cycad#Conservation

File: Cycad leaves semicircle.jpg

Cycads have a cylindrical trunk which usually does not branch. However, some types of cycads, such as Cycas zeylanica, can branch their trunks. The apex of the stem is protected by modified leaves called cataphylls.{{cite journal | pmc=6315973 | year=2018 | last1=Marler | first1=T. E. | last2=Krishnapillai | first2=M. V. | title=Does Plant Size Influence Leaf Elements in an Arborescent Cycad? | journal=Biology | volume=7 | issue=4 | page=51 | doi=10.3390/biology7040051 | pmid=30551676 | doi-access=free }} Leaves grow directly from the trunk, and typically fall when older, leaving a crown of leaves at the top. The leaves grow in a rosette, with new foliage emerging from the top and center of the crown. The trunk may be buried, so the leaves appear to be emerging from the ground, so the plant appears to be a basal rosette. The leaves are generally large in proportion to the trunk size, and sometimes even larger than the trunk.

The leaves are pinnate (in the form of bird feathers, pinnae), with a central leaf stalk from which parallel "ribs" emerge from each side of the stalk, perpendicular to it. The leaves are typically either compound (with leaflets emerging from the leaf stalk as "ribs"), or have edges (margins) so deeply cut (incised) so as to appear compound. The Australian genus Bowenia and some Asian species of Cycas, like Cycas multipinnata, C. micholitzii and C. debaoensis, have leaves that are bipinnate, the leaflets each having their own subleaflets, growing in the same form on the leaflet as the leaflets do on the stalk.{{Cite book |last=Rutherford |first=Catherine |url=https://www.kew.org/sites/default/files/2019-02/CITESCycadsPack.pdf.pdf |title=CITES and Cycads: A User's Guide |publisher=Royal Botanic Gardens, Kew |display-editors=et al.}}{{cite book | url=https://books.google.com/books?id=_EMbBAAAQBAJ&dq=C.+multipinnata+within+the+genus.+C.+debaoensis&pg=PA129 | title=Cycadaceae Family | isbn=9781300654537 | last1=Lariushin | first1=Boris | date=19 January 2013 | publisher=Lulu.com }}

Due to superficial similarities in foliage and plant structure, cycads and palms are often mistaken for each other. They also can occur in similar climates. However, they belong to different phyla and as such are not closely related. The similar structure is the product of convergent evolution.

Beyond those superficial resemblances, there are a number of differences between cycads and palms. For one, cycads are gymnosperms and bear cones (strobili), while palms are angiosperms and so flower and bear fruit. The mature foliage looks similar between both groups, but the young emerging leaves of a cycad resemble a fiddlehead fern before they unfold and take their place in the rosette, while the leaves of palms are just small versions of the mature frond. Another difference is in the stem. Both plants leave some scars on the stem below the rosette where there used to be leaves, but the scars of a cycad are helically arranged and small, while the scars of palms are a circle that wraps around the whole stem. The stems of cycads are also in general rougher and shorter than those of palms.{{Cite book |title=The Tree |last=Tudge |first=Colin |publisher=Crown Publishers |year=2006 |isbn=978-1-4000-5036-9 |location=New York |pages=[https://archive.org/details/treenaturalhisto00tudg/page/70 70–72, 139–148] |url-access=registration |url=https://archive.org/details/treenaturalhisto00tudg}}

{{More citations needed|date=November 2018}}

The two extant 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.{{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}}{{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|url-access=subscription }}

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Classification of the Cycadophyta to the rank of family.

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

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

• 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){{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 }}
• ?Anthrophyopsis Late Triassic, worldwide (leaf form genus, possibly a pteridospermatophyte){{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 }}
• Apoldia Triassic-Jurassic, Europe
• Archaeocycas Early Permian, Texas (leaf with sporophylls)
• Aricycas Late Triassic, Arizona (leaf form genus)
• 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 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){{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 }}
• Mesosingeria, Jurassic to Early Cretaceous, Antarctica & Argentina (leaf form genus)
• Michelilloa, Late Triassic, Argentina (stem)
• ?Nikania, Early Cretaceous, Russia (leaf fragments)
• ?Nilssonia, Middle Permian to Late Cretaceous, worldwide (leaf form genus) (possibly not a cycad){{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}}
• ?Nilssoniocladus, Early to Late Cretaceous, United States & Russia (stems, likely associated with Nilssonia, possibly deciduous){{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 }}
• 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){{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 }}
• 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 marattialean ferns)

File:Bowenia spectabilis.JPG : plant with single frond in the Daintree rainforest, north-east Queensland]]

File:Cycad cone.jpg]]

