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Entandrophragma angolense (Welw.) C.DC.

Protologue
Bull. Herb. Boissier 2: 582, t. 21 (1894).
Family
Meliaceae
Chromosome number
2n = 36, 72
Synonyms
Entandrophragma macrophyllum A.Chev. (1909), Entandrophragma rederi Harms (1910), Entandrophragma leplaei Vermoesen (1921).
Vernacular names
Tiama mahogany (En). Tiama, acajou tiama (Fr). Kibaba da queta (Po).
Origin and geographic distribution
Entandrophragma angolense is widespread, occurring from Guinea east to southern Sudan, Uganda and western Kenya, and south to DR Congo and Angola.
Uses
The wood, usually traded as ‘gedu nohor’ or ‘tiama’, is highly valued for exterior and interior joinery, furniture, cabinet work, veneer and plywood, and is also used for flooring, interior trim, panelling, stairs, ship building, vehicle bodies and coffins. It is suitable for light construction, musical instruments, toys, novelties, boxes, crates, carvings and turnery. Wood that is not suitable as timber is used as firewood and for charcoal production.
The bark is used in traditional medicine. A decoction is drunk to treat fever and the bark is also used, usually in external applications, as an anodyne against stomach-ache and peptic ulcers, earache, and kidney, rheumatic or arthritic pains. It is also applied externally to treat ophthalmia, swellings and ulcers. The tree is planted as roadside tree, and occasionally as a shade tree in banana, coffee and tea plantations.
Production and international trade
In 2000 about 1000 m³ of Entandrophragma angolense timber was exported from Cameroon and 7500 m³ from Gabon, mainly to Europe. Congo exported 11,000 m³ of logs in 2004, at an average price of US$ 164/m³, and 8000 m³ in 2005, at an average price of US$ 143/m³. In 2005 Congo also exported 2000 m³ of sawn wood, at an average price of US$ 315/m³. Small amounts of veneer were exported from Congo in 2003 and 2004, at an average price of about US$ 300/m³. Entandrophragma angolense is one of the most valued timber species for export in Ghana.
Properties
The heartwood is pale pinkish brown to pale reddish brown, slightly darkening upon exposure to deep reddish brown, and distinctly demarcated from the creamy white to pale pinkish, up to 10 cm wide sapwood. The grain is interlocked, texture moderately coarse and fairly even. Quarter-sawn surfaces are irregularly striped.
The wood is medium-weight, with a density of 510–735 kg/m³ at 12% moisture content. It air dries slowly and is liable to warping and distortion. Mild schedules are needed for kiln drying. The rates of shrinkage are moderately high, from green to oven dry 3.8–6.6% radial and 5.8–9.6% tangential. The wood is usually moderately stable in service, but sometimes unstable; proper drying is needed before using the wood to avoid warping in service.
At 12% moisture content, the modulus of rupture is 69–132 N/mm², modulus of elasticity 7900–14,700 N/mm², compression parallel to grain 37–67 N/mm², shear 6–13 N/mm², cleavage 10–25 N/mm, Janka side hardness 4180–4220 N and Janka end hardness 5980–6000 N.
The wood saws and works easily with both hand and machine tools; it has only moderate blunting effects on cutting edges. In planing and moulding operations, a 15–20° cutting angle is recommended to avoid picking up of grain on quarter-sawn surfaces; back-sawn surfaces usually do not cause problems. Sharp cutters are needed for good finishing results. Drilling, mortising and turning properties are all satisfactory. The wood is not liable to splitting in nailing and screwing, with good holding properties. The gluing, staining and polishing properties are good, but the steam bending properties are poor. The wood is suitable for veneer production, both by rotary peeling as well as slicing; steaming for 48–72 hours at 85°C gives good results. The wood is moderately durable, being liable to powder-post beetle, pinhole borer and marine borer attacks and with variable resistance to termites. The heartwood does not take preservatives and even the sapwood is resistant to impregnation.
