Cycas

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Cycas
Temporal range: Paleogene–Recent
Big Cycas.jpg
A large cycas under development
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Gymnospermae
Division: Cycadophyta
Class: Cycadopsida
Order: Cycadales
Suborder: Cycadineae
Family: Cycadaceae
Pers. [1]
Genus: Cycas
L. [2]
Type species
C. circinalis [2]
L. [2]
Repartitions des Cycas.png
Synonyms [3]
  • DyerocycasNakai
  • Epicycasde Laub.
  • Todda-panaAdans.

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. [4] [5]

Contents

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. [6] [7] [8]

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. [8] [9] [10]

As with other cycads in general, Cycas species may be popularly called 'living fossils', representing the surviving decedents of an ancient lineage of seed-bearing plants that were known to exist in the dinosaur era. Despite their ancient roots, 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. [8]

Range

The genus Cycas is native to parts of Asia, eastern Africa and Oceania. [8] Cycas has the widest distribution of any genus of cycad. [11]

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. [8] [9]

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). [7] 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. [7] [8]

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. [8] [12]

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. [7] [8] [13] At least 7 Cycas species are found in Papua New Guinea, some of which are also found in parts of neighbouring Indonesia. [7] In the broader region, Cycas seemannii is found in Melanesia and western Polynesia and Cycas micronesica is found across Micronesia. [8] [14] [15]

Globally, some Cycas species are considered to have 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. [8] [16]

Evolution

Cycas sp. Cycus tici.jpg
Cycas sp.

Cycas (and the Cycadaceae family) is considered as being an early offshoot from the rest of the cycads and originated in the ancient landmass of Laurasia with Cycas fossils known from the Eocene deposits (38–54 MYA) of China and Japan. [17] [18] Estimates of the timing of the split ranging from the Jurassic [19] to the Carboniferous. [20] 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. [8]

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. [21] 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. [22]

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. [20] The earliest fossils assignable to Cycas are known from the Paleogene of East Asia, such as Cycas fushunensis from the Eocene of Northeast China, with East Asia likely representing the ancestral homeland of the genus. [23]

Morphology

Bark of Cycas rumphii Rumphii1562.jpg
Bark of Cycas rumphii

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.

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.[ clarification needed ] 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.

Reproduction

A male cone of Cycas circinalis Cycas male cone.jpg
A male cone of Cycas circinalis
Cycas native to Odisha
Cycas nayagarhensis Singh Radha Khuraijam.JPG
Cycas nayagarhensis male cone
Cycas orixensis Singh Khuraijam.JPG
Cycas orixensis male cone

Cycas take about 10 years to reach sexual maturity, after years of exclusive vegetative growth, which occurs by bulbils arising at the base of the trunk.[ citation needed ]

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. [24] Cycas rumphii and Cycas pectinata have the most widespread distribution.

Phylogeny

Cycas media megasporophylls with nearly-mature seeds on a wild plant in north Queensland, Australia Cycas media megasporophylls.jpg
Cycas media megasporophylls with nearly-mature seeds on a wild plant in north Queensland, Australia
Grove of Cycas media in north Queensland Cycas media.JPG
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 Cycas platyphylla with new flush of fronds.JPG
Cycas platyphylla in north Queensland with new flush of fronds during the rainy season, still with glaucous bloom
Phylogeny of Cycas [25] [26]
section

C. micholitzii Dyer

Stangerioides
(Pectinata)

C. multipinnata Chen & Yang

C. pectinata Buchanan-Hamilton

C. thouarsii Brown ex Gaudichaud-Beaupré

(Panzhihuaenses)
section

C. revoluta Thunberg (Sago palm)

C. taitungensis Shen et al.

Asiorientales
section

C. tropophylla Hill & Lôc

C. ferruginea Wei

C. curranii (Schuster) Hill

C. debaoensis Zhong & Chen

C. brachycantha Hill, Nguyên & Lôc

C. immersa Craib

Panzhihuaenses
(Cycas)

