Petersianthus macrocarpus

Family

Lecythidaceae

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Chromosome number

2n = 52

Synonyms

Combretodendron africanum (Welw. ex Benth.) Exell (1930), Combretodendron macrocarpum (P.Beauv.) Keay (1958).

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Vernacular names

Stinkwood tree, soap tree (En).

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Origin and geographic distribution

Petersianthus macrocarpus is distributed from Guinea eastward to the Central African Republic and southward to DR Congo and northern Angola.

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Uses

The wood of Petersianthus macrocarpus is used for construction, carpentry, furniture, canoes, mortars, tool handles, sliced veneer and plywood. It is suitable for flooring, mine props, vehicle bodies, railway sleepers, sporting goods, toys, novelties, agricultural implements and draining boards. It is valued as firewood and for charcoal production.
In Côte d’Ivoire the bark is used as a purgative and laxative and is considered abortifacient. In Ghana bark decoctions are taken as expectorant, and in DR Congo as cholagogue and as a cure for stomach pain, pneumonia and jaundice. In Equatorial Guinea the bark is administered as anthelminthic and to cure cough. Bark decoctions are widely used to clean wounds and to promote wound healing. Hot bark is applied to the skin against muscle soreness. In Gabon leaf decoctions have been used orally and by enema for the treatment of haemorrhoids, constipation, paralysis and ulcerative wounds. In Cameroon the leaves are used as a medicine for dysentery. Edible caterpillars, which feed on the leaves, are collected and eaten after roasting or boiling.

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Production and international trade

Wood of Petersianthus macrocarpus, known as ‘essia’, ‘esia’, ‘abalé’, ‘abing’ and ‘owewe’, is mainly used locally. Ghana has been exporting considerable volumes, predominantly as sliced veneer, but in 1998 still about 2350 m³ of logs were exported.

Properties

The heartwood is reddish brown, darkening upon exposure and often speckled with darker streaks, and is distinctly demarcated from the 4–10 cm thick, yellowish white sapwood. The grain is straight to interlocked, texture moderately coarse to fine. Quarter-sawn wood shows a nice ray figure. The green wood produces an extremely unpleasant smell when cut, but this disappears upon drying.
The wood is medium-weight to heavy, with a density of 630–920 kg/m³ at 12% moisture content, and moderately hard. Drying needs to be done slowly to avoid splitting, checking, warping or even collapse. The rates of shrinkage are high, from green to oven dry 4.3–6.8% radial and 9.1–11.6% tangential. It is recommended to quarter-saw logs before drying. Once dry, the wood is moderately stable to unstable in service.
At 12% moisture content, the modulus of rupture is (76–)112–187 N/mm², modulus of elasticity 7940–19,300 N/mm², compression parallel to grain 43–75 N/mm², shear 8.5–14.5 N/mm², cleavage 13–37 N/mm, Janka side hardness 6360–9690 N, Janka end hardness 7070–10,400 N and Chalais-Meudon side hardness 2.9–6.0.
The wood usually saws well, but sometimes with some difficulty because of high density and the presence of interlocked grain resulting in a tendency of over-heating saw blades, thereby charring sawn surfaces. A reduced cutting angle of 20° or less is recommended in planing to avoid picking up of grain at surfaces. The wood has a tendency to char in boring and chiselling operations. It may split upon nailing and screwing, and pre-boring is advised. It stains and polishes well when a filler is used. The bending properties are poor. The heartwood is moderately to fairly durable, with contradictory reports on resistance to termites and borers; it is quite resistant to fungal attacks. The sapwood is fairly resistant to Lyctus attack, but susceptible to blue stain. The heartwood is resistant to impregnation by preservatives, but the sapwood is permeable.
The wood contains 39.5–40.5% cellulose, 29–30% lignin, 14.5–15.5% pentosan, 0.4–0.6% ash and little silica. The solubility is 6.2–9.6% in alcohol-benzene, 2.1–3.3% in hot water and 18.3% in a 1% NaOH solution.
The bark contains high levels of sterols, tannins and saponosides, and traces of flavonoids. Bark extracts have shown strong filaricidal effect against Loa loa. High concentrations of bark extract act on smooth muscles, circulation, heart-muscles and interferes with the oestrus cycle, conception and pregnancy. An ethanolic leaf extract showed antiproliferative activity on human colon cancer cells (IC₅₀ = 17 μg/ml).

