Common Name:

General Information

Cycas thouarsii is a slow-growing, evergreen, palm-like plant with an erect main stem that can eventually be around 4 - 10 metres tall and 20 - 45cm in diameter; this is topped by a crown of around 40 large leaves each around 1.5 - 3 metres long. The main stem is usually unbranched in younger plants, but often becoming branched in older plants[].
The plant is harvested from the wild for local use as a food and source of materials. It is often grown as an ornamental[].
Cycas thouarsii is a widespread and abundant species which occurs at several locations along the east coast of Africa and in Madagascar. Although there are some threats, these are not significant enough to warrant listing the species in a threatened category. The plant is classified as 'Least Concern' 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

Eastern tropical Africa - Kenya, Tanzania, Mozambique, Madagascar and the Comores

Habitat

Open woodland or forest margins, usually near the coast, occurring sparsely as individuals or in small groups; at elevations up to 200 metres[].

Properties

Conservation Status	Least Concern
Edibility Rating
Other Uses Rating
Habit	Evergreen Tree
Height	8.00 m
Growth Rate	Slow
Pollinators	Insects
Self-fertile	No
Cultivation Status	Ornamental, Wild

Cultivation Details

Cycas thouarsii is found in the tropical climate of eastern Africa where summer temperatures are relatively high, and
winters are frost-free. Annual rainfall ranges between 1,000 - 3,000mm[]. For this cycad to grow well it must have plenty of heat and some humidity. It has been grown in some areas with a Mediterranean climate, but it does not do as well as in the Tropics[].
The plant usually grows in the wild on sand or on coral formations[]. 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[].
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.
A starchlike meal is made from the seeds and stems[].
Cycads have often been used traditionally as a source of food starch, obtained either from the seeds or from the stems, and it is probable that the seed kernels and stem pith of all cycads can be used as food after treatment to remove any toxic principle that may be present (See notes above on toxicity). The starch would appear to be of particular importance as a source of sustenance during hard times or in areas where the food supply is naturally limited[].
The broad ovoid, slightly flattened seed is 47 - 54mm long and 37 - 44mm in diameter[].

The young, tender, emergent leaves are used as a vegetable[].

Medicinal

A gum obtained from the plant has been used medicinally, particularly as an agent that is said to produce rapid suppuration when applied to malignant ulcers. The gum also has the repute of being a good antidote for snake and insect bites[].

Other Uses

A gum exudes through wounds in the plant, especially from the megasporophylls, stems and leaves[]. It is used medicinally and as an adhesive[].
When placed in water, Cycas gum begins to swell almost immediately. By the end of several days, it expands to many times its original size and becomes so colourless and transparent that it cannot be seen in water but must be felt for with a rod[]. Cycas gum has been likened in its properties to that of Sterculia setigera[]

Mature leaves are woven into mats[].

Propagation

Seed -

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