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Big Cycas.jpg
A large cycas under development
Scientific classification e
Kingdom: Plantae
Division: Cycadophyta
Class: Cycadopsida
Order: Cycadales
Suborder: Cycadineae
Family: Cycadaceae
Genus: Cycas
Type species
C. circinalis[1]
  • Todda-pana Adans.
  • Dyerocycas Nakai
  • Epicycas de Laub.
  • Eucycas

family synonymy =

  • Cycaceae

Cycas is the type genus and the only genus recognised in the family Cycadaceae. About 113 species are accepted.[4] Cycas circinalis, a species endemic to India was the first cycad species to be described and was the type of the generic name, Cycas. The best-known Cycas species is Cycas revoluta. Cycas is a very ancient genus of trees. The group achieved its maximum diversity in the Jurassic and Cretaceous periods, when it was distributed almost worldwide. At the end of the Cretaceous, when the non-avian dinosaurs became extinct, so did most of the cycas in the Northern Hemisphere.


The genus is native to the Old World, with the species concentrated around the equatorial regions - eastern and southeastern Asia including the Philippines with 10 species (9 of which are endemic), eastern Africa (including Madagascar), northern Australia, Polynesia, and Micronesia. Australia has 26 species, while the Indo-Chinese area has about 30. India has 9 species. The northernmost species (C. revoluta) is found at 31°N in southern Japan. The southernmost (C. megacarpa) is found at 26°S in southeast Queensland. Due to the occurrence of large number of Cycas species in China, Australia and India, those countries are considered as centres of Cycas diversity.[3]

A male cone of Cycas orixensis with unique forked microsporophylls
Bark of Cycas rumphii


Cycus tici

Often considered a living fossil, the earliest fossils of the genus Cycas appear in the Cenozoic although Cycas-like fossils that may belong to Cycadaceae extend well into the Mesozoic. Cycas is not closely related to other genera of cycads, and phylogenetic studies have shown that Cycadaceae is the sister-group to all other extant cycads. 》Cycas is considered as "relic of past" because archegonia is produced from the cells of female gametophyte. 》Even though the seeds of cycas are with two cotyledons they arr not placed in dicots as ovary is absent. 》"In cycas male gamets, female gamets and ovules are largest in the plant kingdom". Eventough the ovules are largest but seeds are not largest.

  • Cycas has few fern characters they are

1. Cercinate vernation 2. Presence of ramenta 3. Top shaped ciliated male gametes.


The plants are dioecious, and the family Cycadaceae is unique among the cycads in not forming seed cones on female plants, but rather a group of leaf-like structures called megasporophylls each with seeds on the lower margins, and pollen cones or strobilus on male individuals.

Cycas media megasporophylls with nearly-mature seeds on a wild plant in north Queensland, Australia
Grove of Cycas media in north Queensland
Cycas platyphylla in north Queensland with new flush of fronds during the rainy season, still with glaucous bloom

The caudex is cylindrical, surrounded by the persistent petiole bases. Most species form distinct branched or unbranched trunks but in some species the main trunk can be subterranean with the leaf crown appearing to arise directly from the ground. There are two types of leaves - foliage leaves and scaly leaves. The foliage leaves are pinnate (or more rarely bipinnate) and arranged spirally, with thick and hard keratinose. They are not permanent and fall off leaving back leaf-bases. The leaflets are articulated, have midrib but lack secondary veins. The scaly leaves are persistent, brown in colour and protective in function. Megasporophylls are not gathered in cones. Pollination takes place by air.


The plant takes several years to grow, sexual reproduction takes place after 10 years of exclusive vegetative growth which occurs by bulbils arising at the base of the trunk.

A male cone of Cycas circinalis

Conservation status[edit]

Cycas species are threatened worldwide and almost all the species are listed in IUCN Redlist. Cycas beddomei is the only species of the genus Cycas listed in Appendix I of CITES. Cycas rumphii and Cycas pectinata have the most widespread distribution.

List of species[edit]

Cycas aculeata
Cycas aenigma
Cycas angulata
Cycas annaikalensis
Cycas apoa
Cycas arenicola
Cycas armstrongii
Cycas arnhemica
Cycas badensis
Cycas balansae
Cycas basaltica
Cycas beddomei
Cycas bifida
Cycas bougainvilleana
Cycas brachycantha
Cycas brunnea
Cycas cairnsiana
Cycas calcicola
Cycas campestris
Cycas canalis
Cycas candida
Cycas cantafolia
Cycas chamaoensis
Cycas changjiangensis
Cycas chenii
Cycas chevalieri
Cycas circinalis
Cycas clivicola
Cycas collina
Cycas condaoensis
Cycas conferta
Cycas couttsiana
Cycas cupida
Cycas curranii
Cycas debaoensis
Cycas desolata
Cycas diannanensis
Cycas dolichophylla
Cycas edentata
Cycas elephantipes
Cycas elongata
Cycas falcata
Cycas fairylakea
Cycas ferruginea
Cycas fugax
Cycas furfuracea
Cycas glauca
Cycas guizhouensis
Cycas hainanensis
Cycas hoabinhensis
Cycas hongheensis
Cycas indica
Cycas inermis
Cycas javana
Cycas lacrimans
Cycas lane-poolei
Cycas lindstromii
Cycas litoralis
Cycas maconochiei
Cycas macrocarpa
Cycas media
Cycas megacarpa
Cycas micholitzii
Cycas micronesica
Cycas montana
Cycas multipinnata
Cycas nathorstii
Cycas nayagarhensis
Cycas nitida
Cycas nongnoochiae
Cycas ophiolitica
Cycas orientis
Cycas orixensis
Cycas pachypoda
Cycas panzhihuaensis
Cycas papuana
Cycas pectinata
Cycas petraea
Cycas platyphylla
Cycas pranburiensis
Cycas pruinosa
Cycas revoluta (Sago palm)
Cycas riuminiana
Cycas rumphiiMiq.
Cycas sancti-lasallei
Cycas sainathii
Cycas saxatilis
Cycas schumanniana
Cycas scratchleyana
Cycas seemannii A.Braun
Cycas segmentifida
Cycas semota
Cycas sexseminifera
Cycas shanyaensis
Cycas siamensis
Cycas silvestris
Cycas simplicipinna
Cycas sphaerica
Cycas sundaica
Cycas swamyi
Cycas szechuanensis
Cycas taitungensis
Cycas taiwaniana
Cycas tanqingii
Cycas tansachana
Cycas thouarsii
Cycas tropophylla
Cycas tuckeri
Cycas vespertilio
Cycas wadei
Cycas xipholepis
Cycas yorkiana
Cycas yunnanensis
Cycas zambalensis
Cycas zeylanica

References and external links[edit]

  1. ^ a b c Hill, Ken; Leonie Stanberg; Dennis Stevenson. "The Cycad Pages". Genus Cycas. Royal Botanic Gardens Sydney. Retrieved 6 September 2013.
  2. ^ Kramer, K.U.; (illustrations), P.S. Green; assisted by E. Götz (1990). Kramer, K.U.; Green, P.S, eds. Pteridophytes and Gymnosperms. Berlin: Springer-Verlag. p. 370. ISBN 978-3-540-51794-8.CS1 maint: Uses authors parameter (link)
  3. ^ a b Kew World Checklist of Selected Plant Families
  4. ^ The World List of Cycads