C. bifida (Dyer) Hill

C. szechuanensis Cheng & Fu

section
subsection

C. wadei Merrill

Wadeanae
subsection
Taiwanianosae
Wadeanae
section
subsection
Cycas
subsection

C. pschannae Srivastava & Singh

C. edentata de Laubenfels

C. nitida Hill & Lindström

C. rumphii Miquel

Rumphiae
Cycas
section

C. clivicola Hill

subsection

C. siamensis Miquel

C. vespertilio Lindström & Hill

C. riuminiana Porte ex Regel

Indosinenses
subsection

C. macrocarpa Griffith

C. nongnoochiae Hill

C. elongata (Leandri) Wang

C. tansachana Hill & Yang

C. lindstromii Yang, Hill & Nguyên

C. condaoensis Hill & Yang

Lindstroemiae
Indosinenses
section

C. diannanensis Guan & Tao

C. cairnsiana von Mueller

C. petrae Lindström & Hill

C. megacarpa Hill

C. calcicola Maconochie

C. armstrongii Miquel

C. balansae Warburg

C. segmentifida Wang & Deng

C. dolichophylla Hill, Nguyên & Lôc

C. simplicipinna (Smitinand) Hill

C. guizhouensis Lan & Zou

C. chevalieri Leandri

C. maconochiei Chirgwin & Hill

C. arenicola Hill

C. schumanniana Lauterbach

C. aculeata Hill & Nguyên

C. silvestris Hill

C. basaltica Gardner

C. semota Hill

C. orientis Hill

C. canalis Hill

C. hongheensis Yang & Yang ex Wang

C. conferta Chirgwin

C. angulata Brown

C. indica Lindström & Hill (=Cycas swamyi)

C. annaikalensis Rita Singh &Radha

C. beddomei Dyer

C. sphaerica Roxburgh

Endemicae

Other species:

Related Research Articles

<span class="mw-page-title-main">Cycad</span> Division of naked seeded dioecious plants

Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or female. Cycads vary in size from having trunks only a few centimeters to several meters tall. They typically grow very slowly and live very long. Because of their superficial resemblance, they are sometimes mistaken for palms or ferns, but they are not closely related to either group.

<span class="mw-page-title-main">Gymnosperm</span> Clade of non-flowering, naked-seeded vascular plants

The gymnosperms are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes, forming the clade Gymnospermae. The term gymnosperm comes from the composite word in Greek: γυμνόσπερμος, literally meaning 'naked seeds'. The name is based on the unenclosed condition of their seeds. The non-encased condition of their seeds contrasts with the seeds and ovules of flowering plants (angiosperms), which are enclosed within an ovary. Gymnosperm seeds develop either on the surface of scales or leaves, which are often modified to form cones, or on their own as in yew, Torreya, Ginkgo. The life cycle of a gymnosperm involves alternation of generations, with a dominant diploid sporophyte phase, and a reduced haploid gametophyte phase, which is dependent on the sporophytic phase. The term "gymnosperm" is often used in paleobotany to refer to all non-angiosperm seed plants. In that case, to specify the modern monophyletic group of gymnosperms, the term Acrogymnospermae is sometimes used.

<i>Cycas revoluta</i> Species of plant

Cycas revoluta is a species of gymnosperm in the family Cycadaceae, native to southern Japan including the Ryukyu Islands. It is one of several species used for the production of sago, as well as an ornamental plant. The sago cycad can be distinguished by a thick coat of fibers on its trunk. The sago cycad is sometimes mistakenly thought to be a palm, although the only similarity between the two is that they look similar and both produce seeds.

<span class="mw-page-title-main">Sago palm</span> Index of plants with the same common name

Sago palm is a common name for several plants which are used to produce a starchy food known as sago. Sago palms may be "true palms" in the family Arecaceae, or cycads with a palm-like appearance. Sago produced from cycads must be detoxified before consumption. Plants called sago palm include:

A strobilus is a structure present on many land plant species consisting of sporangia-bearing structures densely aggregated along a stem. Strobili are often called cones, but some botanists restrict the use of the term cone to the woody seed strobili of conifers. Strobili are characterized by a central axis surrounded by spirally arranged or decussate structures that may be modified leaves or modified stems.