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Adulterations and substitutes

In Ghana Petersianthus macrocarpus wood has been suggested as a good substitute for the woods of Uapaca guineensis Müll.Arg., Tieghemella heckelii (A.Chev.) Roberty and Diospyros kamerunensis Gürke which have become scarce as a result of exploitation.

Description

Deciduous medium-sized to large tree up to 45 m tall; bole branchless for up to 25 m, usually straight and cylindrical, up to 130 cm in diameter, thickened and slightly fluted at base or with small buttresses; bark surface longitudinally fissured and becoming scaly, medium to dark brown, inner bark fibrous, cream-coloured to yellow-orange or pink-brown, with an unpleasant smell; crown rounded, fairly dense; twigs finely hairy, becoming glabrous. Leaves arranged spirally, crowded towards the ends of twigs, simple; stipules absent; petiole 0.5–2.5 cm long, narrowly winged; blade elliptical or obovate, 6–16 cm × 4–7 cm, base cuneate, apex acute to acuminate, margin entire to slightly wavy or slightly toothed, papery, nearly glabrous, pinnately veined with 6–12 pairs of lateral veins. Inflorescence a terminal panicle or raceme up to 10 cm long, short-hairy. Flowers bisexual, regular, 4-merous; pedicel 1.5–2 mm long, jointed below the middle; sepals broadly ovate, c. 2 mm × 2 mm, attached to winged receptacle; petals broadly elliptical, c. 7 mm × 7 mm, white to pale green, soon caducous; stamens numerous, fused at base, c. 1 cm long, early caducous; ovary inferior, 2-celled, style straight, c. 1 cm long. Fruit a spindle-shaped nut, with 4 papery wings up to 7 cm × 3.5 cm, indehiscent, 1-seeded. Seeds spindle-shaped, 1–1.5 cm long. Seedling with epigeal germination; hypocotyl c. 5 cm long, epicotyl very short; cotyledons leafy, elliptical to ovate, 1–1.5 cm long, erect; leaves arranged spirally, nearly sessile, margins finely toothed.

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Other botanical information

Petersianthus comprises only 2 species, one in Africa and the other endemic to the Philippines.

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; 27: intervessel pits large (≥ 10 μm); 30: vessel-ray pits with distinct borders; similar to intervessel pits in size and shape throughout the ray cell; 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); 33: vessel-ray pits of two distinct sizes or types in the same ray cell; 42: mean tangential diameter of vessel lumina 100–200 μm; 47: 5–20 vessels per square millimetre; 56: tyloses common. 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); 79: axial parenchyma vasicentric; 80: axial parenchyma aliform; 82: axial parenchyma winged-aliform; 83: axial parenchyma confluent; 92: four (3–4) cells per parenchyma strand; 93: eight (5–8) cells per parenchyma strand; 94: over eight cells per parenchyma strand. Rays: (97: ray width 1–3 cells); 98: larger rays commonly 4- to 10-seriate; (102: ray height > 1 mm); 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; 110: sheath cells present; 113: disjunctive ray parenchyma cell walls present; 115: 4–12 rays per mm. Mineral inclusions: 136: prismatic crystals present; (137: prismatic crystals in upright and/or square ray cells); 138: prismatic crystals in procumbent ray cells.
(L. Awoyemi, A.A. Oteng-Amoako & P. Baas)

Growth and development

Growth of seedlings is slow; after 9 months they reach about 11 cm tall. When planted in full sun, seedlings were only 75 cm tall after 5 years, but in moderate shade they reached about 1 m tall 4 years after planting.
Although Petersianthus macrocarpus is considered to be an indicator of disturbances in the forest, seedlings have been reported to tolerate some shade and are most common in small forest gaps; saplings can be found in small as well as larger gaps.
Trees are leafless for a short period towards the end of the dry season. Leaves turn red before shedding. In Liberia and Côte d’Ivoire flowering is irregular but peaks around December and May. During flowering the ground under the tree is covered with fallen petals and stamens with a penetrant and unpleasant smell. It has been reported that abundant fruiting occurs twice a year. The fruits are dispersed by wind. In forests where elephants are present, Petersianthus macrocarpus trees have strongly swollen bases as a reaction to regular debarking. After debarking the bark grows back not only from the edge of the injury but also from pores in the wood which speeds up recovery and results in reduced rates of infection.

