1=Wadeanae

|1={{clade

|label1=subsection

|sublabel1=Wadeanae

|1=C. wadei Merr.

|label2=subsection

|sublabel2=Taiwanianosae

|2={{clade

|1=C. hainanensis C.J.Chen

|2={{clade

|1=C. taiwaniana Carruthers

|2=C. fairylakea D.Y.Wang

}}

}}

}}

}}

|2={{clade

|label1=section

|sublabel1=Cycas

|1={{clade

|label1=subsection

|sublabel1=Cycas

|1={{clade

|1=C. circinalis L. (Indu)

|2=C. micronesica K.D.Hill

}}

|label2=subsection

|sublabel2=Rumphiae

|2={{clade

|1=C. pschannae R.C.Srivast. & L.J.Singh

|2={{clade

|1=C. edentata de Laub.

|2={{clade

|1=C. nitida K.D.Hill & A.Lindstr.

|2=C. rumphii Miq.

}}

}}

}}

}}

|2={{clade

|label1=section

|sublabel1=Indosinenses

|1={{clade

|1=C. clivicola K.D.Hill

|2={{clade

|label1=subsection

|sublabel1=Indosinenses

|1={{clade

|1=C. siamensis Miq.

|2={{clade

|1=C. vespertilio A.Lindstr. & K.D.Hill

|2={{clade

|1=C. riuminiana M.Porte ex Regel

|2={{clade

|1=C. bougainvilleana K.D.Hill

|2=C. celebica Miq.

}}

}}

}}

}}

|label2=subsection

|sublabel2=Lindstroemiae

|2={{clade

|1=C. macrocarpa Griff.

|2={{clade

|1=C. nongnoochiae K.D.Hill

|2={{clade

|1=C. elongata (Leandri) D.Y.Wang

|2={{clade

|1=C. tansachana K.D.Hill & S.L.Yang

|2={{clade

|1=C. lindstromii S.L.Yang, K.D.Hill & Nguyên

|2={{clade

|1=C. condaoensis K.D.Hill & S.L.Yang

|2={{clade

|1=C. chamaoensis K.D.Hill

|2=C. media R.Br.

}}

}}

}}

}}

}}

}}

}}

}}

}}

|label2=section

|sublabel2=Endemicae

|2={{clade

|1=C. diannanensis Z.T.Guan & G.D.Tao

|2={{clade

|1=C. cairnsiana F.Muell.

|2={{clade

|1=C. petrae A.Lindstr. & K.D.Hill

|2={{clade

|1=C. megacarpa K.D.Hill

|2={{clade

|1=C. calcicola Maconochie

|2={{clade

|1=C. armstrongii Miq.

|2={{clade

|1=C. balansae Warb.

|2={{clade

|1=C. segmentifida D.Y.Wang & C.Y.Deng

|2={{clade

|1=C. dolichophylla K.D.Hill, H.T.Nguyen & P.K.Lôc

|2={{clade

|1=C. simplicipinna (Smitinand) K.D.Hill

|2={{clade

|1=C. guizhouensis K.M.Lan & R.F.Zou

|2={{clade

|1=C. chevalieri Leandri

|2={{clade

|1=C. maconochiei Chirgwin & K.D.Hill

|2={{clade

|1=C. arenicola K.D.Hill

|2={{clade

|1={{clade

|1=C. schumanniana Lauterb.

|2={{clade

|1=C. aculeata K.D.Hill & H.T.Nguyen

|2=C. silvestris K.D.Hill

}}

}}

|2={{clade

|1=C. basaltica C.A.Gardner

|2={{clade

|1=C. semota K.D.Hill

|2={{clade

|1=C. orientis K.D.Hill

|2={{clade

|1=C. canalis K.D.Hill

|2={{clade

|1=C. hongheensis S.Y.Yang & S.L.Yang

|2={{clade

|1=C. conferta Chirgwin

|2={{clade

|1=C. angulata R.Br.

|2={{clade

|1={{clade

|1=C. couttsiana K.D.Hill

|2={{clade

|1=C. ophiolitica K.D.Hill

|2={{clade

|1=C. tanqingii D.Y.Wang

|2=C. platyphylla K.D.Hill

}}

}}

}}

|2={{clade

|1=C. indica A.Lindstr. & K.D.Hill (=Cycas swamyi)

|2={{clade

|1=C. annaikalensis Rita Singh & P.Radha

|2={{clade

|1=C. beddomei Dyer

|2=C. sphaerica Roxb.

