CYCAS REVOLUTA: CHARACTERISTICS, HABITAT, TOXICITY, CARE - BIOLOGY - 2025

Cycas revoluta is a gymnosperm species belonging to the Cycadaceae family. Contrary to what many people think, this plant does not belong to the group of palm trees. It is commonly known as cica, cycas, sago palm, Japan sago. In turn, in Japan it is often referred to as king sago palm or sotetsu.

It is a slow-growing, perennial, palm-like plant with a longevity of more than 200 years. It has a medium-thick cylindrical stem, leaves arranged in a rosette, pinnately compound and odd-pinnate, about 50 to 150 cm long, leathery and sharp.

Cycas revoluta. Source: pixabay.com

Being a dioecious plant, it presents its sexual structures in separate plants. The male structures produce cones or strobili in their center and look like a pineapple, while the female structure forms a set of ovaries that after fertilization produces large yellow-orange seeds.

This plant produces a substance called cicasin that is toxic to both animals and humans. The ingestion of cyca produces vomiting, weakness, diarrhea, failure or liver toxicity that triggers jaundice, ascites and cirrhosis.

Its main use is as an ornamental, it has great commercial value, and the seeds are generally exported from Japan. Despite its toxicity, in some parts of the world they consume parts of this plant, and use its extracts to prepare alcoholic beverages and gums.

characteristics

Appearance

-Species: Cycas revoluta Thunb.

Some synonyms for this plant are: Cycas miquelii, Cycas revoluta var. brevifrons, Cycas revoluta var. planifolia, Cycas revoluta var. prolifera, Cycas revoluta var. revoluta, Cycas revoluta var. robust, Epicycas miquelii.

Detail of new leaves of Cycas revoluta. Source: Aesculapius

Habitat and distribution

This plant grows well in loamy soils, with slight acidity, but very rich in organic content and mineral elements. Grows in semi-shady conditions. It resists the cold seasons, but without strong frosts, and it develops well in temperate climates.

It is a species distributed mainly in China and Japan. It is also found in countries such as Bolivia, Colombia, Costa Rica, El Salvador, Guatemala, Honduras, Panama, Venezuela, among others.

An interesting fact is that the roots of these plants form a symbiosis between them and the cyanobacteria Anabaena cycadae and Nostoc sp. This symbiosis allows the fixation of molecular nitrogen through the nitrogenase enzyme present in these prokaryotes.

Cycas revoluta has a medium-thick trunk. Source: wikimedia commons.

Toxicity

This plant produces a substance called cicasin that is toxic (lethal) for both animals and humans. Ingestion of cyca, particularly by domestic animals, produces vomiting, weakness, diarrhea, liver failure or toxicity that triggers jaundice, ascites, and cirrhosis.

The seeds of cycas contain the highest presence of cycasin. These seeds are the basis of a drink called doku sake (poisonous shake), which produces certain violent effects in people who drink it, and can even cause death.

On the other hand, the use of leaves, especially of young shoots can cause toxic effects such as rheumatism. Other toxic substances are beta-methylamino L-alanine, an amino acid that behaves as a neurotoxic, in addition to another unidentified toxin that causes paralysis in cows.

The seeds of Cycas revoluta are of considerable size. Source: Aesculapius

Applications

Mainly, this species is used as an ornamental for both gardens and public areas, and also as bonsai. It is considered the most commercialized cyca species worldwide. Especially in Japan they are used for ceremonies or funerals.

In addition to its commercial exploitation, in Panama for example, the internal part of the stem is used as food. In India it is used industrially to extract "sago", a substance that contains a lot of starch and is used to thicken sauces.

The seeds or nuts of Cycas revoluta are also used as food in Sri Lanka, India and Indonesia. These seeds contain about 13% crude protein and about 70% starch.

In other parts of the world, the stem of this plant is part of the restaurant menu. Sago extract is used to prepare alcoholic beverages and to make gums. These products are prepared from the exudates of the female reproductive structures.

Cycas plants are highly ornamental and of high commercial value. Source: 663highland

Care

- Spread

Cycas are propagated through seeds. To do this, they must be immersed in water and discarded those that float, since this indicates that the embryo is not developed. The viable seeds are then treated with nematicides to protect them during germination.

For germination, a wet bed composed of sawdust must be prepared and the seeds distributed on them. Then it must be watered and foliar fertilized for optimal development during the seedling phase (6 months to 1 year).

In the same way, this species can also reproduce by means of suckers, which are carefully removed as they emerge from the sides of the mother plant. This form is used less frequently, since it is difficult to standardize the size of the suckers to be sown in the field and that the plants do not show differences in growth.

Another way is from bulbs, which allow it to be propagated at any age and kept in a pot. For its part, the in vitro form of propagation has not yet yielded good results.

- Irrigation

It is recommended to water abundantly in the seedling stage, since cycas have a high water requirement at this stage. This is because the seed requires high humidity to induce the germination process.

Likewise, when sowing from the bulb, it must be done in a fairly humid environment so that the sprout begins to develop.

In the field transplant stage, irrigation can be reduced only to that provided by rainwater.

- Fertilization

Fertilizing is often done for cycas as for palms. For this, it is recommended to use controlled release or slow release fertilizers, which are normally used in long-cycle crops.

Subscribing can be done with NPK formula 18-6-8, during the early stages of growth.

At the time of the growth of the crowns of the leaves, a fertilization with the formula 24-7-8 NPK can be applied quarterly, as well as some microelements.

The fertilization must take into account that a high application of nitrogen is not necessary since the symbiosis that it carries out with cyanobacteria, allows the plant to obtain this macroelement from said association; but the application of magnesium in a foliar or edaphic form is recommended.

- Plagues and diseases

Aulacaspis yasumatsui

It is a scale, a hemiptere that attacks cycas in all parts of the world. It is known as the Cycad Aulacaspis Scale (CAS). It produces specific chlorotic spots on the leaves.

This scale is surrounded by a waxy coating that covers the plant and its roots. The leaves dry out, turn brown, and later the plant dies.

Systemic insecticides containing imidaclopyr and thiamethoxam are used to control this scale. Another form of control is using the agricultural oil in a foliar form to prevent the scale from adhering to the leaves.

It can also be controlled biologically by the insects Cocobius fulvus, and Cybocephalus binotatus.

CSNV virus

It corresponds to a virus that only affects gymnosperms. It belongs to the Nepovirus, subgroup b, family Comoviridae.

It produces necrosis and malformation in new leaves. This virus is transmitted by seeds, through nematodes and asexual spread.

Chasparria or leaf necrosis

There is a series of pathogenic microorganisms associated with the lesions of the disease known as chasparria in cycas. These pathogens are Colletotrichum proteae, Fusarium sp., Pestalotiopsis foedans, Nigrospora sphaerica, as well as some species of Sclerotium.

This disease produces necrosis in the leaves, and loss of color in the leaflets. It is a very contagious disease at any stage of development. Chemical, physical and cultural control is recommended to treat this disease.

References

1. Sánchez Valverde, M. 2015. Cycas revoluta Thunb, Generalities, crop management and diseases. 49 p. Taken from: researchgate.net
2. Catalog of Life: 2019 Annual Checklist. Species details: Cycas revoluta Thunb. Taken from: catalogueoflife.org
3. Tropics. 2019. Cycas revoluta Thunb. Taken from: tropicos.org
4. Botanical Garden of the University of Malaga. 2019. Cycas revoluta - JB-75-08. Taken from: jardinbotanico.uma.es
5. Flowers and plants. 2009. The Cycas revoluta in the garden. Taken from: floresyplantas.net