For many years, Cycas micronesica was misidentified as either Cycas circinalis or Cycas rumphii. It can be distinguished from those two species by its larger seeds, probably the largest in the genus, and its predominantly unarmed petiole[].

Common Name: Fadan

General Information

Cycas micronesica is a slow-growing, evergreen palm-like plant with an erect main stem that can eventually be up to 8 metres tall (exceptionally to 12 metres) and 14 - 25cm in diameter; this is topped by a crown of numerous large leaves each around 1.8 - 2.2 metres long[].
The plant is harvested from the wild for local use as a food. On the island of Guam, the plant is referred to as 'federico' and is said to be widely cultivated as a food[]
Populations of Cycas micronesica are relatively stable on a few of the islands but are declining on most islands due to development of the land for agriculture, tourism etc. Plants are also highly vulnerable to an invasion of scale insects and, on Guam, populations are declining rapidly. The measured decline of 3% in five years is expected to increase as heavily infested plants die. Seedlings and juveniles have also died back completely on Guam meaning there is no replacement of adults. It is therefore anticipated that the decline over the current and future generations (capped at
100 years from now) will exceed 50%. The plant is classified as 'Endangered' in the IUCN Red List of Threatened Species(2010)[].

Known Hazards

We have no specific information for this species, but most if not all members of this genus are believed to contain toxins. The two main toxic compounds that have been identified are cycasin and macrozamin. When ingested in sufficient quantities, these compounds are extremely poisonous to humans and many other animals, and have been shown to cause liver damage and cancer. Cycasin and macrozamin have a cumulative effect upon the body and are suspected of causing neurological disorders when ingested in small amounts over long periods of time.
There is a long history of human use of this genus as a starch-rich food, but it should be noted that the plants needed to be treated in various ways in order to remove any toxic principles. Caution should be exercised even with properly prepared foods, since even then regular consumption may lead to severe health problems and death. Since many of these species are becoming increasingly rare in the wild, this is probably a food best left to times of food shortage when other, better foods, are not available[, ].

Botanical References

Range

Northwest Pacific - Caroline Is., Marianas, Marshall Is.

Habitat

Closed forest on coral limestone or coral sand, or occasionally on volcanic soils on islands where these occur[].

Properties

Conservation Status	Endangered
Edibility Rating
Habit	Tree
Height	6.00 m
Growth Rate	Medium
Pollinators	Insects
Self-fertile	No
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

Cycas micronesica is a plant of tropical regions and is sensitive to frosts.
An almost universal requirement for cycads is a well-drained but moisture-retentive soil, and by far the best soils are sandy gravels and light loams which provide the required drainage and aeration necessary for good growth. Cycads will generally not grow well in clay soils unless those soils are heavily amended with sand and organic matter[]. A neutral soil (pH 7), is generally best for most species of cycads and allows the proper absorption of nutrients. A slightly acid soil is better for most cycads than a basic one[].
In cultivation, this species is one of the fastest growing in the genus, and under the right conditions it will form large specimens in a very few years.[]
Species in this genus can usually be transplanted easily even when quite large. The best time for moving them is just before the beginning of a new growing season, the roots being trimmed if they are damaged and perhaps some leaves being removed. New roots should develop quickly as the season progresses[].
Species in this genus form structures known as coralloid roots. These roots branch off from the taproot or secondary roots and are distinctive in that they grow laterally or upward, forming a nodular mass at the apex. These coralloid roots occur slightly below or slightly above the soil surface and generally contain cyanobacteria, also known as blue-green algae. These are able to fix atmospheric nitrogen and make it available as a nutrient to the plant. The ability to extract this important nutrient from the air explains how many cycad species are able to survive on almost sterile soils[].
A dioecious species, with individual plants producing either all male or all female cones. Therefore both male and female forms of the plant need to be grown if seed is required[]. On very rare occasions, usually when a plant has been under severe stress, it can change sex and produce either all female or all male cones[].

Edible Uses

Species in this genus are generally toxic unless the food is prepared correctly. See notes above on toxicity.

On Guam and Rota in the Mariana Islands, the Chamorro Indians have traditionally used Cycas micronesica as a source of food and medicine. Although the local population was warned of the possible hazards involved with eating starch derived from cycads, its use persists[].
A flour is produced from the central pith of the stem or the endosperm of the seed. This substance is rich in starch but also contains a poisonous constituent that can cause paralysis in humans and other animals. The Chamorro first learned how to process and detoxify the seed and stem of this cycad from the Spanish around 1800 CE. Processing the material consists of chopping up the seeds or pith, soaking in water for 10 days, then drying and grinding into a powder. From this flour, tortillas can be made.

The ovoid to subglobose, flattened, seeds are 50 - 60mm long, 45 - 50mm in diameter[].

Medicinal

None known

Other Uses

None known

Propagation

Seeds - best sown as soon as they are ripe, though the seeds of many species will take a few months to finish maturing the embryo before they are ready to germinate. The seeds can sometimes take 2 years to germinate. Sow the seeds in a tray in a freely-draining medium and place in moderate shade. Bottom heat at about 27°c will hasten seed germination dramatically. Young roots are quite brittle and once germination takes place, the root grows rapidly. It is important to pot up the seedlings at this time in order to give them enough root-space. Grow on the plants in pots until large enough to plant out[].
Division of off-sets or suckers is best carried out just before the plant comes in to new growth at the start of the growing season[].

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