}}

}}

}}

}}

}}

}}

}}

}}

}}

}}

}}

}}

}}

}}

}}

}}

}}

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Other species:

{{div col|colwidth=18em}}

{{div col end}}

References

{{Reflist|refs=

{{cite web |url=https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:326847-2 |title=Cycas L. |website=Plants of the World Online |publisher=Royal Botanic Gardens, Kew |access-date=28 March 2023}}

}}

External links

  • {{cite journal | last1 = de Laubenfels | first1 = D.J. | last2 = Adema | first2 = F. | year = 1998 | title = A taxonomic revision of the genera Cycas and Epicycas Gen. Nov. (Cycadaceae) | url =http://www.repository.naturalis.nl/document/565822 | journal = Blumea | volume = 43 | pages = 351–400 }}
  • Hill, K.D.(1998–2004) The Cycad Pages, Royal Botanic Gardens Sydney. http://plantnet.rbgsyd.nsw.gov.au/PlantNet/cycad/index.html {{Webarchive|url=https://web.archive.org/web/20210329132148/https://plantnet.rbgsyd.nsw.gov.au/PlantNet/cycad/index.html |date=2021-03-29 }}
  • [https://web.archive.org/web/20080403033422/http://www.plantapalm.com/vce/vce_index.htm Virtual Cycad Encyclopedia] edited by the Palm & Cycad Societies of Florida
  • David, J. de Laubenfels, [https://web.archive.org/web/20090213143743/http://delaubenfels.com/content/blogcategory/18/78/ Cycas Taxonomy]
  • {{cite journal | last1 = Hill | first1 = K.D. | last2 = Stevenson | first2 = Dennis W. | last3 = Osborne | first3 = Roy | year = 2004 | title = The World List of Cycads | journal = The Botanical Review | volume = 70 | issue = 2| pages = 274–298 | doi = 10.1663/0006-8101(2004)070[0274:TWLOC]2.0.CO;2 | s2cid = 36921733 }}
  • {{cite journal | last1 = Lindstrom | first1 = Anders J. | last2 = Hill | first2 = Ken D. | year = 2007 | title = The genus Cycas (Cycadaceae) in India | url = http://plantnet.rbgsyd.nsw.gov.au/emuwebnswlive/objects/common/webmedia.php?irn=46748&reftable=ebibliography | journal = Telopea | volume = 11 | issue = 4| pages = 463–488 | doi=10.7751/telopea20075745| doi-access = free }}
  • Singh, R & JS Khuraijam (2013-) Cycads of India. http://www.cycadsofindia.in/ {{Webarchive|url=https://web.archive.org/web/20210118092551/http://www.cycadsofindia.in/ |date=2021-01-18 }}
  • {{cite journal | last1 = Singh | first1 = R. | last2 = Radha | first2 = P. | last3 = Khuraijam | first3 = J.S. | year = 2015 | title = A new species, a new combination and a new subsection of Cycas from Odisha, northern Eastern Ghats of India | journal = Asian Journal of Conservation Biology | volume = 4 | issue = 1| pages = 3–14 }}
  • {{cite journal | last1 = Singh | first1 = R. | last2 = Radha | first2 = P. | year = 2006 | title = Cycas annaikalensis, A new species of Cycas from the Malabar Coast, Western Ghats, India | journal = Brittonia | volume = 58 | issue = 2| pages = 119–123 | doi=10.1663/0007-196x(2006)58[119:ansocf]2.0.co;2| s2cid = 32241023 }}
  • Terrence Walters & Roy Osborne (eds.) (2004), Cycad Classification: Concepts and Recommendations, CABI publishing, {{ISBN|0-85199-741-4}}

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{{Acrogymnospermae classification}}

{{Taxonbar|from=Q161073}}

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Category:Plants described in 1753

Category:Taxa named by Carl Linnaeus

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