The oldest probable cycad foliage is known from the latest Carboniferous-Early Permian of South Korea and China, such as Crossozamia. Unambiguous fossils of cycads are known from the Early-Middle Permian onwards.{{Cite journal |last1=Spiekermann |first1=Rafael |last2=Jasper |first2=André |last3=Siegloch |first3=Anelise Marta |last4=Guerra-Sommer |first4=Margot |last5=Uhl |first5=Dieter |date=June 2021 |title=Not a lycopsid but a cycad-like plant: Iratinia australis gen. nov. et sp. nov. from the Irati Formation, Kungurian of the Paraná Basin, Brazil |journal=Review of Palaeobotany and Palynology |language=en |volume=289 |pages=104415 |doi=10.1016/j.revpalbo.2021.104415 |bibcode=2021RPaPa.28904415S |s2cid=233860955}} Cycads were generally uncommon during the Permian.{{Cite journal |last=Gomankov |first=A. V. |date=June 2022 |title=Cycads in the Permian of thе Subangara Region |journal=Paleontological Journal |language=en |volume=56 |issue=3 |pages=317–326 |doi=10.1134/S0031030122030066 |bibcode=2022PalJ...56..317G |s2cid=249627815 |issn=0031-0301}} The two living cycad families are thought to have split from each other sometime between the Jurassic and Carboniferous.{{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 |issn=0028-646X|doi-access=free |pmc=10953041 |bibcode=2023NewPh.240.1616C }} Cycads are thought to have reached their apex of diversity during the Mesozoic.{{Cite journal |last1=Coiro |first1=Mario |last2=Seyfullah |first2=Leyla Jean |date=2024-03-14 |title=Disparity of cycad leaves dispels the living fossil metaphor |journal=Communications Biology |language=en |volume=7 |issue=1 |page=328 |doi=10.1038/s42003-024-06024-9 |issn=2399-3642 |pmc=10940627 |pmid=38485767}} Although the Mesozoic is sometimes called the "Age of Cycads," some other groups of distantly related extinct seed plants with similar foliage, such as Bennettitales and Nilssoniales were considerably more abundant than cycads during the Mesozoic, with true cycads being minor components of Mesozoic vegetation.{{Cite journal |last1=Coiro |first1=Mario |last2=Pott |first2=Christian |date=December 2017 |title=Eobowenia gen. nov. from the Early Cretaceous of Patagonia: indication for an early divergence of Bowenia? |journal=BMC Evolutionary Biology |language=en |volume=17 |issue=1 |pages=97 |doi=10.1186/s12862-017-0943-x |issn=1471-2148 |pmc=5383990 |pmid=28388891 |doi-access=free |bibcode=2017BMCEE..17...97C }} The oldest records of the modern genus Cycas are from the Paleogene of East Asia.{{Cite journal |last1=Liu |first1=Jian |last2=Lindstrom |first2=Anders J |last3=Marler |first3=Thomas E |last4=Gong |first4=Xun |date=2022-01-28 |title=Not that young: combining plastid phylogenomic, plate tectonic and fossil evidence indicates a Palaeogene diversification of Cycadaceae |journal=Annals of Botany |language=en |volume=129 |issue=2 |pages=217–230 |doi=10.1093/aob/mcab118 |doi-access=free |issn=0305-7364 |pmc=8796677 |pmid=34520529}} Fossils assignable to Zamiaceae are known from the Cretaceous, with fossils assignable to living genera of the family known from the Cenozoic.

File:Fossilized cycad New York Botanical Garden.jpg

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

The living cycads are found across much of the subtropical and tropical parts of the world, with a few in temperate regions such as in Australia.Orchard, A.E. & McCarthy, P.M. (eds.) (1998). Flora of Australia 48: 1–766. Australian Government Publishing Service, Canberra. The greatest diversity occurs in South and Central America.{{citation needed|date=July 2015}} They are also found in Mexico, the Antilles, southeastern United States, Australia, Melanesia, Micronesia, Japan, China, Southeast Asia, Bangladesh, India, Sri Lanka, Madagascar, and southern and tropical Africa, where at least 65 species occur. Some can survive in harsh desert or semi-desert climates (xerophytic),{{cite report |title=National Recovery Plan for the MacDonnell Ranges Cycad Macrozamia macdonnellii |publisher=Department of Natural Resources, Environment, The Arts and Sport, Northern Territory |url=http://www.environment.gov.au/system/files/resources/c17de516-c635-4c67-b040-c9db4da380e4/files/macrozamia-macdonnellii.pdf |access-date=16 July 2015}} others in wet rain forest conditions,{{cite book |author1=Bermingham, E. |author2=Dick, C.W. |author3=Moritz, C. |year=2005 |title=Tropical Rainforests: Past, Present, and Future |publisher=University of Chicago Press |isbn=9780226044682 |url=https://books.google.com/books?id=Y3dXZyCCDpEC}} and some in both.{{citation |chapter-url=http://iucnredlist.org/details/42000/0 |title=The IUCN Red List of Threatened Species |chapter=Macrozamia communis}} Some can grow in sand or even on rock, some in oxygen-poor, swampy, bog-like soils rich in organic material.{{Citation needed|date=April 2011}} Some are able to grow in full sun, some in full shade, and some in both.{{Citation needed|date=April 2011}} Some are salt tolerant (halophytes).{{citation needed|date=July 2015}}

