Douka
Tieghemella africana

Family: Sapotaceae

What it is like

Douka, Tieghemella africana, is a large tropical tree growing up to 50 m tall and 2.5 m across. It has an enormous crown and spreading, heavy branches. The bole is cylindrical and sometimes buttressed. The inner bark is fibrous and yields a sticky latex. The leaves are simple and alternate. The fruits are oval and contain one to three seeds each. The seeds yield fat which can be used externally to treat rheumatism. The yellowish and semi-fluid seed fat is edible and used as a cooking or seasoning oil. The wood is considered as one of the most durable African timbers because it is resistant to termites and fungal attacks. It is used for furniture, exterior and interior construction, flooring, doors, turnery, sculptures, veneer, plywood, etc.

Tieghemella africana is an evergreen Tree growing to 45 m (147ft) 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 can grow in full shade (deep woodland) semi-shade (light woodland) or no shade. It prefers moist soil.

Height (m): 45

Where it is found

An emergent tree of primary rain forest, most common in coastal lowland and diminishing towards the eastern parts of its range. It occurs scattered in the forest, but may locally be more abundant.

West tropical Africa - Cote D'Ivoire, Cameroon, Equatorial Guinea, Gabon, Congo, DR Congo.

Conservation Status: Status: Endangered A1cd

Countries/locations it is found in

Cameroon; Congo; Gabon; Sierra Leone, Africa, Cabinda, Central Africa, CAR, Central African Republic, Congo DR, Congo R, Equatorial Guinea,

How it is used

Food

Rating: 3

The seed kernels are rich in an edible fat, which is locally popular as a cooking or seasoning oil. The fatty oil from the seed kernel is yellowish and semi-fluid, has a pronounced flavour and taste, and consists of about 55% oleic acid, 21.5% stearic acid, 16.5% palmitic acid and 5% linoleic acid. The kernel comprises about 50% of fat.

Oil: Oil

Seed: includes nuts, cereals, peas and beans.

Medicine

Rating: 2

The fat obtained from the seeds is used externally to treat rheumatism.

Antirheumatic: Treats rheumatism.

Other

Rating: 4

Other Uses: The wood resembles African mahogany (Khaya and Entandrophragma spp.), but the texture is finer. The heartwood is pinkish-, purplish- or reddish-brown with a silky lustre, often with a decorative figure in the form of flames or stripes; it is very distinctly demarcated from the up to 8 cm wide band of pinkish white to greyish brown sapwood. The grain is straight or interlocked, texture fine and even. The wood is medium-weight; moderately hard; it is rated as one of the most durable African timbers, being resistant to termites and fungi although damage by pinhole borers and powder-post beetles has been recorded occasionally. Although it is resistant to marine borers in temperate waters, the wood is not very durable in tropical (especially brackish) waters. The wood is somewhat difficult to work due to the presence of silica - blunting effects are moderately severe when sawing, and stellite-tipped sawteeth are recommended; it finishes well, staining and polishing give good results; pre-boring for nailing and screwing is recommended to avoid splitting; gluing properties are good; the timber can be peeled satisfactorily. The heartwood is very difficult to impregnate, the sapwood moderately easy. Traded as makore or cherry mahogany, the wood is used for furniture, exterior and interior construction, flooring, doors, vehicle frames, sports goods, railway sleepers, turnery and sculptures. It makes a good and decorative veneer, often used to face plywood, especially for marine uses.

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

Oil: Vegetable oils have many uses, as lubricants, lighting, soap and paint making, waterproofing etc. This does not include the edible oils unless they are also mentioned as having other uses.

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

How it is grown

Douka is a plant of the lowland humid tropics. Young trees are tolerant of shade, but can survive in full sun. Trees have a moderately fast rate of growth. Young trees were on average 9 metres tall 6 years after planting in Gabon. The survival rate was about 90% and was almost equal when planted exposed to full sunlight in comparison with planting in the shade of forest cleared from undergrowth. The young trees grow faster when planted in light shade; 11-year-old trees were on average 18.5 metres tall and 13cm in diameter when planted in light shade, and 15.5 metres tall and 9cm in diameter in full sunlight. In a 66-year-old plantation in Gabon the mean annual increment is 0.4cm in diameter and 1.8 cubic metres per hectare in wood volume. The fruits are eaten by elephants, which are probably the main seed dispersers.

Propagating it: Seed - best sown as soon as it is ripe since the viability decreases rapidly once the seeds have been removed from the fruit. In the nursery, seeds are usually planted at a spacing of 40 cm _ 40 cm under light shade. Seedbeds should be watered well. Germination is over 90% in optimal conditions, and without pre-treatment. Germination begins after about 4 weeks, most seeds having germinated after 10 weeks, but it may continue for 16 weeks. Saplings of about 2.5 years old and 1 - 1.5 metres tall are planted out into the field usually at the beginning of the rainy season, but in western C?te d?Ivoire 0.5 year-old seedlings are used. The seeds are heavy, weighing 15 - 20g each. They should be planted within a few weeks because viability decreases rapidly.

Best place to grow:

Habit: Tree

Hardiness: 10-12

Growth: Fast

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

Shade: Full shade, semi-shade, no shade

Moisture: Moist

Things to keep in mind

Dust from sawn wood may cause irritation to skin and mucous membranes. It has been suggested that this is caused by the presence of saponins or the contact allergen 2,6-dimethoxy-1,4-benzoquinone. A highly haemolytic saponin has been isolated from the wood; on hydrolysis it gave d-glucose, l-rhamnose and d-xylose.

Its other names

Local names

Biadjo, N'duka, Nom adjap elang, Okola,

Synonyms

Baillonella africana (Pierre) Baehni Dumoria africana (Pierre) Dubard Lecomtedoxa vazii Dubard Mimus