<i>Cycas beddomei</i> Species of cycad

Cycas beddomei is a species of cycad in the genus Cycas, native to India, where it is confined to a small area of Andhra Pradesh state in the Tirumala Hills in scrubland and brush covered hills.

<i>Cycas bougainvilleana</i> Species of cycad

Cycas bougainvilleana is a species of cycad in the genus Cycas, native to the islands northeast of Papua New Guinea, on New Britain, the Bismarck Archipelago and the Solomon Islands, where it occurs on or near the coast in calcareous coral sand dunes and in adjacent forests.

<i>Cycas circinalis</i> Species of cycad

Cycas circinalis, also known as the queen sago, is a species of cycad known in the wild only from southern India. Cycas circinalis is the only gymnosperm species found among native Sri Lankan flora.

<i>Cycas micronesica</i> Species of cycad

Cycas micronesica is a species of cycad found on the island of Yap in Micronesia, the Marianas islands of Guam and Rota, and The Republic of Palau. It is commonly known as federico nut or fadang in Chamorro. The species, previously lumped with Cycas rumphii and Cycas circinalis, was described in 1994 by Ken Hill. Paleoecological studies have determined that C. micronesica has been present on the island of Guam for about 9,000 years. It is linked with Lytico-Bodig disease, a condition similar to amyotrophic lateral sclerosis (ALS), due to the neurotoxin BMAA found in its seeds, which were a traditional food source on Guam until the 1960s. The neurotoxin is present due to its symbiosis with cyanobacteria.

<i>Cycas pectinata</i> Species of cycad

Cycas pectinata was the fourth species of Cycas to be named; it was described in 1826 by Scottish surgeon and botanist Francis Buchanan-Hamilton from Kamrup, Assam in northeast India. The species is one of the most widespread cycads. It is found in the northeastern part of India, Nepal, Bhutan, northern Burma, southern China (Yunnan), Bangladesh, Burma, Malaysia, Cambodia, northern Thailand, Laos, and Vietnam. Cycas pectinata usually grow at elevation 300 m to 1200 m and in difficult terrains. In China, it grows in dry, open thickets in limestone mountains, red soil in sparse monsoon forests. Cycas pectinata grows up to 40 feet (12 m) tall and has very large, ovoid male cones. The tallest Cycas pectinata is a female plant in North Kamrup, Assam which measures 52.8 feet (16.1 m). The tree is the world's tallest Cycas plant. In Northeast India, the species is under severe threat due to clearing of forest and overcollection of male cones for preparation of traditional medicines. The species is listed in CITES Appendix II and IUCN Redlist.

<i>Cycas rumphii</i> Species of plant

Cycas rumphii, commonly known as queen sago or the queen sago palm, is a dioecious gymnosperm, a species of cycad in the genus Cycas native to Indonesia, New Guinea and Christmas Island. Although palm-like in appearance, it is not a palm.

<i>Cycas thouarsii</i> Species of evergreen plant

Cycas thouarsii, the Madagascar cycad, is an evergreen arborescent cycad in the genus Cycas. It is named after the French botanist Louis-Marie Aubert du Petit-Thouars (1758—1831).

<i>Cycas multipinnata</i> Species of cycad

Cycas multipinnata, common name Royal Sago, is a species of cycad or Sago Palm in southwestern China and northern Vietnam. It is noteworthy for three things: First it is one of the tuberous species which some taxonomists segregate as the genus Epicycas. Secondly, it has the longest leaf stalks (petioles) of any Gymnosperm; up to 11.5 feet. Cultivated plants have had petioles as long as thirteen feet. The total length of the bipinnate frond can be up to 23 feet seven meters) The ultimate pinnules are Y-shaped. Thirdly, this very conspicuous plant escaped notice until 1994. Among Gymnosperms, these fronds are exceeded in mass only by Encephalartos laurentianus.

