Prioria balsamifera (PROTA)
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Introduction |
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| Geographic coverage Africa | Error creating thumbnail: Error creating thumbnail:
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| Geographic coverage World | Error creating thumbnail:
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| Essential oil / exudate | Error creating thumbnail:
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| Timber | Error creating thumbnail: Error creating thumbnail:
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| Conservation status | Error creating thumbnail: Error creating thumbnail: Error creating thumbnail: Error creating thumbnail:
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Prioria balsamifera (Vermoesen) Breteler
- Protologue: Wageningen Agric. Univ. Pap. 99–3: 21 (1999).
- Family: Caesalpiniaceae (Leguminosae - Caesalpinioideae)
Synonyms
- Gossweilerodendron balsamiferum (Vermoesen) Harms (1925).
Vernacular names
- Agba (En).
- Tola (Fr).
- Tola branca (Po).
Origin and geographic distribution
Prioria balsamifera is distributed from southern Nigeria eastward to DR Congo and south to Cabinda (Angola).
Uses
The wood, known in trade as ‘tola’ or ‘agba’, is used for construction, flooring, joinery, interior trim, ship building, furniture, boxes, crates, shingles, veneer and plywood. It is suitable for vehicle bodies, toys, novelties, vats, carvings, turnery, hardboard, particle board and pulpwood. The boles are traditionally used to make canoes. The resin exuding from the sapwood has been used as an illuminant, although it reportedly causes a smoky flame, and for caulking canoes.
Production and international trade
In 1961–1970 Nigeria exported on average 22,000 m³ of logs and 11,000 m³ of sawn wood of Prioria balsamifera per year. The export of logs from Gabon increased from 20,500 m³ in 1991 to 56,000 m³ in 2001. In 1999 Prioria balsamifera ranked 7th on the list of most important Gabonese export timbers. Exports decreased to 13,800 m³ in 2005. In 2004 Congo exported 13,000 m³ of logs at an average price of US$ 141/m³, and 1000 m³ of veneer at an average price of US$ 309/m³. Cameroon exported 5600 m³ of logs in 1999, 12,300 m³ in 2000, 3000 m³ in 2001 and only 850 m³ in 2003. In 2006 small amounts of plywood were exported from Cameroon at an average price of US$ 867/m³.
Properties
The heartwood is pale yellowish brown, darkening to pale reddish brown upon exposure, and not distinctly demarcated from the up to 10 cm wide, slightly paler sapwood. There is an intermediate zone of 2–3 cm wide between sapwood and heartwood. The grain is straight or slightly interlocked, texture moderately fine and even. Wood surfaces are lustrous. Freshly cut wood has a resinous or slightly peppery odour. The intermediate zone between sapwood and heartwood exudes a greenish resin in freshly cut logs, and resin pockets may also be present near the heart of the bole.
The wood is lightweight to medium-weight, with a density of 445–580 kg/m³ at 12% moisture content, and moderately hard. It air dries rapidly, with only slight tendency to distortion and checking. Kiln drying should be done with care to avoid collapse; it is recommended to use moderate temperatures to avoid excessive resin exudation. The rates of shrinkage are moderate, from green to oven dry 2.4–3.0% radial and 5.5–6.2% tangential. Once dry, the wood is stable in service. At 12% moisture content, the modulus of rupture is 70–94 N/mm², modulus of elasticity 6075–10,900 N/mm², compression parallel to grain 33–43 N/mm², shear 6.5–11.5 N/mm², cleavage 9–14 N/mm, Janka side hardness 2440–3300 N, Janka end hardness 3510–4400 N and Chalais-Meudon side hardness 1.2–2.3.
The wood is easy to saw and work with both hand and machine tools, with little blunting effect on saw teeth and cutting edges. However, tools may be clogged by resin and boards may stick together. After drying of the wood, the difficulties due to the presence of resin have disappeared. The nailing and screwing properties are satisfactory, and the wood glues, paints and varnishes well although the presence of resin may cause difficulties and some staining may occur. It polishes to an excellent finish. The steam bending properties are moderately good. The logs are suitable for rotary peeling, giving a good-quality veneer that can be glued satisfactorily to produce plywood. The wood is moderately durable, being moderately resistant to fungi, but rather susceptible to termite, dry-wood borer and marine borer attacks. The heartwood is moderately resistant to impregnation with preservatives, the sapwood is permeable. Saw dust can cause irritation of eyes and mucous membranes in wood workers.