Methanol extracts of the bark showed dose-dependent inhibitory effects on gastric ulcers in tests with rats. The triterpenoid methyl angolensate, isolated from the bark, exerted inhibition of gastric ulceration and smooth muscle activity, and reduced the propulsive action of the gastrointestinal tract in mice. Methyl angolensate showed sedative activity in tests with mice and rats. Bark extracts showed moderate antiplasmodial activity; the compounds 7α-obacunylacetate and 24-methylenecycloartenol exhibited pronounced activity against chloroquine-resistant strains of Plasmodium falciparum. Tirucallane triterpenes have been isolated from a leaf extract.
The seeds have a fat content of about 60%. The fat is rich in cis-vaccenic acid, an oleic acid isomer that can be used in the industrial production of nylon-11. The approximate fatty acid composition of samples of the oil from Ghana and Nigeria is: palmitic acid 4–6%, palmitoleic acid 11–16%, hexadecadienoic acid 3–5%, stearic acid 10–15%, oleic acid 2–3%, vaccenic acid 32–43%, linoleic acid 11–15% and arachidic acid 1–2%. Tests with tadpoles showed that the seeds contain toxic compounds, probably limonoids.
Wood shavings of Entandrophragma angolense together with rice husk have been processed in a pressure vessel in the presence of aqueous sodium sulphide to produce a brilliant yellow dye of reasonable fastness to light and alkaline wash on cotton fabrics.
Description
Deciduous, dioecious large tree up to 50(–60) m tall; bole branchless for up to 30 (–40) m, usually straight and cylindrical, up to 200 cm in diameter, often with blunt buttresses up to 6 m high, often extending into surface roots; bark surface pale greyish brown to orange-brown, smooth but becoming scaly with irregular scales up to 20 cm in diameter leaving concave, often mussel-shell-shaped scars, inner bark pinkish red with whitish streaks, finely fibrous; crown dome-shaped; twigs glabrous, marked with large leaf scars and lenticels. Leaves alternate, clustered near ends of twigs, paripinnately compound with (8–)14–20(–22) leaflets; stipules absent; petiole 8–18 cm long, flattened or slightly channelled, often slightly winged at base, rachis 6–30 cm long; petiolules 1–6 mm long; leaflets opposite to alternate, oblong-elliptical to oblong-obovate, (3.5–)7–28 cm × (2–)3–8.5 cm, cuneate to nearly rounded at base, shortly acuminate and somewhat hooded at apex, thinly leathery, almost glabrous, pinnately veined with 6–12 pairs of lateral veins. Inflorescence an axillary or terminal panicle up to 40 cm long, short-hairy to nearly glabrous. Flowers unisexual, regular, 5-merous; pedicel 0.5–1.5 mm long; calyx cup-shaped, lobed to about the middle, 0.5–1 mm long, short-hairy on margins; petals free, oblong-elliptical, 4–5 mm long, glabrous, greenish white; stamens fused into a cup-shaped tube c. 4 mm long, with 10 anthers at the nearly entire apex; disk cushion-shaped; ovary superior, conical, 5-celled, style thick, slightly longer than stamens, stigma disk-shaped, with 5 lobes; male flowers with rudimentary ovary, female flowers with smaller, non-dehiscing anthers. Fruit a pendulous, cylindrical capsule 11–22 cm × 3–5 cm, brown to black, with many small lenticels, dehiscing from the base with 5 woody valves, many-seeded with seeds attached to the upper part of the central column. Seeds 6–9.5 cm long including the large apical wing. Seedling with epigeal germination, but cotyledons often remaining within the testa; hypocotyl 1.5–2.5 cm long, epicotyl 4–10 cm long; first 2 leaves opposite, simple.
Other botanical information
Entandrophragma comprises about 10 species and is confined to tropical Africa. It belongs to the tribe Swietenieae and is related to Lovoa, Khaya and Pseudocedrela.
Anatomy
Wood-anatomical description (IAWA hardwood codes):
Growth rings: (1: growth ring boundaries distinct); (2: growth ring boundaries indistinct or absent). Vessels: 5: wood diffuse-porous; (12: solitary vessel outline angular); 13: simple perforation plates; 22: intervessel pits alternate; (23: shape of alternate pits polygonal); 24: intervessel pits minute ( 4 μm); 30: vessel-ray pits with distinct borders; similar to intervessel pits in size and shape throughout the ray cell; 42: mean tangential diameter of vessel lumina 100–200 μm; 43: mean tangential diameter of vessel lumina 200 μm; 47: 5–20 vessels per square millimetre; 58: gums and other deposits in heartwood vessels. Tracheids and fibres: 61: fibres with simple to minutely bordered pits; 65: septate fibres present; 66: non-septate fibres present; 69: fibres thin-to thick-walled. Axial parenchyma: 78: axial parenchyma scanty paratracheal; 79: axial parenchyma vasicentric; (80: axial parenchyma aliform); (83: axial parenchyma confluent); (89: axial parenchyma in marginal or in seemingly marginal bands); 92: four (3–4) cells per parenchyma strand; 93: eight (5–8) cells per parenchyma strand; (94: over eight cells per parenchyma strand). Rays: 98: larger rays commonly 4- to 10-seriate; 106: body ray cells procumbent with one row of upright and/or square marginal cells; (107: body ray cells procumbent with mostly 2–4 rows of upright and/or square marginal cells); 115: 4–12 rays per mm. Storied structure: (122: rays and/or axial elements irregularly storied). Mineral inclusions: (136: prismatic crystals present); (137: prismatic crystals in upright and/or square ray cells); (138: prismatic crystals in procumbent ray cells); (141: prismatic crystals in non-chambered axial parenchyma cells).
(L.N. Banak, H. Beeckman & P.E. Gasson)
Growth and development
Under optimal conditions seedlings grow fairly fast, about 1 m/year during the first two years, exceptionally up to 2 m/year, and striplings may reach 6 m tall 4 years after planting. Under normal conditions, seedlings have a slower growth. They require shade, but after the seedling stage they should be gradually exposed to more light. In Nigeria seedlings reached only up to 3.1 m tall and 5 cm in stem diameter after 43 months, and in Guinea they reached the same size after 6 years. In Congo the mean annual growth during the first years is 50 cm in height and 7 mm in diameter. In a plantation in Gabon trees reached a mean diameter of 7.3 cm at 10 years old and in an arboretum only a 21.5 cm average diameter after 67 years; however, the 2 most vigorous trees in the arboretum reached 53 cm and 61 cm in diameter. Larger trees showed average annual diameter increments of 2–6.5 mm, with highest increment in the diameter class of 50–70 cm when the crown reached the forest canopy. In Nigeria it has been estimated that it takes nearly 140 years for a planted tree to reach 100 cm bole diameter, and in Gabon it has been estimated that it takes 70 years to reach 40 cm in diameter under adequate silvicultural treatment. Trees start fruit production at larger diameters, and this has implications for forest management; harvesting trees of less than 50 cm bole diameter seriously reduces fruit production.
In Liberia Entandrophragma angolense trees are deciduous for a short period at the beginning of the dry season. Flowering occurs near the middle of the dry season, around February. In Côte d’Ivoire trees flower from December to February, sometimes to April. In Ghana flowering has been reported to occur in December, together with new leaves. Fruits mature about 8 months after flowering. In Congo fruits ripen in May–July and in Guinea in September–February. Ripe fruits may fall unopened under conditions of lasting high air humidity. However, under lower humidity they open on the tree and the seeds are dispersed by wind, although most seeds seem to fall close to the mother tree.
Ecology