<i>Cycas seemannii</i> Species of plant in the family Cycadaceae

Cycas seemannii is a species of cycad found in Fiji, Vanuatu, Tonga, and New Caledonia.

<i>Cycas riuminiana</i> Species of plant

Cycas riuminiana, commonly known as the Arayat pitogo or simply pitogo, is a species of cycad endemic to Luzon, Philippines. It is also locally known as bayit in Tagalog and sawang in Ilocano, among other names.

<i>Cycas zambalensis</i> Species of cycad

Cycas zambalensis is a species of cycad endemic to Luzon, Philippines.

Cycas sancti-lasallei is a recently described species of cycad endemic to Mindanao, Philippines. It is found in the Cugman River watershed in Cagayan de Oro, Misamis Oriental, Philippines.

<i>Cycas indica</i> Species of cycad

Cycas indica is a species of cycad endemic to India. The species grows in the dry plains of Karnataka and is known for its branching habit. A species Cycas swamyi also considered as a variety of Cycas circinalis is considered as a synonym of this species.

<i>Ctenis</i> Extinct genus of cycads

Ctenis is a genus of fossil foliage attributable to the Cycadales, being one of the most common genera of cycad fossil leaves in the Mesozoic.

References

  1. ↑ Kramer, K.U.; Green, P.S., eds. (1990). Pteridophytes and Gymnosperms (PDF). The families and genera of vascular plants. Vol. 1. Assisted by E. Götz (illustrations). Berlin: Springer-Verlag. p. 370. ISBN   978-3-540-51794-8.
  2. 1 2 3 Hill, Ken; Leonie Stanberg; Dennis Stevenson. "The Cycad Pages". Genus Cycas. Royal Botanic Gardens Sydney. Archived from the original on 2021-03-01. Retrieved 6 September 2013.
  3. ↑ "Cycas L." Plants of the World Online . Royal Botanic Gardens, Kew . Retrieved 28 March 2023.
  4. ↑ Linnaeus, Carl (1753). Palmae Pennatifoliae. Cycas [Cycas circinalis protologue]. pp. Sp. Pl. 2 : 1188.
  5. ↑ Type Location(s): LT:t. 19, in Rheede, Hort. Malab, 3 (1682) Cycas circinalis at The World List of Cycads (cycadlist.org)
  6. ↑ 119 accepted species, with 6 infraspecific taxa, as of April 21, 2024.
  7. 1 2 3 4 5 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 IUCN/SSC Cycad Specialist Group (CSG). The online edition is hosted and sponsored by 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.
  8. 1 2 3 4 5 6 7 8 9 10 11 Donaldson, J.S.; Dehgan, B.; Vovides, A.P.; Tang, W. (2003). "Cycads in trade and sustainable use of cycad populations" (PDF). Cycads Status Survey and Conservation Action Plan. IUCN The World Conservation Union Gland, Switzerland.
  9. 1 2 "Cycas revoluta". cycadlist.org. Retrieved 2024-04-21.
  10. ↑ Marler, Thomas E.; Moore, Aubrey (2010-05-01). "Cryptic Scale Infestations on Cycas revoluta Facilitate Scale Invasions". HortScience. 45 (5): 837–839. doi:10.21273/HORTSCI.45.5.837. ISSN   0018-5345.
  11. ↑ 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: cabidigitallibrary.org
  12. ↑ "Cycas thouarsii". cycadlist.org. Retrieved 2024-04-21.
  13. ↑ "Cycas megacarpa". cycadlist.org. Retrieved 2024-04-21.
  14. ↑ "Cycas seemannii". cycadlist.org. Retrieved 2024-04-21.
  15. ↑ "Cycas micronesica". cycadlist.org. Retrieved 2024-04-21.
