Mansonia
Mansonia altissima

Family: Malvaceae

What it is like

Mansonia altissima is an evergreen tree growing up to 45 m in height and 100 cm in trunk diameter. It is grown throughout West tropical Africa. The crown is small, ovoid, and dense. The bole is straight and can be branchless for up to 30 m. Precautions should be taken when handling the bark because it is highly poisonous and may cause serious health problems. However, products from the bark are used in the treatment of leprosy. Twig bark decoction is applied as a bath for scabies, yaws, and syphilis. Root decoction, on the other hand, is used for leprosy as well. The wood is highly durable and moderately hard. It is resistant to fungi, borers, and termites.

Mansonia altissima is an evergreen Tree growing to 35 m (114ft) by 30 m (98ft) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 10. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers dry or moist soil and can tolerate drought.

Height (m): 35

Where it is found

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.

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

Conservation Status: This taxon has not yet been assessed

Countries/locations it is found in

Benin; Cameroon; Central African Republic; Congo; Côte d'Ivoire; Ghana; Guinea; Liberia; Nigeria; Togo

How it is used

Food

Rating: 0

Medicine

Rating: 2

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.

Antibacterial: Kills bacteria.

Antibiotic: An agent that inhibits or destroys a living organism. It usually refers to bacteria or other micro-organisms and is probably synonymous with Antibacterial

Aphrodisiac: Increases the sexual appetite.

Leprosy: Used to treat leprosy - a chronic bacterial infection of the skin and superficial nerves (in the skin) caused by Mycobacterium leprae.

Other

Rating: 4

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.

Furniture: A few miscellaneous uses that do not fit easily into other headings.

Wood: A list of the trees and shrubs that are noted for having useful wood.

How it is grown

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.

Propagating it: 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.

Best place to grow:

Habit: Tree

Hardiness: 10-12

Growth: Fast

Soil: Light (sandy), medium, heavy (clay)

Shade: No shade

Moisture: Dry, moist

Things to keep in mind

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.

Its other names

Local names

Mansonia

Synonyms

Achantia altissima A.Chev.