Ecology

In Liberia Petersianthus macrocarpus is most common in moist semi-deciduous forest and more uncommon in evergreen forest, but in Côte d’Ivoire and Ghana it seems to be more abundant in evergreen forest and transitional zones between evergreen and moist semi-deciduous forest. It apparently does not tolerate waterlogging for longer periods. In Central Africa it is reported to be characteristic for secondary forest. In southern Cameroon it is frequently found in agroforestry plantations of cocoa. Petersianthus macrocarpus prefers regions with an annual rainfall of about 2000 mm.

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Propagation and planting

In Guinea and Côte d’Ivoire seeds are best collected in January–February(–April) and August. There are about 4300 seeds per kg. The germination rate is only 15–25%, and many fruits do not develop a viable seed or are attacked by insects. Germination starts 3.5–7(–10) weeks after sowing. Seedlings are ready for planting after 1 year. In planting tests in Guinea, mortality was quite high, particularly when seedlings had been planted in full sun.

Management

In forest in southern Cameroon, the average density of Petersianthus macrocarpus trees with a bole diameter of more than 60 cm is 0.3–0.4 trees per ha, with a mean wood volume of 1.5–3 m³ per ha. In Gabon the mean wood volume has been reported as 0.2 m³/ha. Trees can be coppiced.

Harvesting

In Ghana, Central African Republic and Gabon, the minimum bole diameter allowed for felling is 70 cm. In 2001 it was 50 cm in Cameroon.

Yield

A bole felled in south-western DR Congo branchless for 20.5 m and with a diameter of 85 cm yielded 7.7 m³ of wood.

Handling after harvest

It has been recorded that freshly felled logs were subject to pinhole borer attack, but in general logs do not deteriorate rapidly when left in the forest after felling, although deep splits may develop after a longer time. Freshly felled logs are too heavy to be transported by river.

Genetic resources and breeding

Petersianthus macrocarpus is fairly widespread in West and Central Africa and occurs commonly in secondary forest. Export volumes are low, certainly so from Ghana. It is rarely harvested for the international timber market and not commonly cut for local use because of the unpleasant smell and the hardness of the wood. Hence, at present the species is not threatened.

Prospects

Petersianthus macrocarpus wood has been suggested as a substitute of other more durable woods which have been over-exploited. However, little information is available on growth rates, propagation and silvicultural aspects, but the data available suggest that low rates of regeneration may hamper sustainable exploitation from natural forest. More research is justified in the light of its fair wood quality, good bole shape and size and its preference for disturbed forest.

Major references

• CIRAD Forestry Department, 2009. Essia. [Internet] Tropix 6.0. http://tropix.cirad.fr/ africa/ essia.pdf. Accessed January 2012.
• de Koning, J., 1983. La forêt de Banco. Part 2: La Flore. Mededelingen Landbouwhogeschool Wageningen 83–1. Wageningen, Netherlands. 921 pp.
• Fouarge, J. & Gérard, G., 1964. Bois du Mayumbe. Institut National pour l’Etude Agronomique du Congo (INEAC), Brussels, Belgium. 579 pp.
• Irvine, F.R., 1961. Woody plants of Ghana, with special reference to their uses. Oxford University Press, London, United Kingdom. 868 pp.
• Liben, L., 1971. Lecythidaceae. In: Bamps, P. (Editor). Flore du Congo, du Ruanda et du Burundi. Spermatophytes. Jardin botanique national de Belgique, Brussels, Belgium. 9 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.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan. 248 pp.
• Voorhoeve, A.G., 1965. Liberian high forest trees. A systematic botanical study of the 75 most important or frequent high forest trees, with reference to numerous related species. Pudoc, Wageningen, Netherlands. 416 pp.
• White, L. & Abernethy, K., 1997. A guide to the vegetation of the Lopé Reserve, Gabon. 2nd edition. Wildlife Conservation Society, New York, United States. 224 pp.

