Maranthes robusta (PROTA)

Plant Resources of Tropical Africa Introduction

List of species

General importance
Geographic coverage Africa
Geographic coverage World
Essential oil / exudate
Medicinal
Timber

Maranthes robusta (Oliv.) Prance

Protologue: Bull. Jard. Bot. Etat 46: 306 (1976).

Family: Chrysobalanaceae

Chromosome number: 2n = 20

Synonyms

Parinari robusta Oliv. (1871).

Vernacular names

Mahogany nut, Benin mahogany (En).

Origin and geographic distribution

Maranthes robusta occurs in West Africa, from Côte d’Ivoire eastward to Nigeria.

Uses

The wood of Maranthes robusta, named ‘koaramon’ in trade in Côte d’Ivoire, is mainly used for construction purposes for which it is processed green. It is difficult to use economically when re-sawing and machining of dried wood are required as even hardened steel cutting edges become blunt quickly. The wood may occasionally be used for joinery, mine props, vehicle bodies, railway sleepers, canoes and agricultural implements. It is also used as firewood and for charcoal production.

In Côte d’Ivoire bark decoctions and pounded leaves are applied as anodyne. Pregnant women take a decoction of the bark as a tonic.

Properties

The heartwood is red to dark red, resembling some kinds of mahogany. It darkens upon exposure and is distinctly demarcated from the pinkish or pale yellowish, thick sapwood. The grain is straight, irregular or interlocked, texture medium to coarse. The wood has little lustre. It has a scent of honey or bees wax when freshly cut, but the smell fades upon drying.

The wood is heavy, with a density of about 1000 kg/m³ at 12% moisture content, hard and exceptionally stiff. It air dries slowly and with serious degrade caused by splitting and twisting, and a combined air and kiln drying schedule is recommended to obtain good results. The rates of shrinkage are high, from green to oven dry 9% radial and 12% tangential. Once dry, the wood is very unstable in service. At 12% moisture content, the modulus of rupture is 183–242 N/mm², modulus of elasticity 21,500 N/mm², compression parallel to grain 89–93 N/mm², cleavage 30 N/mm and Chalais-Meudon side hardness 6.2.

The wood is very difficult to saw and work with both hand and machine tools; because of its high silica content it has a very rapid blunting effect on cutting edges, particularly when dry. While wood with high moisture content can be sawn and cut quite satisfactorily, stellite-tipped saw teeth and tungsten-carbide cutting tools are required for dry wood, but even these blunt quickly. The wood polishes fairly well when a filler is used, but picking up of interlocked grain may occur in planing. The wood is difficult to nail and pre-boring is needed. The gluing properties are satisfactory. The wood is moderately durable, being moderately resistant to termite attack and resistant to marine borer attack. Information on its response to fungi is not available. The heartwood is moderately resistant to preservative treatment, but sapwood is permeable.

The wood contains about 43% cellulose, 32% lignin, 16% pentosan, 3.5% ash and up to 2.6% silica. The solubility is 1.3% in alcohol-benzene, 1.0% in hot water and 17.1% in a 1% NaOH solution.

Adulterations and substitutes

The wood of Maranthes robusta closely resembles that of Parinari excelsa Sabine and Maranthes glabra (Oliv.) Prance and other Maranthes spp. It also resembles some grades of African mahogany (Khaya and Entandrophragma) and it has been described and classified as ‘false mahogany’.

Description

Small to medium-sized tree up to 20(–30) m tall; bole often low branching, cylindrical or irregular, up to 100 cm in diameter, sometimes with low buttresses; bark surface scaly with irregular patches, pale greyish to yellowish brown, inner bark granular, purplish or dark red, exuding some reddish gum; crown large, dense, reddish brown; twigs corky, often dark with raised rounded lenticels. Leaves arranged spirally, simple and entire; stipules small, early caducous; petiole stout, up to 1 cm long; blade elliptical, 6–12.5 cm × 2.5–6 cm, cuneate and with 2 glands at base, acuminate at apex, papery, densely yellowish brown short-hairy below, pinnately veined with 5–8 pairs of lateral veins. Inflorescence a terminal umbel-like panicle, strongly branched, short-hairy, many-flowered. Flowers bisexual, slightly zygomorphic, 5-merous; pedicel up to 4 mm long; receptacle obconical, curved, c. 3 mm long; sepals nearly orbicular, c. 4 mm long; petals nearly orbicular, up to 6 mm long, greenish white; stamens 18–25, free, c. 1 cm long; ovary superior, inserted laterally near apex of receptacle, 2-celled, style long and slender, curved. Fruit a fleshy, ellipsoid to obovoid drupe 3–3.5 cm × 2–2.5 cm, glabrous, greenish yellow turning reddish brown, few-seeded. Seedling with epigeal germination; hypocotyl 6–9 cm long, epicotyl 1.5–5 cm long, short-hairy; cotyledons thick and fleshy, 2.5–4 cm long, soon shrivelling; first 2 leaves opposite.

