Cycas revoluta

Cycas revoluta (Sotetsu [Japanese ソテツ], sago palm, king sago, sago cycad, Japanese sago palm), 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.

Japanese sago palm
Cycas inflorescence
Leaves and male cone of Cycas revoluta
Scientific classification
Kingdom: Plantae
Division: Cycadophyta
Class: Cycadopsida
Order: Cycadales
Family: Cycadaceae
Genus: Cycas
C. revoluta
Binomial name
Cycas revoluta


Cycads' only relation to the true palms (Arecaceae) is that both are seed plants. The Latin specific epithet revoluta means "curled back",[2] in reference to the leaves. This is also called Kungi (comb) Palm in Punjabi speaking areas.[3]


This very symmetrical plant supports a crown of shiny, dark green leaves on a thick shaggy trunk that is typically about 20 cm (7.9 in) in diameter, sometimes wider. The trunk is very low to subterranean in young plants, but lengthens above ground with age. It can grow into very old specimens with 6–7 m (over 20 feet) of trunk; however, the plant is very slow-growing and requires about 50–100 years to achieve this height. Trunks can branch several times, thus producing multiple heads of leaves.[4]

Cycas revoluta

The leaves are a deep semiglossy green and about 50–150 cm (20–59 in) long when the plants are of a reproductive age. They grow out into a feather-like rosette to 1 m (3.3 ft) in diameter. The crowded, stiff, narrow leaflets are 8–18 cm (3.1–7.1 in) long and have strongly recurved or revolute edges. The basal leaflets become more like spines. The petiole or stems of the sago cycad are 6–10 cm (2.4–3.9 in) long and have small protective barbs.

Roots are called coralloid with an Anabaena symbiosis allowing nitrogen fixation.[5] Tannins-rich cells are found on either side of the algal layer to resist the algal invasion.

As with other cycads, it is dioecious, with the males bearing pollen cones (strobilus) and the females bearing groups of megasporophylls. Pollination can be done naturally by insects or artificially.

Cultivation and uses

Propagation of Cycas revoluta is either by seed or clonally by removal of basal offsets. It is one of the most widely cultivated cycads, grown outdoors in warm temperate and subtropical regions, or under glass in colder areas. It grows best in sandy, well-drained soil, preferably with some organic matter. It needs good drainage or it will rot. It is fairly drought-tolerant and grows well in full sun or outdoor shade, but needs bright light when grown indoors. The leaves can bleach somewhat if moved from indoors to full sun outdoors.

Snow on Cycas revoluta
Cycas revoluta also called Kangi Palm covered with snow.

Of all the cycads, C. revoluta is the most popular in cultivation. It is seen in almost all botanical gardens, in both temperate and tropical locations. In many areas of the world, it is heavily promoted commercially as a landscape plant. It is also quite popular as a bonsai plant. First described in the late 18th century, it is tolerant of mild to somewhat cold temperatures, provided the ground is dry. Frost damage can occur at temperatures below −10 °C (14 °F). Healthy specimens have been grown with little protection as far north as St. Louis, Missouri, and New York, New York, both in USDA zone 7b. C. revoluta usually defoliates in winter in this temperate climate, but will usually flush (grow) several new leaves by spring.

This plant has gained the Royal Horticultural Society's Award of Garden Merit[6] (confirmed 2017).[7]


The pith contains edible starch, and is used for making sago. Before use, the starch must be carefully washed to leach out toxins contained in the pith. Extracting edible starch from the sago cycad requires special care due to the poisonous nature of cycads. Cycad sago is used for many of the same purposes as palm sago. Sago is extracted from the sago cycad by cutting the pith from the stem, root and seeds of the cycads, grinding the pith to a coarse flour and then washing it carefully and repeatedly to leach out the natural toxins. The starchy residue is then dried and cooked, producing a starch similar to palm sago/sabudana. The cycad seed contains cycasin toxin and should not be eaten as it is possible for cycasin toxin to survive the most vigorous of repeated washings. Cycasin toxin can cause ALS, Parkinson's, prostate cancer and fibrolamellar hepatocellular carcinoma.

