Common Name:

General Information

Mansonia altissima is an evergreen tree with a small, dense, ovoid, crown and branches that are almost horizontal at first, but later drooping; it can grow up to 45 metres tall. The cylindrical, generally straight bole can be branchless for up to 30 metres and up to 100cm, occasionally even 150cm, in diameter; it sometimes has narrow buttresses[].
A valuable wood, it is commonly harvested from the wild and exported, especially to the USA and Europe, where it is seen as a substitute for walnut[]. The plant has been tried in plantations and in enrichment plantings, but
no results are known. It is occasionally retained or grown in agroforestry systems[].

Known Hazards

The bark is very poisonous and in parts of south-western Côte d’Ivoire it is the main component of a very effective arrow-poison, also used in spear traps for large game. In other parts of its range the bark is a component of arrow poisons too[].
In processing, the wood produces high levels of dust which can cause serious health problems to workers. The dust may cause dermatitis, nose-bleeding, throat irritation, asthma and eczema, the reactions becoming stronger on repeated exposure. Heart troubles have also been reported. Pigs given the sawdust as litter developed severe contact dermatitis and piglets even died. The toxins in the wood, even in the form of thin veneer, are resistant to oxidation and are heat-stable; they remain effective for many years[].
Ethanol and chloroform extracts of the bark have shown a very strong toxicity against several mammals[].

Botanical References

Range

West tropical Africa - Guinea and Cote D'Ivoire to the Central African Republic and northern DR Congo.

Habitat

Dense semi-deciduous forest, extending to patches of dense forest in the savannah[]. Adult trees are more common in logged or burnt forest than in undisturbed forest[].

Properties

Medicinal Rating
Other Uses Rating
Habit	Evergreen Tree
Height	35.00 m
Growth Rate	Fast
Cultivation Status	Cultivated, Wild

Cultivation Details

Mansonia altissima is characteristic of the dense semi-deciduous forest in areas with about 1,600mm annual rainfall and a pronounced dry season. The southern limit of its distribution area largely corresponds with the transition of semi-deciduous forest to evergreen forest; to the north its distribution extends to patches of dense forest in the savannah[].
Seedlings are most common on fertile soils on drier sites; they are fairly drought resistant. During their first 2 years after germination, slight shade stimulates growth and the formation of healthy leaves. Leaves are held vertically in exposed conditions, more horizontally in the shade. After 2 years, however, the tree requires full sunlight and has been classified as a non-pioneer light demander[].
Seedlings attained a height of 1 - 2 metres within 4 years when growing in natural forest, and 6 metres in 4 years in logged areas. In Kumasi (Ghana) trees attained a bole diameter of 6.5 - 16cm and a height of 8 - 15 metres in 10 years[].
For plantations in Cameroon faster growth has been recorded, with trees growing 2 metres in height per year after 2 years decreasing to 1.3 metres per year after 10 years[].
In Côte d’Ivoire mean annual bole diameter growth of Mansonia altissima trees for all diameter classes was 2.5 - 7mm. Mean growth for the diameter class 30 - 50cm was 5.1mm per year. An average tree would reach a bole diameter of 50cm in 90 years[].
Freshly cut logs are usually too heavy to be transported by river[].

Edible Uses

None known

Medicinal

Products from the bark have been used in the treatment of leprosy. A bark extract is drunk or an infusion of the root is applied as enema as an aphrodisiac[].
A decoction of the twig bark is applied as a bath against yaws, scabies and syphilis[].

A root decoction is given as enema against leprosy[].

An ethanolic extract of the wood has shown hepatotoxic and haematotoxic effects when administered orally[].
Extracts of the bark have been shown to inhibit the growth of Mycobacterium tuberculosis[].
Because of its antibacterial properties, the addition of small amounts of bark to the diets of chicken, as a substitute of commercial antibiotics, improved feed conversion rates[].
The bark contains the highly toxic compound mansonine, related to cardenolides from Digitalis and ouabain from Strophanthus[]. Its aglycon was identified as strophanthidin. In addition some 30 toxic glycosides have been identified[].
From the wood similar glycosides, an azulene derivative, and a range of quinones, called mansonones A-I and L, have been isolated. Mansonone A is the main causal agent of the allergic reaction to the sawdust. The seeds too
contain a large number of cardenolide glycosides, including glycosides of strophanthidin and nigrescigenin. The glycosides strophothevoside and strophalloside are about as toxic to mammals as ouabain[].

Other Uses

The heartwood is yellowish brown to dark grey-brown or even dark brown, often with purple, reddish or greyish green streaks, often in alternating light and dark bands. It fades on exposure to a somewhat dull brown. It is distinctly demarcated from the 2 - 6cm wide band of white to pinkish sapwood. The grain is usually straight, texture fine, lustre moderate, without distinct odour or taste. The wood is of medium weight, moderately hard, very durable, being resistant to fungi, borers and termites It dries fairly rapidly with little distortion or degrade. The wood is easy to work with hand and machine tools with little or only moderate blunting effect on cutting edges and no charring; the surface can be worked to a good finish; the wood holds nails and screws fairly well, but iron tends to corrode in contact with it; gluing properties are good; the wood takes stain and polish well. The wood peels well, but requires softening beforehand; veneer is rather fragile. Steam-bending is easy unless knots are present. The wood is used for general and high-class joinery, cabinet work, furniture, turnery, decorative veneer and handicrafts. It is also used in construction for doors and windows, in railway coaches and shop fittings, and for boxes and crates. Well-coloured wood resembles American black walnut and is commonly used as a substitute for applications such as gun stocks and grips, musical instruments and loudspeaker enclosures[, , ].

Propagation

Seed - germination starts after about 10 days and may take one week, but a dormancy period of several months has also been observed[]. Dormancy caused little loss of seed viability. Germination occurs under both light and dark conditions, but is strongly depressedin large gaps in the forest[].

Add a Comment:

If you have any useful information about this plant, please leave a comment. Comments have to be approved before they are shown here.

Name:

Email(Private):

Message:

Captcha: what is greater, 5 or 9?