  16. ↑ Siyue Xiao, Yunheng Ji, Jian Liu, Xun Gong. Genetic characterization of the entire range of Cycas panzhihuaensis (Cycadaceae). Plant Diversity, 2020, № 1, p. 7-18. Elsevier BV. Available online via ScienceDirect
  17. ↑ Yokoyama, M. 1911. Some Tertiary fossils from the Miike coal fields. Journal of the Colloqium of Science, Tokyo University, 27, 1–12.
  18. ↑ Liu, Y.S., Zhou, Z.Y. and Li, H.M. 1991. First discovery of Cycas fossil leaf in northeast China. Science Bulletin, 22, 1758–1759.
  19. ↑ Nagalingum, N. S.; Marshall, C. R.; Quental, T. B.; Rai, H. S.; Little, D. P.; Mathews, S. (2011-11-11). "Recent Synchronous Radiation of a Living Fossil". Science. 334 (6057): 796–799. Bibcode:2011Sci...334..796N. doi:10.1126/science.1209926. ISSN   0036-8075. PMID   22021670. S2CID   206535984.
  20. 1 2 Coiro, Mario; Allio, Rémi; Mazet, Nathan; Seyfullah, Leyla J.; Condamine, Fabien L. (2023-06-11). "Reconciling fossils with phylogenies reveals the origin and macroevolutionary processes explaining the global cycad biodiversity". New Phytologist. 240 (4): 1616–1635. doi:10.1111/nph.19010. ISSN   0028-646X. PMC   10953041 . PMID   37302411. S2CID   259137975.
  21. ↑ Spencer, Alan R. T.; Garwood, Russell J.; Rees, Andrew R.; Raine, Robert J.; Rothwell, Gar W.; Hollingworth, Neville T. J.; Hilton, Jason (2017-08-28). "New insights into Mesozoic cycad evolution: an exploration of anatomically preserved Cycadaceae seeds from the Jurassic Oxford Clay biota". PeerJ. 5: e3723. doi: 10.7717/peerj.3723 . ISSN   2167-8359. PMC   5578371 . PMID   28875075.
  22. ↑ Rothwell, Gar W.; Stockey, Ruth A.; Stevenson, Dennis W.; Zumajo-Cardona, Cecilia (2022-10-01). "Large Permineralized Seeds in the Jurassic of Haida Gwaii, Western Canada: Exploring the Mode and Tempo of Cycad Evolution". International Journal of Plant Sciences. 183 (8): 674–690. doi:10.1086/721710. ISSN   1058-5893. S2CID   251947260.
  23. ↑ Liu, Jian; Lindstrom, Anders J; Marler, Thomas E; Gong, Xun (2022-01-28). "Not that young: combining plastid phylogenomic, plate tectonic and fossil evidence indicates a Palaeogene diversification of Cycadaceae". Annals of Botany. 129 (2): 217–230. doi:10.1093/aob/mcab118. ISSN   0305-7364. PMC   8796677 . PMID   34520529.
  24. ↑ "Appendices I, II and III". Convention on International Trade in Endangered Species of Wild Fauna and Flora. 21 May 2023. Retrieved 22 August 2023.
  25. ↑ Stull, Gregory W.; Qu, Xiao-Jian; Parins-Fukuchi, Caroline; Yang, Ying-Ying; Yang, Jun-Bo; Yang, Zhi-Yun; Hu, Yi; Ma, Hong; Soltis, Pamela S.; Soltis, Douglas E.; Li, De-Zhu; Smith, Stephen A.; Yi, Ting-Shuang; et al. (2021). "Gene duplications and phylogenomic conflict underlie major pulses of phenotypic evolution in gymnosperms". Nature Plants. 7 (8): 1015–1025. bioRxiv   10.1101/2021.03.13.435279 . doi:10.1038/s41477-021-00964-4. PMID   34282286. S2CID   232282918.
  26. ↑ Stull, Gregory W.; et al. (2021). "main.dated.supermatrix.tree.T9.tre". Figshare. doi:10.6084/m9.figshare.14547354.v1.{{cite journal}}: Cite journal requires |journal= (help)
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