Aulacaspis yasumatsui is a scale insect feeding on C. revoluta, and unchecked is able to destroy the plant.[8]


Cycas revoluta.Düsseldorf
Example of a full-grown tree

The hydro-alcoholic extract of leaves of C. revoluta shows the presence of alkaloids, steroids and tannins while the chloroform extract shows the presence of saponins, tannins and sugars.[9] Leaflets also contain biflavonoids.[10] Estragole is the primary volatile compound emitted from the male and female cones of C. revoluta.[11]


Cycad sago is extremely poisonous to animals (including humans) if ingested. Pets are at particular risk, since they seem to find the plant very palatable.[12] Clinical symptoms of ingestion will develop within 12 hours, and may include vomiting, diarrhea, weakness, seizures, and liver failure or hepatotoxicity characterized by icterus, cirrhosis, and ascites. The pet may appear bruised, have nose bleeds (epistaxis), melena (blood in the stool), hematochezia (bloody straining), and hemarthrosis (blood in the joints).[13] The ASPCA Animal Poison Control Center estimates a fatality rate of 50 to 75% when ingestion of the sago palm is involved. If any quantity of the plant is ingested, a poison control center or doctor should be contacted immediately. Effects of ingestion can include permanent internal damage and death.

All parts of the plant are toxic; however, the seeds contain the highest level of the toxin cycasin. Cycasin causes gastrointestinal irritation, and in high enough doses, leads to liver failure.[14] Other toxins include Beta-methylamino L-alanine, a neurotoxic amino acid, and an unidentified toxin which has been observed to cause hindlimb paralysis in cattle.[15]

Sago palm in Mohali
Sago palm in Mohali


Cycas revoluta female cone01

Female reproductive structure

Cycas revoluta01
Cycas revoluta02
Cycas revoluta004
Cycas revoluta new leafs

New leaves

Sago Palm
Cycas revoluta1328A
Cycas Sago.palm.arp.750pix

Young plant

Cycas revoluta seeds


Cycas revoluta seedling



Cycas revoluta

Funchal Botanical garden - Cycas revoluta
Funchal, Monte - Cycas revoluta IMG 1970
Funchal, Monte - Cycas revoluta IMG 1907
KG Cycas revoluta
Branching Cycas revoluta

A sixteen year-old two-branched specimen

Cycas revoluta MHNT.BOT.2018.28.17

Cycas revoluta - MHNT


  1. ^ Hill (2003). "Cycas revoluta". IUCN Red List of Threatened Species. Version 2006. International Union for Conservation of Nature. Retrieved 11 May 2006.
  2. ^ D. Gledhill The Names of Plants, p. 329, at Google Books
  3. ^ Harrison, Lorraine (2012). RHS Latin for gardeners. United Kingdom: Mitchell Beazley. p. 224. ISBN 9781845337315.
  4. ^ Thunberg, Carl Peter. 1782. Verhandelingen uitgegeeven door de hollandse maatschappy der weetenschappen, te Haarlem 20(2): 424, 426–427.
  5. ^ Ultrastructure and phenolic histochemistry of the Cycas revoluta-Anabaena symbiosis. M. Obukowicz, M. Schaller and G.S. Kennedy, New Phytologist, April 1981, Volume 87, Issue 4, pages 751–759, doi:10.1111/j.1469-8137.1981.tb01711.x
  6. ^ "Cycas revoluta". Royal Horticultural Society. Retrieved 22 July 2013.
  7. ^ "AGM Plants - Ornamental" (PDF). Royal Horticultural Society. July 2017. p. 22. Retrieved 24 January 2018.
  8. ^ Aulacaspis yasumatsui (Hemiptera: Sternorrhyncha: Diaspididae), a Scale Insect Pest of Cycads Recently Introduced into Florida. Forrest W. Howard, Avas Hamon, Michael Mclaughlin, Thomas Weissling and Si-lin Yang, The Florida Entomologist, March 1999, Vol. 82, No. 1, pages 14-27 (article)
  9. ^ Leaves Of Cycas revoluta: Potent Antimicrobial And Antioxidant Agent. Manoj K Mourya, Archana Prakash, Ajay Swami, Gautam K Singh and Abhishek Mathur, World Journal of Science and Technology, 2011, Vol 1, No 10, pages 11-20 (article)
  10. ^ Phytochemical Investigation of Cycas circinalis and Cycas revoluta Leaflets: Moderately Active Antibacterial Biflavonoids. Abeer Moawad, Mona Hetta, Jordan K. Zjawiony, Melissa R. Jacob, Mohamed Hifnawy, Jannie P. J. Marais and Daneel Ferreira, Planta Med., 2010, 76(8), pages 796-802, doi:10.1055/s-0029-1240743
  11. ^ Estragole (4-allylanisole) is the primary compound in volatiles emitted from the male and female cones of Cycas revoluta. Hiroshi Azuma and Masumi Kono, Journal of Plant Research, November 2006, Volume 119, Issue 6, pages 671-676, doi:10.1007/s10265-006-0019-2
  12. ^ Suspected cycad (Cycas revoluta) intoxication in dogs, Botha CJ, Naude TW, Swan GE, et al.| J S Afr Vet Assoc | 1991
  13. ^ Muller-Esneault, Susan (2009). "Cycas Revoluta: The Sago Palm, or Cycad Toxicity".
  14. ^ Selected poisonous plant concerns small animals, Knight MW, Dorman DC | Vet Med | 1997 | 92(3):260-272
  15. ^ Toxicology Brief: Cycad toxicosis in dogs, Hany Youssef| Veterinary Medicine | May 1, 2008 | [1]

