''Cycas'' is a genus of

cycad Cycads are seed plants that typically have a stout and woody (ligneous) trunk (botany), trunk with a crown (botany), crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants o ...

, 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 In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

of the genus. As of April 2024, there are 119 accepted

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

within the genus ''Cycas'', all of which are native to

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

, Oceania, and eastern Africa and the Indian ocean region, with the largest number of species native to Australia, China and Vietnam.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 th
IUCN/SSC Cycad Specialist Group (CSG)
The online edition is hosted and sponsored b
Montgomery Botanical Center
Calonje M, Stevenson DW, Osborne R. The World List of Cycads, online edition nternet 2013-2024. ited 2024 Apr 21 Available from
http://www.cycadlist.org
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. 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

The genus ''Cycas'' is native to parts of

, eastern

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

and

Oceania Oceania ( , ) is a region, geographical region including Australasia, Melanesia, Micronesia, and Polynesia. Outside of the English-speaking world, Oceania is generally considered a continent, while Mainland Australia is regarded as its co ...

. ''Cycas'' has the widest distribution of any genus of cycad. In Asia, ''Cycas'' (and therefore, the family Cycadaceae) represent the only cycads native to Asia. Within Asia, ''Cycas'' species are native from

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

and

Sri Lanka Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka, also known historically as Ceylon, is an island country in South Asia. It lies in the Indian Ocean, southwest of the Bay of Bengal, separated from the Indian subcontinent, ...

in the west, through

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

in the north east and through south east Asia (including the

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

) to

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

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 Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and has ...

Laos Laos, officially the Lao People's Democratic Republic (LPDR), is the only landlocked country in Southeast Asia. It is bordered by Myanmar and China to the northwest, Vietnam to the east, Cambodia to the southeast, and Thailand to the west and ...

, and

Cambodia Cambodia, officially the Kingdom of Cambodia, is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. It is bordered by Thailand to the northwest, Laos to the north, and Vietnam to the east, and has a coastline ...

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 Mozambique, officially the Republic of Mozambique, is a country located in Southeast Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west, and Eswatini and South Afr ...

Tanzania Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...

, and

Kenya Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...

in mainland Africa, extending to the

Seychelles Seychelles (, ; ), officially the Republic of Seychelles (; Seychellois Creole: ), is an island country and archipelagic state consisting of 155 islands (as per the Constitution) in the Indian Ocean. Its capital and largest city, Victoria, ...

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

and

Comoros The Comoros, officially the Union of the Comoros, is an archipelagic country made up of three islands in Southeastern Africa, located at the northern end of the Mozambique Channel in the Indian Ocean. Its capital and largest city is Moroni, ...

islands in the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...

. In Oceania, ''Cycas'' species are native to

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

Papua New Guinea Papua New Guinea, officially the Independent State of Papua New Guinea, is an island country in Oceania that comprises the eastern half of the island of New Guinea and offshore islands in Melanesia, a region of the southwestern Pacific Ocean n ...

, and the island nations of the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

region, but are absent from

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

. 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 Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

. At least 7 ''Cycas'' species are found in

, some of which are also found in parts of neighbouring

. In the broader region, '' Cycas seemannii'' is found in

Melanesia Melanesia (, ) is a subregion of Oceania in the southwestern Pacific Ocean. It extends from New Guinea in the west to the Fiji Islands in the east, and includes the Arafura Sea. The region includes the four independent countries of Fiji, Vanu ...

and western

Polynesia Polynesia ( , ) is a subregion of Oceania, made up of more than 1,000 islands scattered over the central and southern Pacific Ocean. The indigenous people who inhabit the islands of Polynesia are called Polynesians. They have many things in ...

and '' Cycas micronesica'' is found across

Micronesia Micronesia (, ) is a subregion of Oceania, consisting of approximately 2,000 small islands in the Northwestern Pacific Ocean. It has a close shared cultural history with three other island regions: Maritime Southeast Asia to the west, Poly ...

. 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.

Evolution

''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 The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

to the

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

. The earliest

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s assignable to ''Cycas'' are known from the

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

of East Asia, such as ''Cycas fushunensis'' from the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

(around 47.5 million years ago) of

Northeast China Northeast China () is a geographical region of China, consisting officially of three provinces Liaoning, Jilin and Heilongjiang. The heartland of the region is the Northeast China Plain, the largest plain in China with an area of over . The regi ...

with East Asia likely representing the ancestral homeland of the genus. 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. A later study suggested that these seeds could not be assigned to the

stem-group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...

of ''Cycas'' with confidence due to lacking the double vascular system that characterises the seeds of all living cycads. 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 Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...

analysis.