Tests on the pulping properties for paper production showed moderate results; the paper was of medium-quality. The wood contains 39–40% cellulose, 27–30% lignin, 16.5–19.5% pentosan, 0.3–0.4% ash and little silica. The solubility is 10.1–11.3% in alcohol-benzene, 1.0–1.7% in hot water, and 17.9–20.2% in a 1% NaOH solution.
Adulterations and substitutes
The wood of Prioria balsamifera resembles that of African mahogany (Entandrophragma and Khaya spp.) and has been traded as a substitute.
Description
- Evergreen, large to very large tree up to 55(–60) m tall; bole branchless for up to 25(–30) m, straight and cylindrical, up to 150(–300) cm in diameter, without buttresses; bark surface scaly with elongate scales, sometimes slightly fissured, greyish brown to reddish brown, inner bark fibrous, reddish; crown usually comparatively small, with sinuous branches; twigs glabrous.
- Leaves alternate, imparipinnately or paripinnately compound with (4–)6–8(–9) leaflets; stipules small, very early caducous; petiole 1–2(–3) cm long, rachis 4.5–7(–8) cm long, grooved; petiolules twisted, 1–3(–4) mm long; leaflets alternate, obliquely ovate-elliptical to obovate-elliptical, (2.5–)5–7(–9) cm × (1.5–)2–3(–4) cm, rounded to obtuse at base, obtuse to rounded, sometimes slightly acuminate at apex, thin-leathery, glabrous, pinnately veined with 9–13 pairs of lateral veins.
- Inflorescence an axillary compound raceme up to 12 cm long, with branches up to 7 cm long, short-hairy.
- Flowers bisexual, regular, whitish; pedicel up to 0.5 mm long; sepals 4(–5), elliptical, 1–2 mm long, spreading, hairy at margins; petals absent; stamens usually 10, free, 3–4 mm long, filaments hairy; ovary superior, with a c. 1 mm long stipe, hairy, 1-celled, style slender, curved.
- Fruit an ovoid, flattened, indehiscent, 1-seeded pod with large wing at base, (7–)12–15 cm × (2–)3–4.5 cm, with numerous resin pockets, wing reticulately veined.
- Seed rounded to ellipsoid, 2–3 cm long, shallowly grooved.
- Seedling with hypogeal germination; epicotyl 8–22 cm long, with some small scales; first leaves alternate, with 4–6 leaflets.
Other botanical information
Prioria comprises 14 species, 7 in Africa (most of them in Central Africa), 6 in tropical Asia and on islands of the Pacific Ocean, and 1 in Central America. Until 1999 the name Prioria was reserved for the American species, but then the genera Kingiodendron from Asia and the Pacific region, and Gossweilerodendron and Oxystigma from tropical Africa have been added based on morphological evidence. Wood-anatomical, pollen and molecular studies support the close relationship, but more studies are needed to assess generic delimitation.
Prioria joveri
Prioria joveri (Normand ex Aubrév.) Breteler (synonym: Gossweilerodendron joveri Normand ex Aubrév.) is a large tree up to 40 m tall, with bole up to 150 cm in diameter. It is found in rainforest in Cameroon, Equatorial Guinea and northern Gabon, and differs from Prioria balsamifera in more numerous lateral veins in its leaflets and in its fruit tapering to a narrow, curved top. In trade, logs of this species are undoubtedly mixed with those of Prioria balsamifera and its wood can probably be used for similar purposes. Prioria joveri is classified as vulnerable in the IUCN Red List.
Anatomy
Wood-anatomical description (IAWA hardwood codes):
- Growth rings: 1: growth ring boundaries distinct.
- Vessels: 5: wood diffuse-porous; 13: simple perforation plates; 22: intervessel pits alternate; 23: shape of alternate pits polygonal; 24: intervessel pits minute (≤ 4 μm); 25: intervessel pits small (4–7 μm); 29: vestured pits; 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; 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; 66: non-septate fibres present; 69: fibres thin- to thick-walled.
- Axial parenchyma: (76: axial parenchyma diffuse); 79: axial parenchyma vasicentric; (80: axial parenchyma aliform); 83: axial parenchyma confluent; 85: axial parenchyma bands more than three cells wide; 89: axial parenchyma in marginal or in seemingly marginal bands; 90: fusiform parenchyma cells; 91: two cells per parenchyma strand; (92: four (3–4) cells per parenchyma strand).
