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|Japanese sago palm|
|Leaves and male cone of Cycas revoluta|
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Least Concern ( IUCN 3.1 ) 
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.
- 1 Names
- 2 Description
- 3 Cultivation and uses
- 3.1 Sago
- 4 Chemistry
- 5 Toxicity
- 6 Gallery
- 7 References
- 8 External links
Names[ edit ]
Cycads ‘ only relation to the true palms ( Arecaceae ) is that both are seed plants . The Latin specific epithet revoluta means “curled back”,  in reference to the leaves. This is also called Kungi (comb) Palm in Punjabi speaking areas. 
Description[ edit ]
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. 
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.  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[ edit ]
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.
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), and several healthy plants 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 this temperate climate, but will usually flush (or grow) several new leaves by spring.
This plant has gained the Royal Horticultural Society ‘s Award of Garden Merit  (confirmed 2017). 
Sago[ edit ]
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 fibrolemellar hepatocellular carcinoma.
Aulacaspis yasumatsui is a scale insect feeding on C. revoluta, and unchecked is able to destroy the plant. 
Chemistry[ edit ]
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.  Leaflets also contain biflavonoids .  Estragole is the primary volatile compound emitted from the male and female cones of C. revoluta. 
Toxicity[ edit ]
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.  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).  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.  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. 
Gallery[ edit ]
Female reproductive structure
A sixteen year-old two-branched specimen
References[ edit ]
|Wikimedia Commons has media related to Cycas revoluta .|
|Wikispecies has information related to Cycas revoluta|
- ^ Hill (2003). “Cycas revoluta” . IUCN Red List of Threatened Species. Version 2006. International Union for Conservation of Nature . Retrieved 11 May 2006.
- ^ D. Gledhill The Names of Plants , p. 329, at Google Books
- ^ Harrison, Lorraine (2012). RHS Latin for gardeners. United Kingdom: Mitchell Beazley. p. 224. ISBN 9781845337315 .
- ^ Thunberg, Carl Peter. 1782. Verhandelingen uitgegeeven door de hollandse maatschappy der weetenschappen, te Haarlem 20(2): 424, 426–427.
- ^ 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
- ^ “Cycas revoluta” . Royal Horticultural Society. Retrieved 22 July 2013.
- ^ “AGM Plants – Ornamental” (PDF). Royal Horticultural Society. July 2017. p. 22. Retrieved 24 January 2018.
- ^ 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 )
- ^ 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 )
- ^ 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
- ^ 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
- ^ Suspected cycad (Cycas revoluta) intoxication in dogs, Botha CJ, Naude TW, Swan GE, et al.| J S Afr Vet Assoc | 1991
- ^ Muller-Esneault, Susan (2009). “Cycas Revoluta: The Sago Palm, or Cycad Toxicity” . Critterology.com.
- ^ Selected poisonous plant concerns small animals, Knight MW, Dorman DC | Vet Med | 1997 | 92(3):260-272
- ^ Toxicology Brief: Cycad toxicosis in dogs, Hany Youssef| Veterinary Medicine | May 1, 2008 | 
- The Cycad Pages: Cycas revoluta
- Sago Palm : University of Arizona Pima County Cooperative Extension
- The Sago Palm, Cycas revoluta by Phil Bergman
- Cycads: their evolution, toxins, herbivores and insect pollinators. Schneider D, Wink M, Sporer F, Lounibos P. Naturwissenschaften. 2002 Jul;89(7):281-94. Review. PMID 12216856
External links[ edit ]
- Microsporophyll Macrosporophyll Seeds Videos – Flavon’s Wild herb and Alpine plants
- line drawing of Cycas revoluta, Manual of Vascular Plants of the Lower Yangtze Valley China Illustration fig. 31
- line drawing of Cycas revoluta, Flora of China Illustrations vol. 4, fig. 2, 1-6
- IUCN Red List least concern species
- Flora of Japan
- Flora of the Ryukyu Islands
- Garden plants
- Near threatened plants
- Plants used in bonsai
- Poisonous plants
- Plants described in 1782
- Articles with ‘species’ microformats
- Commons category link from Wikidata
- Wikipedia articles with NDL identifiers
- Taxonbars with 20–24 taxon IDs
- This page was last edited on 8 May 2018, at 10:46 (UTC).
