Oldfieldia africana (PROTA)

Plant Resources of Tropical Africa Introduction

List of species

General importance
Geographic coverage Africa
Geographic coverage World
Medicinal
Timber

Oldfieldia africana Benth. & Hook.f.

Protologue: Hooker’s Journ. Bot. Kew Gard. Misc. 2: 185 (1850).

Family: Euphorbiaceae (APG: Picrodendraceae)

Vernacular names

African oak, turtosa (En). Chêne d’Afrique (Fr).

Origin and geographic distribution

Oldfieldia africana occurs from Guinea and Sierra Leone to western Côte d’Ivoire and also in Cameroon; possibly in the Central African Republic and Gabon.

Uses

The brown or reddish brown wood, known in trade as ‘African oak’, is used for bridge construction and bridge decks, ship building and ship yards. It is suitable for heavy construction and flooring, joinery, interior trim, mine props, vehicle bodies, furniture, cabinet work, sporting goods, toys, novelties, musical instruments, ladders, agricultural implements, handles, carvings, vats, turnery, draining boards and pattern making.

In traditional medicine in Côte d’Ivoire, pounded leaves are applied as an antiseptic and haemostatic to wounds. Powdered twig bark is applied to wounds to promote healing and against kidney pain, whereas a maceration of twig bark in palm wine is drunk as an aphrodisiac. In Liberia bark decoctions are added to medicines used as pelvic decongestant against gonorrhoea. In Sierra Leone the leaves are used to repel bees and flies, and in Liberia pounded seeds and bark are used as insecticide.

Production and international trade

The wood of Oldfieldia africana was probably one of the first woods traded from tropical West Africa to Europe. Already in the 18^th century it was imported in Britain as a substitute for oak for ship building. It is still traded internationally, but in small volumes only.

Properties

The heartwood is dark red-brown, often with a purplish tinge and fairly distinctly demarcated from the pale red, 4–6 cm wide sapwood. The grain is straight to slightly interlocked or wavy, texture fine and even. The wood is similar to oak in appearance, but stronger and more resistant to compression. It is heavy to very heavy, with a density of 870–1060 kg/m³ at 12% moisture content. It air dries fairly well, without much distortion and with few end checks. Boards of 2.5 cm thick air dry to 20% moisture content in about 6 weeks. However, boards of 5 cm thick showed numerous surface checks after drying. The shrinkage rates are moderately high, from green to oven dry about 6.2% radial and 10.0% tangential. Once dry, the wood is moderately stable in service. At 12% moisture content the modulus of rupture is 163–176 N/mm², modulus of elasticity 18,100–22,700 N/mm², compression parallel to grain 84 N/mm², shear 16 N/mm² and Janka side hardness 12,600 N.

The wood is somewhat difficult to work with both hand and machine tools because of its high density. It saws and planes slowly but well. It polishes to a smooth surface. Much force is needed for nailing and screwing, but the wood holds nails and screws well. The wood stains in contact with iron. It is not suitable for veneer production, but it turns very well. The wood is very durable and only rarely attacked by marine borers or termites, but occasionally by pinhole borers. The heartwood is resistant to impregnation with preservatives. The wood contains 2.4% ash and 0.02% silica.

Description

Evergreen or short-deciduous, dioecious, medium-sized to fairly large tree up to 40 m tall; bole straight and cylindrical, up to 20 m long, up to 120(–150) cm in diameter, with root swellings at base, sometimes extending into swollen surface roots; bark surface vertically fissured, thin scaly, yellowish brown, inner bark rough fibrous, brittle, brown with lighter and darker stripes, paler inside, bitter; crown rather narrow, with heavy, ascending branches; twigs rusty-brown hairy, becoming glabrous and with marked leaf-scars when older. Leaves opposite, digitately compound with (3–)5–8(–9) leaflets; stipules absent; petiole up to 10 cm long, broadened at apex; petiolules c. 0.5 cm long, grooved above; leaflets oblanceolate to elliptical, 4–17.5 cm × 1.5–6.5 cm, central leaflet largest, cuneate at base, acuminate at apex, margins entire, leathery, glabrous, pinnately veined with 6–15 pairs of lateral veins. Inflorescence a lax, axillary cyme up to 6 cm long, brown hairy, male one with many-flowered, female 2–3-flowered. Flowers unisexual, regular, small, calyx short-hairy, with 5–7 short lobes, petals absent; male flowers with pedicel 0.5–4 mm long, calyx tube c. 0.5 mm long, stamens (2–)5–10, free, disk rounded, hairy; female flowers with larger calyx, ovary superior, (2–)3(–4)-celled. Fruit an ovoid-globose capsule 2–2.5 cm long, orange when ripe, dehiscent with usually 3 leathery to woody valves, few-seeded. Seeds obliquely obovoid, c. 1 cm long, slightly flattened, orange when ripe. Seedling with epigeal germination; hypocotyl 5–9 cm long, epicotyl 0.5–1 cm long, hairy; cotyledons leafy, broadly obovate to nearly round, c. 2.5 cm in diameter; first leaves alternate and often simple, later ones opposite and compound.

Other botanical information

Oldfieldia comprises 4 species, all occurring in continental tropical Africa.

Oldfieldia dactylophylla

Oldfieldia dactylophylla (Welw. ex Oliv.) J.Léonard (synonym: Paivaeusa dactylophylla Welw. ex Oliv.) is a much-branched small tree up to 15 m tall, with a short straight bole up to 25 cm in diameter, occurring in woodland in DR Congo, Tanzania, Malawi, Zambia and Angola. Its wood is used for construction in house building, for utensils such as spoons, and as firewood. The fruit pulp is edible. Root decoctions are administered to treat sexually transmitted diseases and hernia, and as aphrodisiac.

Oldfieldia somalensis

Oldfieldia somalensis (Chiov.) Milne-Redh., called ‘mbauri’ or ‘mbambara’ in Swahili, is an evergreen, much-branched, small to medium-sized tree up to 20 m tall, occurring in lowland dry forest and woodland in coastal regions from Somalia through Kenya and Tanzania to Mozambique. Its wood is used for construction, door frames, utensils, mortars and carvings, and as firewood. Root decoctions are taken to treat chest complaints and sterility. The bark is bitter and poisonous, but is used in Tanzania as medicine against pneumonia. The tree is poisonous to livestock.

Oldfieldia macrocarpa

Oldfieldia macrocarpa J.Léonard is a very poorly known, medium-sized to fairly large tree up to 40 m tall with a straight bole branchless for up to 25 m and up to 100 cm in diameter, occurring in rainforest in DR Congo. It has beautiful pinkish brown to reddish brown wood that may become more important in trade if sufficient stands are available.

Anatomy

Wood-anatomical description (IAWA hardwood codes):

• Growth rings: 2: growth ring boundaries indistinct or absent.
• Vessels: 5: wood diffuse-porous; 13: simple perforation plates; 22: intervessel pits alternate; (23: shape of alternate pits polygonal); 25: intervessel pits small (4–7 μm); 26: intervessel pits medium (7–10 μm); 30: vessel-ray pits with distinct borders; similar to intervessel pits in size and shape throughout the ray cell; 41: mean tangential diameter of vessel lumina 50–100 μm; 48: 20–40 vessels per square millimetre; (49: 40–100 vessels per square millimetre); 58: gums and other deposits in heartwood vessels.
• Tracheids and fibres: 61: fibres with simple to minutely bordered pits; 66: non-septate fibres present; 70: fibres very thick-walled.
• Axial parenchyma: 76: axial parenchyma diffuse; 77: axial parenchyma diffuse-in-aggregates; (78: axial parenchyma scanty paratracheal); (86: axial parenchyma in narrow bands or lines up to three cells wide); 93: eight (5–8) cells per parenchyma strand; 94: over eight cells per parenchyma strand.
• Rays: 97: ray width 1–3 cells; 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; (113: disjunctive ray parenchyma cell walls present); 115: 4–12 rays per mm.
• Mineral inclusions: (136: prismatic crystals present); (142: prismatic crystals in chambered axial parenchyma cells).