Other botanical information

Maranthes comprises 12 species, of which 10 occur in tropical Africa and one each in tropical Asia and tropical America.

Maranthes robusta has been confused with Maranthes glabra (Oliv.) Prance.

The wood of several other Maranthes species is similar to that of Maranthes robusta and Maranthes glabra and used for similar purposes.

Maranthes chrysophylla

Maranthes chrysophylla (Oliv.) Prance (synonym: Parinari chrysophylla Oliv.) is a medium-sized to fairly large tree up to 40 m tall, with straight bole up to 120 cm in diameter, occurring in evergreen rainforest from Sierra Leone to Gabon and south-western DR Congo. Its reddish wood is used in Liberia and Gabon for construction and planks; although heavy and strong, it is reported to be not durable upon exposure. The bark is poisonous.

Maranthes goetzeniana

Maranthes goetzeniana (Engl.) Prance (synonym: Parinari goetzeniana Engl.) is a medium-sized to fairly large tree up to 35(–50) m tall, with bole branchless for up to 20 m and up to 120 cm in diameter, occurring in evergreen forest from Tanzania to Zimbabwe and Mozambique. The pale brown wood is heavy, with a density of about 930 kg/m³ at 12% moisture content, moderately hard but not very strong. It is used for building poles, railway sleepers, tool handles and yokes, and also as firewood and for charcoal production. The fruit pulp is edible, and the fruit stones are broken and seeds eaten, especially by children during times of food scarcity. The bark produces a red dye. The flowers produce nectar which is collected by honey bees.

Maranthes polyandra

Maranthes polyandra (Benth.) Prance is a shrub or small tree up to 8 m tall, with short and gnarled bole, occurring from Mali eastward to Sudan in wooded savanna and grassland. Its wood is used for poles in construction and fences, and as firewood and for charcoal production. The wood has been used in tanning, and wood ash is used as a salt substitute. The leaves are chewed to stain the teeth. The fruits are edible. In traditional medicine, the roots are used against ulcers, syphilis and insanity. The bark is used to treat kwashiorkor and bark decoctions are taken against fever and general pain, and as a tonic by pregnant women; a bark decoction or powder is used in a bath to treat wounds and fractures. Leaves are applied to fractures and to treat abdominal pain in children.

Anatomy

Wood-anatomical description (IAWA hardwood codes):

• Growth rings: 2: growth ring boundaries indistinct or absent.
• Vessels: 5: wood diffuse-porous; 9: vessels exclusively solitary (90% or more); 13: simple perforation plates; 22: intervessel pits alternate; 25: intervessel pits small (4–7 μm); (31: vessel-ray pits with much reduced borders to apparently simple: pits rounded or angular); 32: vessel-ray pits with much reduced borders to apparently simple: pits horizontal (scalariform, gash-like) to vertical (palisade); 43: mean tangential diameter of vessel lumina ≥ 200 μm; 46: ≤ 5 vessels per square millimetre.
• Tracheids and fibres: (60: vascular/vasicentric tracheids present); 62: fibres with distinctly bordered pits; 63: fibre pits common in both radial and tangential walls; 66: non-septate fibres present; 70: fibres very thick-walled.
• Axial parenchyma: (85: axial parenchyma bands more than three cells wide); 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; (104: all ray cells procumbent); 106: body ray cells procumbent with one row of upright and/or square marginal cells; 116: ≥ 12 rays per mm.
• Mineral inclusions: 159: silica bodies present; 160: silica bodies in ray cells.

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

Growth and development

The tree architecture of Maranthes robusta is according to the growth model of Troll, in which the axes all have a tendency to grow at an oblique angle or horizontally with continual superposition. The main-line axes contribute partly to the trunk and partly to the branches. Growth in height is effected by the ability of the basal part of each shoot to assume an erect position by secondary growth.

Maranthes robusta regenerates well in shade. In Ghana flowering is usually not seasonal and occurs in January–July and September–January; ripe fruits are normally found in January–April. The seeds are possibly dispersed by elephants. They are eaten by primates.

Ecology

The characteristic habitat of Maranthes robusta is swamp forest, often near the coast. It also occurs in drier types of semi-evergreen rainforest, often in association with Brachystegia eurycoma Harms, Irvingia gabonensis (Aubry-Lecomte ex O’Rorke) Baill. and Triplochiton scleroxylon K.Schum.

Diseases and pests

Standing trees of Maranthes robusta are susceptible to attacks by large borers.