Conservation status

''Cycas'' species are threatened worldwide and almost all the species are listed in the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological ...

. '' 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. '' Cycas rumphii'' and '' Cycas pectinata'' have the most widespread distribution.

Phylogeny

Cycas platyphylla with new flush of fronds

Other species: *'' Cycas aenigma'' K.D.Hill & A.Lindstr. *'' Cycas apoa'' K.D.Hill *'' Cycas arnhemica'' K.D.Hill *'' Cycas badensis'' K.D.Hill *'' Cycas bglswamyi'' Pant ex Agrawal, Akhtar & R.C.Srivast. *'' Cycas brunnea'' K.D.Hill *'' Cycas campestris'' K.D.Hill *'' Cycas candida'' K.D.Hill *'' Cycas cantafolia'' Jutta, K.L.Chew & Saw *'' Cycas changjiangensis'' N.Liu *'' Cycas chenii'' X.Gong & Wei Zhou *'' Cycas collina'' K.D.Hill, H.T.Nguyen & P.K.Lôc *'' Cycas cupida'' P.I.Forst. *'' Cycas darshii'' R.C.Srivast. & Jana *'' Cycas desolata'' P.I.Forst. *'' Cycas dharmrajii'' L.J.Singh *'' Cycas distans'' P.I.Forst. & B.Gray *'' Cycas divyadarshanii'' Khuraijam & Rita Singh *'' Cycas elephantipes'' A.Lindstr. & K.D.Hill *'' Cycas falcata'' K.D.Hill *'' Cycas flabellata'' Agoo, Madulid & J.R.Callado *'' Cycas fugax'' K.D.Hill, H.T.Nguyen & P.K.Lôc *'' Cycas furfuracea'' W.Fitzg. *'' Cycas glauca'' Miq. *'' Cycas hoabinhensis'' Lôc & H.T.Nguyen *'' Cycas inermis'' Oudem. *'' Cycas javana'' (Miq.) de Laub. *'' Cycas lacrimans'' A.Lindstr. & K.D.Hill *'' Cycas lane-poolei'' C.A.Gardner *'' Cycas laotica'' T.H.Nguyên & K.S.Nguyen *'' Cycas litoralis'' K.D.Hill *'' Cycas mindanaensis'' Agoo, Madulid & J.R.Callado *'' Cycas miquelii'' Warb. *'' Cycas montana'' A.Lindstr. & K.D.Hill *'' Cycas nayagarhensis'' Rita Singh, P.Radha & Khuraijam *'' Cycas nathorstii'' J.Schust. *'' Cycas orixensis'' (Haines) Rita Singh & Khuraijam *'' Cycas pachypoda'' K.D.Hill *'' Cycas panzhihuaensis'' Zhou & S.Y.Yang *'' Cycas papuana'' F.Muell. *'' Cycas pectinata'' *'' Cycas pranburiensis'' S.L.Yang et al. *'' Cycas pruinosa'' Maconochie *'' Cycas sainathii'' R.C.Srivast. *'' Cycas sancti-lasallei'' Agoo & Madulid *'' Cycas saxatilis'' K.D.Hill & A.Lindstr. *'' Cycas scratchleyana'' F.Muell. *'' Cycas seemannii'' A.Braun *'' Cycas seshachalamensis'' P.V.C.Rao et al. *'' Cycas sexseminifera'' F.N.Wei *'' Cycas shanyaensis'' Fu *'' Cycas sundaica'' Miq. ex A.Lindstr. & K.D.Hill *'' Cycas terryana'' P.I.Forst. *'' Cycas tuckeri'' K.D.Hill *'' Cycas xipholepis'' K.D.Hill *'' Cycas yorkiana'' K.D.Hill *'' Cycas yunnanensis'' Cheng, Fu & Cheng *'' Cycas zambalensis'' Madulid & Agoo *'' Cycas zeylanica'' (J.Schust.) A.Lindstr. & K.D.Hill

References

External links

* *Hill, K.D.(1998–2004) The Cycad Pages, Royal Botanic Gardens Sydney. http://plantnet.rbgsyd.nsw.gov.au/PlantNet/cycad/index.html
Virtual Cycad Encyclopedia
edited by the Palm & Cycad Societies of Florida *David, J. de Laubenfels
Cycas Taxonomy
* * *Singh, R & JS Khuraijam (2013-) Cycads of India. http://www.cycadsofindia.in/ * * *Terrence Walters & Roy Osborne (eds.) (2004), ''Cycad Classification: Concepts and Recommendations'', CABI publishing, Plants described in 1753 Taxa named by Carl Linnaeus {{Improve categories, date=February 2025