Cycas Revoluta

''Cycas revoluta'' (Sotetsu apanese 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. 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. The leaves grow from the trunk and start out as small leaves near the centre of the plant.

Names

Cycads' only relations to the true palms (Arecaceae) is that both are vascular plants and seed plants. The Latin specific epithet ''revoluta'' means "curled back", in reference to the leaves. This is also called kungi (comb) palm in Urdu speaking areas.

Description

This very symmetrical plant supports a crown of shiny, dark green leaves on a thick shaggy trunk that is typically about 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 long when the plants are of a reproductive age. They grow out into a feather-like rosette to in diameter. The crowded, stiff, narrow leaflets are long and have strongly recurved or revolute edges. The basal leaflets become more like spines. The petiole or stems of the sago cycad are 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

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.

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). ''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 (confirmed 2017).

Sago

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.

Chemistry

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

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.''Toxicology Brief: Cycad toxicosis in dogs'', Hany Youssef, Veterinary Medicine , May 1, 2008

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Gallery

Image:Cycas revoluta female cone01.jpg, Female reproductive structure
Image:Cycas revoluta01.jpg
Image:Cycas revoluta02.jpg
Image:Cycas revoluta004.jpg
Image:Cycas revoluta new leafs.JPG, New leaves
Image:Sago Palm.jpg
Image:Cyca-revoluta.jpg
Image:Cycas revoluta1328A.JPG
Image:Cycas Sago.palm.arp.750pix.jpg, Young plant
Image:Cycas revoluta seeds.jpg, Seeds
Image:Cycas_revoluta_seedling.jpg, Seedling
Image:CYUS PALM.JPG
Image:Funchal Botanical garden - Cycas revoluta.JPG
Image:Funchal, Monte - Cycas revoluta IMG 1970.JPG
Image:Funchal, Monte - Cycas revoluta IMG 1907.JPG
Image:KG Cycas revoluta.jpg
Image:Branching Cycas revoluta.jpg, A sixteen-year-old two-branched specimen
Cycas revoluta MHNT.BOT.2018.28.17.jpg, MHNT

See also

Kanzen Teruya

References

External links

The Cycad Pages: ''Cycas revoluta''


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.
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

{{Taxonbar, from=Q161517

revoluta
Flora of Japan
Flora of the Ryukyu Islands
Garden plants
Near threatened plants
Plants used in bonsai
Plants described in 1782