- Text is available under the Creative Commons Attribution-ShareAlike License ;
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Few plants meet with such universal adoration and approval as Cycas revoluta. Everyone loves them for their drama and perfection. There’s fossil evidence that they’ve evolved very little for many millions of years so we’d describe them as ‘primitive’. Primitive plants have two things in common : 1. Their growth patterns are unpredictable (cf. Monkey Puzzle trees, Ginko trees and Coelacanths) and 2. They’re unsusceptible to pests and diseases. These can quite happily sit around for several years producing no new growth at all and then suddenly, one summer, transform themselves in 2 or 3 weeks with 30 lovely new fronds. When new fronds are emerging (this goes for tree ferns and one or two other plants) – if they’re in a pot – don’t move them. The plant’s internal command centre is organizing its fronds in a way to gain the maximum light. To us, the result is beautiful symmetry. Move the plants while the fronds (leaves?) are unfurling and as far as it’s concerned, the sun’s changed position and the fronds will twist. The result’s a hopeless mess. Once all the fronds are out and settled down, then you can move the plant if you need to.
During its long periods of doing nothing but looking lovely, the metabolism is so slow that it’s almost dead. When you see the new fronds emerge (it’s obvious), the metabolism goes from nought to a hundred in a day. Assuming it’s in a pot (central London is probably the only place you’d have it in the ground), then is the time to feed and water it – or even repot it. This means moving it so you’d need to do that as soon as you see the new fronds erupt. Don’t leave it too long or you’ll have twisted frond trouble. Beware of over watering when it’s not growing. It doesn’t need much water and the roots could rot if it has no use for the water. If it’s been over watered it could end up looking pretty sorry for itself with yellowing fronds. In summer, you could try cutting off the fronds and feeding with Epsom Salts (Magnesium sulphate). Killing these plants is a major accomplishment. They always seem to come back to life no matter how criminally negligent of the poor things you’ve been.
They’re native to southern Japan and are thought to be the hardiest of the cycads, many of which come from South Africa. They’ll tolerate at least -5°c without trouble but they need warm summers to produce new growth which is why central London (significantly warmer summers and milder winters) is the best place to plant them out permanently. We have a customer who’s had one growing outside in Horsham for many years. It made a good story. Is it Cycas revoluta? Yes. Is it alive? Yes. Does it look lovely? No it doesn’t.
We bring the big ones in from Italy and the little ones we grow from the occasional suckers from the big ones. They’re tied up with soft ribbon for transportation and it took us a long time to realize that brown marks on the fronds were manifestations of damage from the ribbon. The reason it took so long gives one an understanding of my comment about them being almost dead when they’re not producing new fronds. Everything happens very very very slowly. We’d untie the plants but the damage would come to life as much as two months later. One doesn’t immediately make a connection. One wouldn’t. As a result, virtually all the ones we sell have fronds that have grown in the nursery and we don’t wrap them for transport and now you know why.
Assuming you’d overwinter these in pots in a conservatory or similar, look out for Mealy Bug on the trunk and Scale Insect under the leaves. Spot them early and kill each one with a pen knife or use a bug gun if they’re a bit out of hand. They are not attractive to bugs generally so it’s unlikely to be a problem but still worth looking out for. Generally, they thrive on neglect. Fuss over them and you’ll probably kill it eventually. Cut off the old unsightly leaves. Very occasionally they flower. Mighty eruptions according to whether they’re male or female that interrupt the smooth running of things (as usual) but things will settle down eventually (as usual). You don’t need to phone us when this happens. There’s nothing either you are we can do about it.
IF IT HAS A RED TRAFFIC LIGHT
Hardy in Atlantic Seaboard gardens, The Channel Islands, gardens in Central London (and other large cities) and conservatories.
This is only meant as a guide; there are some plants with red labels that would only survive in extremely favoured spots such as The Isles of Scilly or coastal south-west Ireland.
We’re always on hand to give advice about plants and their frost hardiness.
Please remember that these coloured labels are only a rough guide.
General Point about Plant Hardiness: The commonly held belief that it’s better to ‘plant small’ is perfectly true with herbaceous plants, but not necessarily true with woody plants. They need some ‘wood’ on them to survive severe cold – so plants of marginal hardiness in very cold areas should really be planted LARGER, rather than smaller, wherever possible.
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