Genetic resources

Maranthes robusta is widespread and although current data on its abundance are lacking and its habitat is shrinking rapidly, there are no indications that it is seriously threatened by genetic erosion.

Prospects

The unusual abrasiveness, stiffness, high density and shrinkage values of the wood of Maranthes robusta limit its usage to domestic markets, where it will continue to be useful for purposes for which it can be processed green. Its high price as firewood indicates that demand for this purpose is strong.

Major references

• 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., 1985. The useful plants of West Tropical Africa. 2nd Edition. Volume 1, Families A–D. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 960 pp.

• de Koning, J., 1983. La forêt de Banco. Part 2: La Flore. Mededelingen Landbouwhogeschool Wageningen 83–1. Wageningen, Netherlands. 921 pp.

• Irvine, F.R., 1961. Woody plants of Ghana, with special reference to their uses. Oxford University Press, London, United Kingdom. 868 pp.

• Keay, R.W.J., 1989. Trees of Nigeria. A revised version of Nigerian trees (1960, 1964) by Keay, R.W.J., Onochie, C.F.A. & Stanfield, D.P. Clarendon Press, Oxford, United Kingdom. 476 pp.

• 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.

• Prance, G.T. & Sothers, C.A., 2003. Chrysobalanaceae 2: Acioa to Magnistipula. Species Plantarum: Flora of the World. Part 10. Australian Biological Resources Study, Canberra, Australia. 268 pp.

• Prance, G.T. & White, F., 1988. The genera of Chrysobalanaceae: A study in practical and theoretical taxonomy and its relevance to evolutionary biology. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences 320(1197): 1–184.

• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan. 248 pp.

• White, F., 1976. The taxonomy, ecology and chorology of African Chrysobalanaceae (excluding Acioa). Bulletin du Jardin botanique national de Belgique 46(3–4): 265–350.

Other references

• Arbonnier, M., 2004. Trees, shrubs and lianas of West African dry zones. CIRAD, Margraf Publishers Gmbh, MNHN, Paris, France. 573 pp.

• Aubréville, A., 1959. La flore forestière de la Côte d’Ivoire. Deuxième édition révisée. Tome premier. Publication No 15. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 369 pp.

• Bryce, J.M., 1967. The commercial timbers of Tanzania. Tanzania Forest Division, Utilisation Section, Moshi, Tanzania. 139 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.

• Hall, J.B. & Swaine, M.D., 1981. Distribution and ecology of vascular plants in a tropical rain forest: forest vegetation of Ghana. W. Junk Publishers, the Hague, Netherlands. 383 pp.

• Hawthorne, W., 1990. Field guide to the forest trees of Ghana. Natural Resources Institute, for the Overseas Development Administration, London, United Kingdom. 275 pp.

• Hawthorne, W.D., 1995. Ecological profiles of Ghanaian forest trees. Tropical Forestry Papers 29. Oxford Forestry Institute, Department of Plant Sciences, University of Oxford, United Kingdom. 345 pp.

• 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.

• Lovett, J.C., Ruffo, C.K., Gereau, R.E. & Taplin, J.R.D., 2007. Field guide to the moist forest trees of Tanzania. [Internet] Centre for Ecology Law and Policy, Environment Department, University of York, York, United Kingdom. http://celp.org.uk/ projects/ tzforeco/. November 2011.

• Melville, R., 1936. A list of true and false mahoganies. Bulletin of Miscellaneous Information Kew 1936(3): 193–210.

• Poorter, L., Bongers, F., Kouamé, F.Y.N. & Hawthorne, W.D., 2004. Biodiversity of West African forests: an ecological atlas of woody plant species. CABI, Wallingford, United Kingdom. 521 pp.

• 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.

• Sallenave, P., 1955. Propriétés physiques et mécaniques des bois tropicaux de l’Union française. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 129 pp.

• Savard, J., Besson, A. & Morize, S., 1954. Analyse chimique des bois tropicaux. Publication No 5, Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 191 pp.

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

• Taylor, C.J., 1960. Synecology and silviculture in Ghana. Thomas Nelson and Sons, Edinburgh, United Kingdom. 418 pp.

• White, F., 1978. Chrysobalanaceae. In: Launert, E. (Editor). Flora Zambesiaca. Volume 4. Flora Zambesiaca Managing Committee, London, United Kingdom. pp. 33–48.

Sources of illustration

• Aubréville, A., 1959. La flore forestière de la Côte d’Ivoire. Deuxième édition révisée. Tome premier. Publication No 15. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 369 pp.

Author(s)

• J.R. Cobbinah, Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

• E.A. Obeng, Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Correct citation of this article

Cobbinah, J.R. & Obeng, E.A., 2012. Maranthes robusta (Oliv.) Prance. 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 31 March 2025.

• See the Prota4U database.