Species diversity of the extant cycads peaks at 17˚ 15"N and 28˚ 12"S, with a minor peak at the equator. There is therefore not a latitudinal diversity gradient towards the equator but towards the Tropic of Cancer and the Tropic of Capricorn. However, the peak near the northern tropic is largely due to Cycas in Asia and Zamia in the New World, whereas the peak near the southern tropic is due to Cycas again, and also to the diverse genus Encephalartos in southern and central Africa, and Macrozamia in Australia. Thus, the distribution pattern of cycad species with latitude appears to be an artifact of the geographical isolation of the remaining cycad genera and their species, and perhaps because they are partly xerophytic rather than simply tropical.{{citation needed|date=February 2025}}

Nuts of the Cycas orientis (nyathu) are coveted by the Yolngu in Australia's Arnhem Land as a source of food. They are harvested on their dry season to leach its poison under water overnight before ground into a paste, wrapped under bark and cooked on open fire until done.{{cite book|page=48|isbn=978-1-921953-31-6|publisher=National Museum of Australia Press|title= Midawarr {{!}} Harvest: The Art of Mulkun Wirrpanda and John Wolseley |url=https://www.nma.gov.au/about/publications/midawarr-harvest|year=2017}} Roots of Zamia integrifolia were used by the Seminole and other native peoples to produce Florida arrowroot by a similar process.

In Vanuatu, the cycad is known as namele and is an important symbol of traditional culture. It serves as a powerful taboo sign,{{cite web |author=Dan McGarry |date=Apr 9, 2018 |title=A Princely Title |website=Vanuatu Daily Post |url=http://dailypost.vu/news/a-princely-title/article_3b08dcb8-6286-51f6-bc85-ac5aee546242.html}} and a pair of namele leaves appears on the national flag and coat of arms. Together with the nanggaria plant, another symbol of Vanuatu culture, the namele also gives its name to Nagriamel, an indigenous political movement.

• Fossil Cycad National Monument, now withdrawn, in the U.S. state of South Dakota{{-}}

{{Reflist|25em}}

{{Commons}}

• {{cite web |url=http://palm-trees.org/ |title=Palm Trees, Small Palms, Cycads, Bromeliads and tropical plants |archive-url=https://web.archive.org/web/20140520003137/http://palm-trees.org/ |archive-date=2014-05-20}} Site with thousands of large, high quality photos of cycads and associated flora. Includes information on habitat and cultivation. (Site is dead.)
• {{cite web |title=The Cycad Pages |publisher=Royal Botanic Gardens Sydney |url= http://plantnet.rbgsyd.nsw.gov.au/PlantNet/cycad/index.html |url-status=dead |archive-date=29 March 2021 |archive-url=https://web.archive.org/web/20210329132148/https://plantnet.rbgsyd.nsw.gov.au/PlantNet/cycad/index.html}}
• {{cite web |url=http://www.conifers.org/zz/cycadales.htm |title=Gymnosperm Database: Cycads |archive-url=https://web.archive.org/web/20100810215325/http://www.conifers.org/zz/cycadales.htm |archive-date=2010-08-10}}
• {{cite web |title=Fairchild Tropical Botanic Garden |url=http://www.fairchildgarden.org/horticulture/n_collections.html |archive-url=https://web.archive.org/web/20150223092247/http://www.fairchildgarden.org/horticulture/n_collections.html |archive-date=2015-02-23}} One of the largest collections of cycads in the world in Florida, U.S.A.
• {{cite web |title=Main Page |url=http://www.pacsoa.org.au/ |publisher=Palm and Cycad Societies of Australia (PACSOA) |access-date=2023-06-18}}
• {{cite web |title=Welcome |url=http://cycadsociety.org/ |publisher=The Cycad Society of South Africa |access-date=2023-06-18}}
• {{cite web |author=David Dalton |date=1997 |title=Part I. The range of organisms that can fix nitrogen |website=Nitrogen Fixation |url=http://academic.reed.edu/biology/Nitrogen/Nfix1.html |access-date=2023-06-18}} Cycad nitrogen fixation
• {{cite web |title=Cycad toxicity |website=The Cycad Pages |publisher=Royal Botanic Gardens Sydney |url=http://plantnet.rbgsyd.nsw.gov.au/PlantNet/cycad/toxic.html |url-status=dead |archive-date=2020-07-17 |archive-url=https://web.archive.org/web/20200717151457/http://plantnet.rbgsyd.nsw.gov.au/PlantNet/cycad/toxic.html}}
• {{cite web |author=Lauren Kessler |date=Aug 28, 2005 |url=https://www.nytimes.com/2005/08/28/magazine/the-cult-of-the-cycads.html |url-status=live |archive-url=https://web.archive.org/web/20220604003638/https://www.nytimes.com/2005/08/28/magazine/the-cult-of-the-cycads.html |archive-date=2022-06-04 |title=The Cult of the Cycads |work=The New York Times Magazine}} Magazine article on cycad collectorship and cycad smuggling.

{{Plant classification}}

{{Nuts}}

{{Life on Earth}}

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Category:Dioecious plants

Category:Cisuralian first appearances

Category:Extant Permian first appearances