- Rays: 97: ray width 1–3 cells; 98: larger rays commonly 4- to 10-seriate; 104: all ray cells procumbent; 106: body ray cells procumbent with one row of upright and/or square marginal cells; 115: 4–12 rays per mm.
- Secretory elements and cambial variants: 129: axial canals diffuse.
- Mineral inclusions: (136: prismatic crystals present); (142: prismatic crystals in chambered axial parenchyma cells).
Growth and development
Prioria balsamifera is shade tolerant. Natural regeneration can be abundant. In semi-deciduous forest in south-western DR Congo, up to 7800 seedlings and saplings have been counted per ha. Seed germination can be gregarious under a closed canopy, but it seems that for good growth of seedlings openings in the canopy are needed. In Nigeria and Cameroon, flowering trees are mainly found from January to March and fruits ripen a few months later. In DR Congo flowering and fruiting trees have been recorded throughout the year. Fruits are dispersed by wind, sometimes quite far from the parent tree.
Ecology
Prioria balsamifera is most common in lowland semi-deciduous forest up to 600 m altitude, but can also be found in evergreen forest. It prefers deep ferruginous soils and can also be found on sandy soils.
Management
Prioria balsamifera usually occurs quite scattered in the forest, although often in small groups of a few trees. In Cameroon the average number of trees with a bole diameter of more than 60 cm is 0.05–0.1 per ha, with a mean wood volume of 0.3–1.25 m³/ha, but locally up to 6 m³/ha. Locally in eastern Gabon and Congo, 4–6 exploitable trees per ha have been recorded.
Harvesting
Some caution is needed during harvesting operations because boles may have brittle heart and ring or wind shakes. The minimum bole diameter allowed for harvesting is 80 cm in Gabon and DR Congo, and 100 cm in Cameroon.
Yield
A bole of 13 m long and 120 cm in diameter yielded 8.7 m³ of wood.
Handling after harvest
Freshly harvested logs are sometimes attacked by pinhole borers, but chemical protection of logs is usually not needed when the logs do not stay in the forest for longer periods. They float in water and thus can be transported by river.
Genetic resources
Prioria balsamifera suffered from habitat loss and heavy exploitation and has therefore been included as endangered in the IUCN Red List of threatened species. FAO recommends that the genetic material of this species should be protected for a future planting programme.
Prospects
Prioria balsamifera produces an important commercial timber for the international market, but unfortunately there has been no attention for proper management practices to ensure sustainable production. It deserves research attention on genetics and silviculture for future planting programmes.
Major references
- ATIBT (Association Technique Internationale des Bois Tropicaux), 1986. Tropical timber atlas: Part 1 – Africa. ATIBT, Paris, France. 208 pp.
- Aubréville, A., 1970. Légumineuses - Césalpinioidées (Leguminosae - Caesalpinioideae). Flore du Cameroun. Volume 9. Muséum National d’Histoire Naturelle, Paris, France. 339 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.
- Breteler, F.J., 1999. A revision of Prioria, including Gossweilerodendron, Kingiodendron, Oxystigma, and Pterygopodium (Leguminosae - Caesalpinioideae - Detarieae) with emphasis on Africa. Wageningen Agricultural University Papers 99–3. 61 pp.
- Burkill, H.M., 1995. The useful plants of West Tropical Africa. 2nd Edition. Volume 3, Families J–L. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 857 pp.
- CTFT (Centre Technique Forestier Tropical), 1979. Tola. Bois et Forêts des Tropiques 185: 25–36.
- de Saint-Aubin, G., 1963. La forêt du Gabon. Publication No 21 du Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 208 pp.
- Fouarge, J. & Gérard, G., 1964. Bois du Mayumbe. Institut National pour l’Etude Agronomique du Congo (INEAC), Brussels, Belgium. 579 pp.
- Tailfer, Y., 1989. La forêt dense d’Afrique centrale. Identification pratique des principaux arbres. Tome 2. CTA, Wageningen, Pays Bas. pp. 465–1271.
- Wilczek, R., Léonard, J., Hauman, L., Hoyle, A.C., Steyaert, R., Gilbert, G. & Boutique, R., 1952. Caesalpiniaceae. In: Robyns, W., Staner, P., Demaret, F., Germain, R., Gilbert, G., Hauman, L., Homès, M., Jurion, F., Lebrun, J., Vanden Abeele, M. & Boutique, R. (Editors). Flore du Congo belge et du Ruanda-Urundi. Spermatophytes. Volume 3. Institut National pour l’Étude Agronomique du Congo belge, Brussels, