Cycas revoluta

Cycas revoluta (sotetsu (Japanese ソテツ) sago palm, king sago, cica, church palm, true sago palm from India, false palm or cica as its common name in Spanish) is a plant native to southern Japan, a paradigmatic example of pseudopalms or cycads. It is usually grown as an indoor plant, since it can't stand the cold, although in Spain it thrives along the entire coastal strip and especially in the Mediterranean area.

Description

This highly symmetrical plant bears a crown of glossy, dark green leaves on a thick, hairy trunk that is typically about 20 cm (7.9 in) in diameter, sometimes wider. The trunk is very low to underground in young plants, but elongates above ground with age. In very old specimens it can measure about 6-7 m (more than 20 feet) in trunk height; however, the plant is very slow growing and requires around 50-100 years to reach this height. The trunks can branch several times, thus producing multiple leaf heads.

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

The roots form what is called "coralloid," a symbiosis with the cyanobacterium Anabaena (blue-green algae), which fixes nitrogen and, in association with tissues from the root, they produce beneficial amino acids such as asparagine and citrulline. Tannin-rich cells are located on either side of the algae layer to resist invasion by algae.

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

Toxicity

A copy of Cycas revoluta bonsai.

Detail

Inflorescence

Cycas revoluta - MHNT

If ingested it is extremely poisonous, both to humans and animals. Domestic animals are at higher risk as they find the plant particularly tasty. Clinical symptoms develop within 12 hours of ingestion and may include vomiting, diarrhea, weakness, fainting spells, liver failure or liver toxicity characterized by jaundice, cirrhosis and ascites. Domestic animals may appear dejected, have nosebleeds (epistaxis), have melena (blood in the droppings), hematochezia, and hemarthrosis (blood in the joints). The Animal Poison Control Center (ASPCA) estimates a mortality rate of between 50 and 75 percent when the plant is ingested. The incidence of its ingestion by domestic animals has risen by 200% in the last five years. If any amount of the plant is ingested, a poison control center should be contacted immediately. Effects of ingestion may 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 doses leads to liver failure. Other toxins include Beta-methylamino-L-alanine, a neurotoxic amino acid, and an unidentified toxin that has been shown to cause paralysis in cattle.

Taxonomy

Cycas revoluta was described by Carl Peter Thunberg and published in Verhandelingen uitgegeeven door de hollandse maatschappy der weetenschappen, te Haarlem 20 (2): 424, 426–427. 1782.

Sinonimia

• Cycas inermis Oudem.
• Cycas miquelii Warb.
• Cycas revoluta var. revoluta
• Epicycas miquelii (Warb.) from Laub.