External links

Amagi, Kagoshima

Amagi (天城町, Amagi-chō) is a town located on Tokunoshima, in Ōshima District, Kagoshima Prefecture, Japan.

As of June 2013, the town has an estimated population of 6,350 and a population density of 79 persons per km². The total area is 80.35 km². The economy of the town is based on sugar cane, beef and seasonal tourism.

Aulacaspis yasumatsui

Aulacaspis yasumatsui, or cycad aulacaspis scale (CAS), is a scale insect species in the genus Aulacaspis that feeds on cycad species such as Cycas revoluta or Dioon purpusii (Purpus' cycad). Other common names include the cycad scale, the sago palm scale, and the Asian cycad scale. This is a serious pest of cycads which can kill its host plant.


Biflavonoids are a type of flavonoids with the general formula scheme (C6-C3-C6)2.


Cycas is the type genus and the only genus recognised in the family Cycadaceae. About 113 species are accepted. 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.

Cycas basaltica

Cycas basaltica is a species of cycad in the genus Cycas, native to Australia, in the far north of Western Australia in the Kimberley region.

The stems grow to 2 m (rarely 4 m) tall and 15–23 cm in diameter, with a swollen base and an enlarged subterranean structure. There are 30 or more leaves in the crown, forming a bowl shaped, inward facing leaf crown, each leaf 80–125 cm long, pinnate, with 140-210 leaflets. Younger plants have spiny petioles, with older specimens losing this trait. The leaflets are covered with a dense layer of silver hairs, angled forward at 70-80°. The basal leaflets are reduced to spines, similar to Cycas revoluta. The taproot is contractile, and tends to pull crown downwards.

The female cones are open, with sporophylls 17–24 cm long, densely red-brown tomentose. Yellowish-brown sarcotesta, glabrous and/or glaucous. The male cones are solitary and erect, narrow conical, 18–24 cm long and 7–9 cm diameter.

Cycas beddomei

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.

Superficially similar to Cycas revoluta, it has erect, solitary stems. There are 20-30 leaves in the crown, each leaf 90 cm long, stiff, lanceolate, pinnate, with 50-100 pairs of leaflets, these 10-17.5 cm long and 3–4 mm wide, and angled forward at 45 degrees; the leaf petiole bears minute spines.

The female cones are open, with sporophylls 15–20 cm long, with pink-brown coloured tomentose down, with two ovules. The cones emerge in November to December, ripening in March to May. The lamina margin is strongly toothed, with an acuminate point. The sarcotesta is yellow to brown. The male cones are solitary, ovoid, 30 cm long and 7.5 cm broad, with an apical spine and rhomboid sporophyll face.

The species is unusual in that it contains a layer of fleshy material between the sarcotesta and the sclerotesta that is thought to aid the seed by providing it with a source of water. As cycad seeds have no dormancy, this would be an important trait in its arid habitat.

It is named after the botanist Richard Henry Beddome.

Cycas circinalis

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.


Cycasin is a carcinogenic and neurotoxic glucoside found in cycads such as Cycas revoluta and Zamia pumila. Symptoms of poisoning include vomiting, diarrhea, weakness, seizures, and hepatoxicity. In metabolic conditions, cycasin is hydrolyzed into glucose and methylazoxymethanol (MAM), the latter of which dissociates into formaldehyde and methyl-diazonium.It induces hepatotoxicity and Zamia staggers, a fatal nervous disease affecting cattle resulting from browsing on the leaves or fruit of cycads.