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Other references

• Addae-Mensah, A.D. & Ayarkwa, J., 1998. Some machining qualities of selected lesser-used timber species in Ghana. Ghana Journal of Forestry 6: 8–14.
• Aubréville, A., 1959. La flore forestière de la Côte d’Ivoire. Deuxième édition révisée. Tome troisième. Publication No 15. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 334 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.
• Fouarge, J., Quoilin, J. & Roosen, P., 1970. Essais physiques, mécaniques et de durabilité de bois de la République Démocratique du Congo. Série technique No 76. Institut National pour l’Etude Agronomique du Congo (INEAC), Brussels, Belgium. 40 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.
• Keay, R.W.J., 1954. Lecythidaceae. In: Keay, R.W.J. (Editor). Flora of West Tropical Africa. Volume 1, part 1. 2nd Edition. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. pp. 241–245.
• Kouitcheu-Mabeku, L.B., Kuiate, J.R. & Essame, J.L.O., 2011. Screening of some plants used in the Cameroonian folk medicine for the treatment of infectious diseases. International Journal of Biology 3(4): 13–21.
• Mangenot, S. & Mangenot, G., 1962. Enquête sur les nombres chromosomiques dans une collection d’espèces tropicales. Revue de Cytologie et Biologie Végétale 25: 411–447.
• Mengome, L.-E., Feuya Tchoua, G.R., Eba, F. & Emvo, E.N., 2009. Antiproliferative effect of alcoholic extracts of some Gabonese medicinal plants on human colonic cancer cells. African Journal of Traditional, Complementary and Alternative Medicines 6(2): 112–117.
• Mengome, L.-E., Akue, J.P., Souza, A., Feuya Tchoua, G.R. & Emvo, E.N., 2010. In vitro activities of plant extracts on human Loa loa isolates and cytotoxicity for eukaryotic cells. Parasitology Research 17(3): 643–650.
• Nkeoua, G. & Boundzanga, G.C., 1999. Données sur les produits forestiers non ligneux en République du Congo. FAO, Brazzaville, Congo. 125 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.
• 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.
• Sallenave, P., 1955. Propriétés physiques et mécaniques des bois tropicaux de l’Union française. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 129 pp.
• Sallenave, P., 1964. Propriétés physiques et mécaniques des bois tropicaux. Premier supplément. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 79 pp.
• Sallenave, P., 1971. Propriétés physiques et mécaniques des bois tropicaux. Deuxième supplément. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 128 pp.
• Senterre, B. & Lejoly, J., 2001. Trees diversity in the Nsork rain forest (Río Muni, Equatorial Guinea). Acta Botanica Gallica 148(3): 227–235.
• Terashima, H. & Ichikawa, M., 2003. A comparative ethnobotany of the Mbuti and Efe hunter-gatherers in the Ituri forest, Democratic Republic of Congo. African Study Monographs 24(1–2): 1–168.
• Wilks, C. & Issembé, Y., 2000. Les arbres de la Guinée Equatoriale: Guide pratique d’identification: région continentale. Projet CUREF, Bata, Guinée Equatoriale. 546 pp.

Afriref references

Sources of illustration

• Liben, L., 1971. Lecythidaceae. In: Bamps, P. (Editor). Flore du Congo, du Ruanda et du Burundi. Spermatophytes. Jardin botanique national de Belgique, Brussels, Belgium. 9 pp.
• Voorhoeve, A.G., 1965. Liberian high forest trees. A systematic botanical study of the 75 most important or frequent high forest trees, with reference to numerous related species. Pudoc, 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.

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Author(s)

•	F.W. Owusu Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Editors

•	R.H.M.J. Lemmens PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
•	D. Louppe CIRAD, Département Environnements et Sociétés, Cirad es-dir, Campus international de Baillarguet, TA C 105 / D (Bât. C, Bur. 113), 34398 Montpellier Cédex 5, France
•	A.A. Oteng-Amoako Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Associate editors

•	E.A. Obeng 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

Owusu, F.W., 2012. Petersianthus macrocarpus (P.Beauv.) Liben. [Internet] Record from PROTA4U. 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. <http://www.prota4u.org/search.asp>. Accessed .

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