In West Africa Entandrophragma angolense is most common in moist semi-deciduous forest, particularly in regions with an annual rainfall of 1600–1800 mm. However, it can also be found in evergreen forest, but its abundance strongly declines in regions with an annual rainfall of more than 2300 mm. In East Africa it occurs in lowland and mid-altitude rainforest, but sometimes also in gallery forest and thickets, up to 1800 m altitude. It strongly prefers well-drained localities with good water-holding capacity.
Natural regeneration is often scarce in natural forest, but logging operations that create gaps may promote regeneration. In natural forest, saplings are most common in gaps. Tests with seedlings showed that growth was good under conditions simulating the light conditions in small forest gaps, and that growth was still fair under the light conditions of medium-sized gaps. The seedlings performed poorly under full-light conditions.
Propagation and planting
The 1000-seed weight is 300–500 g. Seeds can be stored for some time in sealed containers in a cool place, but insect damage, to which they are very susceptible, should be avoided, e.g. by adding ash. Fresh seeds may have a high germination rate, more than 75%, but the germination rate decreases to about 25% after 3 weeks storage in open air. Germination of fresh seeds starts 1 week after sowing, but germination of seeds stored for 10–15 days may take 30–45 days. Soaking of the seeds for one night is reported to speed up germination. Seeds should be placed in seed beds with the wing pointing upward and ¾ of the seed (without wing) buried. Overhead shade is required for young seedlings.
It is recommended to plant out under a light cover of a young secondary forest or in enrichment lines in forest paths. Clearing is necessary after 3–4 years. It is possible to plant in full sun on exceptionally fertile soils or on dead termite nests but the mortality may be as high as 50% after some years.
Management
In drier types of forest in eastern Liberia, the average density of Entandrophragma angolense trees of more than 60 cm bole diameter was 1 per 20 ha, in evergreen forest 1 per 34 ha. In southern Cameroon the average density is one tree of more than 60 cm bole diameter per 15–30 ha, and the average wood volume is up to 0.55 m³/ha. In Gabon the trees occur widely scattered, with an average wood volume of only 0.05 m³/ha. Forest exploitation enhances natural regeneration, not only through germination of seeds but also through sprouting of coppices.
Harvesting
Minimum felling diameters are 60 cm in Côte d’Ivoire, 80 cm in Cameroon, the Central African Republic, Gabon and Congo, 90 cm in Liberia, and 110 cm in Ghana. The presence of large buttresses in big trees often necessitates the construction of a platform before felling of the bole can take place, or cutting off the buttresses before felling.
Yield
On average a tree 60 cm in diameter yields 3.7–4.4 m³ of commercial timber, a tree 1 m in diameter 10.2–11.8 m³ and a tree 1.5 m in diameter 23–30 m³.
Handling after harvest
Logs float in water and can thus be transported by river.
Genetic resources
Although Entandrophragma angolense is widely distributed, it may become liable to genetic erosion in the near future. The commercial interest in its timber has resulted in extraction of large individuals from the forest throughout the distribution area. In Ghana and Uganda Entandrophragma angolense is considered threatened. It is included in the IUCN Red list as vulnerable.
Prospects
In many regions Entandrophragma angolense is not exploited on a sustainable basis at present. The rather low growth rates under natural conditions, the long time needed to reach maturity in terms of fruit production and poor dispersal of the seed seem to be serious drawbacks to regeneration. On the other hand, Entandrophragma angolense is capable of fair regeneration in logged-over forest. More research is needed on appropriate management measures such as sowing of seeds in suitable localities in logged-over forest. Rotation cycles needed to ensure sustainable exploitation in natural forest are probably comparatively long.