Eumaeus atala

Eumaeus atala, the Atala or coontie hairstreak, is a small colorful butterfly in the family Lycaenidae. It is found in southeastern Florida, the Bahamas, Cuba, the Cayman Islands, and probably on other Caribbean islands. Its coloration and habits are unique among butterflies within its range.

The Atala is a great example of aposematic (warning) coloration throughout its life cycle. The brightly colored larva or caterpillar feeds on cycads which contain a toxic secondary plant chemical (cycasin) which it retains in its body for life. Birds, lizards, and other animals may attempt to prey on the larva, pupa, and adults, but find them distasteful and learn to avoid these brightly patterned insects. In Florida, the larvae feed on a native cycad, Zamia pumila, commonly called coontie or arrowhead, as well as introduced ornamental cycads. In Cuba, the cycad Cycas revoluta is eaten.

Adult butterflies take flower nectar and sometimes roost in trees. Adults fly through much of the year. The natural habitat is open brushy areas and subtropical hammocks, often in pine woodlands. Many populations now exist in suburban areas with ornamental cycads. Adults keep close to a site with host plants, thus the species forms small colonies. The females, however, may disperse in search of more hosts. The butterfly's flight is slow, unlike the swift, erratic flight of many other Lycaenidae. Like many Lepidoptera, male Atalas have hair-pencils (coremata) on their abdomens used in courtship—the male hovers in front of the female, wafting pheromones exuded from the pencils in her direction. Eggs are laid in clusters of 10-50 on the leaf tips of the host plant. Larvae feed on the leaves. Pupation is usually on the host plant.

The Florida subspecies of this butterfly (Eumaeus atala florida) was at one time believed to have become extinct due to over harvest of its host plant, coontie. It was not collected in Florida from 1937 until 1959. The Atala is now common locally in southeast Florida, rebounding to some extent as it has begun to use ornamental cycads planted in suburban areas. In Palm Springs, Florida, the G-Star School of the Arts has been contributing to the regrowth of the subspecies.The species was originally described by the Cuban zoologist Felipe Poey. He named the butterfly for Atala, the Native American heroine of an 1801 French novella by Chateaubriand, Atala, ou Les Amours de deux sauvages dans le desert.

Kanzen Teruya

Kanzen Teruya (1920–2004) was a physician who contributed much to the Okinawan medical world in postwar days. He reported a mass Cycas revoluta poisoning in people living in Miyakojima Island in 1956. He later became professor at the University of the Ryukyus (1978–1985).

List of cycad species by country

Below is a list of cycad species by ordered by country.

Minamiōsumi, Kagoshima

Minamiōsumi (南大隅町, Minamiōsumi-chō) is a town located in Kimotsuki District, Kagoshima Prefecture, Japan. The town occupies the southern part of the Ōsumi Peninsula and its name literally means "the southern part of Ōsumi."

The town was formed on March 31, 2005 from the merger of the towns of Nejime and Sata, both from Kimotsuki District.

As of April 2017, the town has an estimated population of 9,897. The total area is 213.59 km².

Miyazaki Prefecture

Miyazaki Prefecture (宮崎県, Miyazaki-ken) is a prefecture of Japan on the island of Kyushu. The capital is the city of Miyazaki.

Palm and Cycad Arboretum

The Palm and Cycad Arboretum at the Florida State College at Jacksonville is located on the south campus at 11901 Beach Boulevard, Jacksonville, Florida, United States. This is an outdoor area next to the G building, a large three-story complex in the middle of campus that houses the library and other facilities. There is also a biologically diverse area of larger trees and mid-growth brush in an immediate westerly direction to this area. As the Arboretum is an open area, there are no specific set hours, and its use is free and available to all students and visitors.

Collections include Acoelorraphe wrightii, Allagoptera arenaria, Allagoptera arenaria, Arenga engleri, Braea armataz, Brahea brandegeei, Chamaedorea microspadix, Chamaedorea radicalis, Chamaerops humil, Chamaerops humil, Cycas revoluta, Dioon edule, Dioon spinolusum, Livistona drudei, Livistona mariae, Livistona speciosa, Phoenix reclinata, Phoenix theophrastii, Sabal mauritiiformis, Trithrinax acanthocoma, and Zamia pulila.