(P. Mugabi, P.E. Gasson & E.A. Wheeler)

Growth and development

After transplanting, seedlings grow up to 20 cm in 1 month, and up to 45 cm in 8 months. In Guinea 1-year-old seedlings planted in full sun reached 2.7 m in height 4 years after planting, but the mortality was 33%. Seedlings planted with lateral shade showed a lower mortality rate of 20%. Trees do not lose their leaves in evergreen forest, but are deciduous for a short period in semi-deciduous forest. In Liberia and Côte d’Ivoire, new pale reddish brown leaves appear together with the inflorescences in March–May; fruits are found from June to February. Oldfieldia africana regenerates readily and is fairly tolerant of shade in the sapling stage.

Ecology

Oldfieldia africana in evergreen and moist semi-deciduous rainforest, occasionally in secondary forest, usually on well-drained soils and not in swampy locations.

Propagation and planting

The seeds are difficult to collect as they are rich in oil and readily eaten by monkeys and other animals. They lose viability quickly upon storage. There are 4000–5000 seeds per kg. In a test in Sierra Leone, seeds germinated in 4.5–7 weeks and had a germination rate of 40%. In Côte d’Ivoire seeds started germinating 3–4.5 weeks after sowing and had a high germination rate. In Guinea the germination rate was 17–97% in 2–4 weeks, depending on the freshness of the seeds; seeds sown immediately after collection showed best results. It is recommended to plant seedlings into the field when they are about 1 year old.

Management

Oldfieldia africana occurs scattered or in small groups in the forest. It is rarely common, but locally in Sierra Leone on average 0.35 trees with a bole diameter of more than 60 cm can be found per ha. No attempts have been made to manage natural stands or to plant it in in forest plantations. Small-scale planting experiments showed that weeding is essential to reduce competition for a period of 3–4 years after planting.

Handling after harvest

Logs are very heavy and cannot be transported by rivers.

Genetic resources

Although Oldfieldia africana occurs in a fairly small area and largely in heavily exploited rainforest, it is not included in the IUCN Red list of endangered species. In Cameroon it is considered vulnerable, but probably it should be considered as such in its whole distribution area because it is quite uncommon and mainly found in primary forest.

Prospects

The wood of Oldfieldia africana is likely to remain in demand on international and local markets, but it is available in small quantities only. It is unlikely that this situation will change. The pharmacological properties deserve research attention.

Major references

• Adjanohoun, E.J. & Aké Assi, L., 1979. Contribution au recensement des plantes médicinales de Côte d’Ivoire. Centre National de Floristique, Abidjan, Côte d’Ivoire. 358 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., 1994. The useful plants of West Tropical Africa. 2nd Edition. Volume 2, Families E–I. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 636 pp.

• Dudek, S., Förster, B. & Klissenbauer, K., 1981. Lesser known Liberian timber species. Description of physical and mechanical properties, natural durability, treatability, workability and suggested uses. GTZ, Eschborn, Germany. 168 pp.

• Ilic, J., 1991. CSIRO atlas of hardwoods. Crawford House Press, Bathurst & CSIRO, Melbourne, Australia and Springer-Verlag, Berlin, Germany. 525 pp.

• Keay, R.W.J., 1958. Euphorbiaceae. In: Keay, R.W.J. (Editor). Flora of West Tropical Africa. Volume 1, part 2. 2nd Edition. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. pp. 364–423.

• Léonard, J., 1956. Notulae Systematicae XXI. Observations sur les genres Oldfieldia, Paivaeusa et Cecchia (Euphorbiaceae africanae). Bulletin du Jardin botanique de l’État à Bruxelles 26(4) : 335–343.

• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.

• Savill, P.S. & Fox, J.E.D., 1967. Trees of Sierra Leone. Forest Department, Freetown, Sierra Leone. 316 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

• 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.