The seeds are a rich source of oil from a quantitative point of view, but toxicity studies and more detailed studies on the oil properties are still needed.
Major references
• Aubréville, A., 1959. La flore forestière de la Côte d’Ivoire. Deuxième édition révisée. Tome deuxième. Publication No 15. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 341 pp.
• Bolza, E. & Keating, W.G., 1972. African timbers: the properties, uses and characteristics of 700 species. Division of Building Research, CSIRO, Melbourne, Australia. 710 pp.
• Burkill, H.M., 1997. The useful plants of West Tropical Africa. 2nd Edition. Volume 4, Families M–R. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 969 pp.
• Farmer, R.H., 1972. Handbook of hardwoods. 2nd Edition. Her Majesty’s Stationery Office, London, United Kingdom. 243 pp.
• Katende, A.B., Birnie, A. & Tengnäs, B., 1995. Useful trees and shrubs for Uganda: identification, propagation and management for agricultural and pastoral communities. Technical Handbook 10. Regional Soil Conservation Unit, Nairobi, Kenya. 710 pp.
• Normand, D. & Paquis, J., 1976. Manuel d’identification des bois commerciaux. Tome 2. Afrique guinéo-congolaise. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 335 pp.
• Styles, B.T. & White, F., 1991. Meliaceae. In: Polhill, R.M. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. 68 pp.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan, 248 pp.
• Vivien, J. & Faure, J.J., 1985. Arbres des forêts denses d’Afrique Centrale. Agence de Coopération Culturelle et Technique, Paris, France. 565 pp.
• Voorhoeve, A.G., 1979. Liberian high forest trees. A systematic botanical study of the 75 most important or frequent high forest trees, with reference to numerous related species. Agricultural Research Reports 652, 2nd Impression. Centre for Agricultural Publishing and Documentation, Wageningen, Netherlands. 416 pp.
Other references
• Amos, S., Orisadipe, A., Binda, L., Emeje, M., Adesomoju, A., Okogun, J., Akah, P., Wambebe, C. & Gamaniel, K., 2002. Behavioural effects in rodents of methyl angolensate: a triterpenoid isolated from Entandrophragma angolense. Pharmacology and Toxicology 91(2): 71–76.
• Asiamah, I., 2000. Chemical constituents of the seeds of Entandrophragma angolense. B.Sc. Chemistry degree thesis, Department of Chemistry, Faculty of Science, University of Cape Coast, Cape Coast, Ghana. 36 pp.
• ATIBT (Association Technique Internationale des Bois Tropicaux), 1986. Tropical timber atlas: Part 1 – Africa. ATIBT, Paris, France. 208 pp.
• Bickii, J., Tchouya, G.R.F., Tchouankeu, J.C. & Tsamo, E., 2007. The antiplasmodial agents of the stem bark of Entandrophragma angolense (Meliaceae). African Journal of Traditional, Complementary and Alternative Medicines 4(2): 135–139.
• CIRAD Forestry Department, 2003. Tiama. [Internet] Tropix 5.0. http://tropix.cirad.fr/ africa/kosipo.pdf. Accessed March 2008.
• CTFT (Centre Technique Forestier Tropical), 1948. Tiama. Bois et Forêts des Tropiques 8: 395–398.
• de Saint-Aubin, G., 1963. La forêt du Gabon. Publication No 21 du Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 208 pp.
• Dupuy, B., 1998. Bases pour une sylviculture en forêt dense tropicale humide africaine. Document Forafri 4. Cirad, Montpellier, France. 328 pp.
• Ezeagu, I.E., Petzke, K.J., Lange, E. & Metges, C.C., 1998. Fat content and fatty acid composition of oils extracted from selected wild-gathered tropical plant seeds from Nigeria. Journal of the American Oil Chemists’ Society 75(8): 1031–1035.
• Lean Teik Ng & Su Foong Yap, 2003. Gynura Cass. In: Lemmens, R.H.M.J. & Bunyapraphatsara, N. (Editors). Plant Resources of South-East Asia No 12(3). Medicinal and poisonous plants 3. Backhuys Publishers, Leiden, Netherlands. pp. 231–233.
