Common Name: African Coralwood

General Information

Pterocarpus soyauxii is an evergreen or briefly deciduous tree with an open, dome-shaped crown; it can grow 30 - 50 metres tall[, ]. The straight and cylindrical bole is up to 1.4 metres in diameter[]. It can be free of branches for up to 32 metres, though it sometimes has sharp buttresses 3 - 4 metres high and 2 metres broad at the base[].
A multipurpose tree, providing edible leaves, medicine, timber and dyes for the local population. The valuable heartwood is exported, mainly from Cameroon and Gabon, mainly as a timber but formerly also as a dye stuff[]. The tree is sometimes planted in the villages, especially in S Nigeria, in order to provide edible leaves[].

Known Hazards

The dry sawdust may cause irritation to skin, nose and bronchi[].

Botanical References

Range

West tropical Africa - Nigeria, Cameroon, Central African Republic, Equatorial Guinea, Gabon, Zaire and Angola.

Habitat

Evergreen or deciduous forests on firm-ground, rain-forest; at elevations from 50 - 500 metres[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Semi-deciduous Tree
Height	40.00 m
Pollinators	Insects
Cultivation Status	Cultivated, Wild

Cultivation Details

A plant of the lowland wet tropics, where it is found at elevations up to 500 metres. It grows best in areas where the mean annual temperature is about 23°c[]. It prefers a mean annual rainfall of 1,500 - 1,700mm[, ].
Requires a sunny position[, ]. Prefers a moist but well-drained deep soil[, ].
Seedling growth is rather fast. In a trial plantation in Cote d'Ivoire, annual height growth in the first 7 years varied between 1.6 metres and 2.7 metres[].
Trees do not coppice well, stump regrowth is weak and uneconomic for wood production[, ].
This species is one of several that supply a red resin from their stem. This resin, often known as 'Dragon's Blood' is often used as an external application to treat a range of skin problems and injuries[]. Dragon's Blood can be obtained from several species in this genus, as well as from three other distinct genera - Dracaena species, Croton species and Daemonorops species[]
This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[].

Edible Uses

Leaves and young shoots - cooked as a vegetable, made into soups, or used for other dishes with cassava and yam[, ]. A popular and commonly used vegetable in southeastern Nigeria, valued for its unique taste and high vitamin C content. A high ascorbic acid content, even after cooking[].

Medicinal

The powdered wood, baked with a slice of lime, is used as a dressing on wounds[]. Mixed with palm oil, raffia oil or vegetable butter, it is used to treat skin diseases, ringworm and yaws[].

The bark contains a kino type resin, known as 'dragon's blood'[]. This is very astringent and is used to ward off skin parasites in ethnoveterinary medicine. It is also used, usually in combinations with parts of other plants, as an enema to treat dysentery and against toothache, gonorrhoea and excessive menstruation[].

A bark decoction is drunk to treat dysmenorrhoea, uterine haemorrhage, dysentery and haemorrhoids[].
A pulp obtained by scraping the inner surface of the bark is applied as a wet dressing against inflammations, oedemas, incipient hernia and whitlow[].
Decoctions, draughts or vapour-baths of the leaves and bark are taken against broncho-pulmonary affections[].

In trials, the bark showed antifungal activity against some pathogenic fungi[].

Other Uses

A red dye is obtained from the heartwood[]. The source of the so-called true barwood dye, it is used to colour fibres and cloth; in cosmetics and in magical rites and ceremonies[, ]. More recently it has been used in Europe as a food colouring for ketchup[]. The dye is combined with tannin-rich plants and a mordant of iron-rich mud to produce the famous 'Kasai velvet' dyes of Zaire[].
A pomade, made by mixing the red wood powder with oil, is used as a body cosmetic[]. The roots can be prepared and used in the same way as the heartwood and yield a dye of equal or better quality[]. Pulverized bark, mixed with palm oil, is also used as a cosmetic pomade[].
Logs are liable to brittle heart. For dye extraction, preferably old and hollow trees are cut from the forest and the heartwood is lumbered out. Often trees are felled and left for 2 - 3 years lying on the forest floor before taking the heartwood for dyeing purposes[]. The roots are also harvested for dye extraction[].
For dye production the heartwood is split into billets and chips which are dried and subsequently pounded into powder. A little oil is added to the pulverized material, which is moulded into cakes for stocking and for local sale[].

An extract of the wood is used as an astringent in commercial cosmetic preparations[]

The heartwood is bright red when freshly cut, becoming orange-red on exposure and darkening to purple-brown; it is distinctly demarcated from the 6 0 20cm wide band of whitish to brownish yellow sapwood. The grain is straight to interlocked; the texture coarse; the wood has a faint aromatic scent when freshly cut. The wood is moderately heavy to heavy; hard to very hard; very durable being resistant to fungi, Lyctus beetles, termites and marine borers. It seasons somewhat slowly, but with only a slight risk of checking and distortion; once dry it is stable in service. It is moderately difficult to work, having a fairly high blunting effect - stellite-tipped sawteeth and tungsten carbide cutting tools are recommended; it takes a good finish, but sometimes with some tearing of interlocked grain; slicing does not cause problems; nailing and screwing are good, but pre-boring is advisable; gluing properties are good. A valuable multipurpose hardwood, because of its resistance to water it is used locally to make canoes and because of its beautiful reddish colour it is favoured for carving and sculpturing, high class furniture, cabinet making, knife and tool handles, traditional hair combs, walking sticks and musical instruments. The wood has a high resonance quality as its damping of vibrations is low - in the past large telegraph slit drums and war drums, as well as xylophones, have been made from it. It is currently used also for ‘Western music’ xylophones and increasingly tried for the back and sides of guitars. Because of its high durability the wood is excellent for construction, carpentry, outdoor joinery, flooring, staircases, railway sleepers and boats but also for veneer, inlay, billiard tables, toys, joinery, dowels, shuttles, bobbins, spindles, sporting goods and paddles. As the wood is resistant to marine borers it was used in temperate regions for marine constructions such as piers and sluice gates[, ].
The wood is also used as fuel[].

Propagation

Seed - an easy process[]. In a test in Nigeria, 86% of the seeds, with the fruit wall removed, were soaked overnight in water and then germinated in 7 days[]. Seedlings can be planted out into the field about 40 days after sowing[]. Seedling growth showed a greater response after inoculation of the soil with fungi from the rhizosphere of the mother tree than after inoculation with a similar spore number of fungi from a fallow field[].
Propagation by non-woody cuttings in normal topsoil gave 83% success[].

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