Sago is a starch extracted from the spongy centre, or pith, of various tropical palm stems, especially that of Metroxylon sagu. It is a major staple food for the lowland peoples of New Guinea and the Moluccas, where it is called saksak, rabia and sagu. The largest supply of sago comes from Southeast Asia, particularly Indonesia and Malaysia. Large quantities of sago are sent to Europe and North America for cooking purposes. It is traditionally cooked and eaten in various forms, such as rolled into balls, mixed with boiling water to form a glue-like paste (papeda), or as a pancake. Sago is often produced commercially in the form of "pearls" (small rounded starch aggregates, partly gelatinized by heating). Sago pearls can be boiled with water or milk and sugar to make a sweet sago pudding. Sago pearls are similar in appearance to the pearled starches of other origin, e.g. cassava starch (tapioca) and potato starch, and they may be used interchangeably in some dishes.

The name sago is also sometimes used for starch extracted from other sources, especially the sago cycad, Cycas revoluta. The sago cycad is also commonly known (confusingly) as the sago palm, although this is a misnomer as cycads are not palms. Extracting edible starch from the sago cycad requires special care due to the poisonous nature of cycads. Cycad sago is used for many of the same purposes as palm sago.

The fruit of palm trees from which the sago is produced is not allowed to ripen fully. The full ripening completes the life cycle of the tree and exhausts the starch reserves in the trunk to produce the seeds. It leaves a hollow shell and causes the tree to die. The palms are cut down when they are about 15 years old, just before or shortly after the inflorescence appears. The stems, which grow 10 to 15 metres high), are split out. The starch-containing pith is taken from the stems and ground to powder. The powder is kneaded in water over a cloth or sieve to release the starch. The water with the starch passes into a trough where the starch settles. After a few washings, the starch is ready to be used in cooking. A single palm yields about 800 pounds (360 kilograms) of dry starch.

Sago (disambiguation)

Sago is a starch extracted from the stems of metroxylon sagu palms.

Sago may also refer to:

In plants:

Metroxylon sagu or sago palm, a palm from which sago is extracted

Cycas revoluta or sago cycad, a cycad from which starch also known as sago is extracted

Zamia integrifolia, another cycad plant sometimes called wild sagoIn food:

Sago pudding, a sweet pudding made from sago

Sap Sago, US brand of Swiss Schabziger cheese

Sago soup, a Cantonese variant of tapioca puddingIn places:

Mount Sago, Indonesia

Sago, Burkina Faso

Sago, Côte d'Ivoire

Sago, West Virginia, United States

Sago Lane, Singapore

Sago Street, Singapore

Sago Township, Minnesota, United StatesIn other uses:

Sago Mine disaster, West Virginia, 2006

Sago palm weevil or red palm weevil, Rhynchophorus ferrugineus

Sago worm, the larva of the sago palm weevil

Sago palm

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:

Metroxylon sagu (true sago palm), a species in the palm family (Arecaceae) native to Southeast Asia


Cycas revoluta, (king sago palm), native to Japan and widely cultivated as an ornamental plant

Cycas rumphii, (queen sago palm), native to southeast Asia

Cycas circinalis, (queen sago palm), native to India


A strobilus (plural: strobili) 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 many botanists restrict the use of the term cone to the woody seed strobili of conifers. Strobili are characterized by a central axis (anatomically a stem) surrounded by spirally arranged or decussate structures that may be modified leaves or modified stems.

Leaves that bear sporangia are called sporophylls, while sporangia-bearing stems are called sporangiophores.

Taiheiyo evergreen forests

The Taiheiyo evergreen forests is a temperate broadleaf forest ecoregion of Japan.

The ecoregion covers an area of 138,300 square kilometers (53,400 sq mi) on the Pacific (Taiheiyo) side of the islands of Honshū, Shikoku, and Kyūshū. The influence of the Japan Current creates a humid climate with mild winters and a long growing season, which nurtured evergreen broadleaf forests. Laurel forests grew near the coast, and Oak forests were predominant inland. At higher elevations, the Taiheiyo evergreen forests yielded to the Taiheiyo montane deciduous forests of the interior.The forests include a mix of species with origins in temperate and tropical Asia. Species with tropical origins include two species of the conifer Podocarpus,, two species of Pittosporum, several species in the Laurel family (Machilus, Neolitsea, and Cinnamomum), and the Cycad Cycas revoluta. Trees with origins in temperate Eurasia include species of evergreen Oaks and Castanopsis.The ecoregion is home to Japan's largest cities, including Tokyo, Yokohama, Osaka, and Nagoya, and most of forests have been converted to agriculture or cities. Remnant areas of forest remain around temples and shrines, on steep slopes, and in gorges. Secondary growth woodlands, called Satoyama, are found on hillsides bordering farmlands.

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