• Betti, J.L., 2002. Medicinal plants sold in Yaoundé markets, Cameroon. African Study Monographs 23(2): 47–64.

• Bouquet, A. & Debray, M., 1974. Plantes médicinales de la Côte d’Ivoire. Travaux et Documents No 32. ORSTOM, Paris, France. 231 pp.

• Chilima, C.Z. & Namoto, M., 2008. The collection and long term storage of Oldfieldia dactylophylla ‘Nawonga’ seeds; an endangered wild plant species in Malawi. FRIM (Malawi) Newsletter 94: 2.

• Chilufya, H. & Tengnäs, B., 1996. Agroforestry extension manual for northern Zambia. Regional Soil Conservation Unit, Nairobi, Kenya. 120 + 124 pp.

• de la Mensbruge, G., 1966. La germination et les plantules des essences arborées de la forêt dense humide de la Côte d’Ivoire. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 389 pp.

• Dery, B.B., Otsyina, R. & Ng'atigwa, C. (Editors), 1999. Indigenous knowledge of medicinal trees and setting priorities for their domestication in Shinyanga Region, Tanzania. ICRAF, Nairobi, Kenya. 98 pp.

• FAO, 1985. In situ conservation of forest genetic resources in Cameroon. [Internet] Forest Genetic Resources Information No. 14. http://www.fao.org/DOCREP/006/R4968E/R4968E07.htm#ref7.1. February 2012.

• Hubert, D., undated. Sylviculture des essences de forêts denses humides d’Afrique de l’Ouest. 187 pp.

• Jansen, J.W.A., 1974. Timber trees of Liberia. [Internet] FAO, Rome, Italy. ftp://ftp.fao.org/ docrep/fao/008/ae893e/ ae893e00.pdf. February 2012.

• Kryn, J.M. & Fobes, E.W., 1959. The woods of Liberia. Report 2159. USDA Forest Service, Forest Products Laboratory, Madison, Wisconsin, United States. 147 pp.

• Lovett, J.C., Ruffo, C.K., Gereau, R.E. & Taplin, J.R.D., 2007. Field Guide to the moist forest trees of Tanzania. Frontier Publishing, United Kingdom. 303 pp.

• Méniaud, J. & Bretonnet, F., 1926. Les bois coloniaux d’Afrique dans l’industrie. Imprimerie administrative, Melun, France. 125 pp.

• Normand, D., 1955. Atlas des bois de la Côte d’Ivoire. Tome 2. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 132 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.

• Radcliffe-Smith, A., 1987. Segregate families from the Euphorbiaceae. Botanical Journal of the Linnean Society 94: 47–66.

• Ruffo, C.K., Birnie, A. & Tengnäs, B., 2002. Edible wild plants of Tanzania. Technical Handbook No 27. Regional Land Management Unit/ SIDA, Nairobi, Kenya. 766 pp.

• Tailfer, Y., 1989. La forêt dense d’Afrique centrale. Identification pratique des principaux arbres. Tome 2. CTA, Wageningen, Pays-Bas. pp. 465–1271.

• Torelli, N., Piškur, M. & Tišler, V., 2003. Wood species of the Central African Republic: ash and silica content. [Internet] Zbornik Gozdarstva in Lesarstva 72: 53–61. http://www.gozdis.si/ zbgl/2003/ zbgl-72–3.pdf. February 2012.

• Vivien, J. & Faure, J.J., 1985. Arbres des forêts denses d’Afrique Centrale. Agence de Coopération Culturelle et Technique, Paris, France. 565 pp.

Sources of illustration

• Akoègninou, A., van der Burg, W.J. & van der Maesen, L.J.G. (Editors), 2006. Flore analytique du Bénin. Backhuys Publishers, Leiden, Netherlands. 1034 pp.

Author(s)

• L.P.A. Oyen, PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article

Oyen, L.P.A., 2012. Oldfieldia africana Benth. & Hook.f. In: Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. Accessed 22 December 2024.

• See the Prota4U database.