Cycas revoluta

This article is about the cycad sago palm. For the true sago palm, see Metroxylon sagu.

Cycas revoluta
Leaves and male cone of Cycas revoluta
Conservation status
Near Threatened (IUCN 3.1)[1]
Scientific classification
Kingdom:	Plantae
Division:	Cycadophyta
Class:	Cycadopsida
Order:	Cycadales
Family:	Cycadaceae
Genus:	Cycas
Species:	C. revoluta
Binomial name
Cycas revoluta Thunb.

Cycas revoluta (the sago cycad), is a plant native to southern Japan. Though often known by the common name of king sago palm, or just sago palm, it is not a palm at all, but a cycad.

Description

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 multiple times, thus producing multiple heads of leaves.

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 that must be avoided.

Propagation of Cycas revoluta is either by seed or by removal of basal offsets. As with other cycads, it is dioecious, with the males bearing cones and the females bearing groups of megasporophylls. Pollination can be done naturally by insects or artificially.

Cultivation and Uses

Cycas revoluta 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.

Of all the cycads, the Sago Palm is the most popular in horticulture. 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 native to various areas of southern Japan and is thus tolerant of mild to somewhat cold temperatures, provided the ground is dry. Frost damage can occur at temperatures below −10 °C (14 °F) and there are several healthy plants that have been grown with little protection as far north as Nashville, Tennessee and Newport News, Virginia, both are in zone 7b. C. revoluta usually defoliates in this temperate climate, but it usually will flush (or grow) several new leaves by April. It does however require hot summers with mean temperatures of 30 to 35 °C (86 to 95 °F) for successful growth, making outdoor growing impossible in colder places such as northern Europe or the Northeast US, even where winter temperatures are not too cold. One disadvantage of its domestic use is that it is poisonous to animals (this includes humans).

Toxicity

Cycad Sago Palm is extremely poisonous to animals (this includes humans) if ingested. Pets are at particular risk since they seem to find the plant very palatable.^[2] Clinical symptoms of ingestion will develop within 12 hours and may include vomiting, diarrhea, weakness, seizures, 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).^[3] The ASPCA Animal Poison Control Center estimates a fatality rate of 50 to 75 percent when ingestion of the Sago Palm is involved. The incidence of Sago Palm ingestion by pets has risen by over 200% in the last five years.^[4] 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.^[5] 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.^[6]

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  female reproductive structure

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  new leaves

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  young

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  seeds

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  seedling

• Cycas Palm.JPG

  Cycas revoluta

• Funchal Botanical garden - Cycas revoluta.JPG, 22 March
• Funchal, Monte - Cycas revoluta IMG 1970.JPG, 23 March
• Funchal, Monte - Cycas revoluta IMG 1907.JPG, 23 March
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Notes

1. ^ Hill (2003). Cycas revoluta. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 11 May 2006.
2. ^ Suspected cycad (Cycas revoluta) intoxication in dogs, Botha CJ, Naude TW, Swan GE, et al.| J S Afr Vet Assoc | 1991
3. ^ Muller-Esneault, Susan (2009). "Cycas Revoluta: The Sago Palm, or Cycad Toxicity". Critterology.com. http://www.critterology.com/articles/cycas-revoluta-sago-palm-or-cycad-toxicity. 
4. ^ "Trouble in Paradise: Sago Palm" (Press release). ASPCA. 2008-07-16. http://www.aspca.org/site/PageServer?pagename=press_071608. 
5. ^ Selected poisonous plant concerns small animals, Knight MW, Dorman DC | Vet Med | 1997 | 92(3):260-272
6. ^ Toxicology Brief: Cycad toxicosis in dogs, Hany Youssef| Veterinary Medicine | May 1, 2008 | [1]

References

• 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

• MicrosporophyllMacrosporophyllSeedsVideos - Flavon's Wild herb and Alpine plants