• Hawthorne, W. & Jongkind, C., 2006. Woody plants of western African forests: a guide to the forest trees, shrubs and lianes from Senegal to Ghana. Kew Publishing, Royal Botanic Gardens, Kew, United Kingdom. 1023 pp.
• InsideWood, undated. [Internet] http://insidewood.lib.ncsu.edu/search/. Accessed May 2007.
• Kleiman, R. & Payne-Wahl, K.L., 1984. Fatty acid composition of seed oils of the Meliaceae, including one genus rich in cis-vaccenic acid. Journal of the American Oil Chemists Society 61(12): 1836–1838.
• Muteeba, T., 2000. An assessment of regeneration of Entandrophragma angolense in the exploited areas of Mugoye Forest Reserve, Kalangala District. B.Sc. Forestry Project Report, Faculty of Forestry and Nature Conservation, Makerere University, Kampala, Uganda. 81 pp.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
• Njar, V.C.O., Adesanwo, J.K., Makinde, J.M. & Taiwo, O.B., 1994. Antiulcer activity of the stem bark extract of Entandrophragma angolense. Phytotherapy Research 8(1): 46–48.
• Orisadipe, A., Amos, S., Adesomoju, A., Binda, L., Emeje, M., Okogun, J., Wambebe, C. & Gamaniel, K., 2001. Spasmolytic activity of methyl angolensate: a triterpenoid isolated from Entandrophragma angolense. Biological and Pharmaceutical Bulletin 24(4): 364–367.
• Oteng-Amoako, A.A. (Editor), 2006. 100 tropical African timber trees from Ghana: tree description and wood identification with notes on distribution, ecology, silviculture, ethnobotany and wood uses. 304 pp.
• Parant, B., Boyer, F., Chichignoud, M. & Curie, P., 2008. Présentation graphique des caractères technologiques des principaux bois tropicaux. Tome 1. Bois d’Afrique. Réédition. CIRAD-Fôret, Montpellier, France. 186 pp.
• Siepel, A., Poorter, L. & Hawthorne, W.D., 2004. Ecological profiles of large timber species. In: Poorter, L., Bongers, F., Kouamé, F.N. & Hawthorne, W.D. (Editors). Biodiversity of West African forests. An ecological atlas of woody plant species. CABI Publishing, CAB International, Wallingford, United Kingdom. pp. 391–445.
• Tailfer, Y., 1989. La forêt dense d’Afrique centrale. Identification pratique des principaux arbres. Tome 2. CTA, Wageningen, Pays Bas. pp. 465–1271.
Sources of illustration
• Voorhoeve, A.G., 1979. Liberian high forest trees. A systematic botanical study of the 75 most important or frequent high forest trees, with reference to numerous related species. Agricultural Research Reports 652, 2nd Impression. Centre for Agricultural Publishing and Documentation, Wageningen, Netherlands. 416 pp.
• Wilks, C. & Issembé, Y., 2000. Les arbres de la Guinée Equatoriale: Guide pratique d’identification: région continentale. Projet CUREF, Bata, Guinée Equatoriale. 546 pp.
Author(s)
A.T. Tchinda
Institut de Recherches Médicales et d’Etudes des Plantes Médicinales (IMPM), Ministère de la Recherche Scientifique et de l’Innovation, B.P. 6163, Yaoundé, Cameroun


Editors
D. Louppe
CIRAD, Département Environnements et Sociétés, Cirad es-dir, Campus international de Baillarguet, TA C-DIR / B (Bât. C, Bur. 113), 34398 Montpellier Cedex 5, France
A.A. Oteng-Amoako
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
General editors
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
L.P.A. Oyen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
J.R. Cobbinah
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
Photo editor
G.H. Schmelzer
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article:
Tchinda, A.T., 2008. Entandrophragma angolense (Welw.) C.DC. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.

















































Distribution Map wild


1, base of bole; 2, flowering twig; 3, dehisced fruit with one valve removed.
Redrawn and adapted by Iskak Syamsudin



tree habit


bole


base of bole


bark


slash


slash


leaves, fruits and seeds


seedling


various parts of the tree
obtained from W.D. Hawthorne



wood


wood in transverse section


wood in tangential section


wood in radial section


transverse surface of wood