Common Name:

General Information

Encephalartos sclavoi is a slow-growing, evergreen, palm-like plant with an erect to decumbent main stem that can eventually be around 1 - 4 metres tall and 30 - 35cm in diameter; this is topped by a crown of numerous, erect, large leaves each around 180 - 200cm long. The plant suckers from the base to form clumps with 2 - 6 stems[].
The seeds are harvested for medicinal purposes by traditional healers[]. A very attractive plant, it is grown as an ornamental[].
Encephalartos sclavoi has a very small area of occupancy, is known from a single location where the population size is less than 50 mature individuals, and there is continuing decline due to loss in the extent and quality of habitat and decline in the population due to collection by traditional healers and by cycad collectors. The plant is classified as 'Critically 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

East tropical Africa - northeastern Tanzania

Habitat

Steep, relatively dry, south facing rocky slopes in grassland and on rocky outcrops surrounded by montane forest, growing between rocks on sheer precipitous granite and gneiss promontories; at elevations from 1,800 - 2,100 metres[].

Properties

Conservation Status	Critically Endangered
Medicinal Rating
Habit	Evergreen Tree
Height	2.50 m
Growth Rate	Slow
Pollinators	Insects
Self-fertile	No
Cultivation Status	Ornamental, Wild

Cultivation Details

Although the habitat of Encephalartos sclavoi is close to the equator, the high elevation at which it occurs gives it a remarkable degree of cold tolerance.
An easily grown plant, succeeding in full sun without its leaves burning[]. 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[].
Cycad species 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[].
Encephalartos species always produce full-sized seeds, even if the cone has not been pollinated, in which case the resulting seed is not viable but appears normal in every other respect[]

Edible Uses

Caution should be exercised in the use of this plant for food - see notes above on toxicity[].

The short to long ovoid seed is around 32 - 44mm long and 19 - 23mm in diameter[].
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[].

Medicinal

The seeds are used medicinally[].

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. 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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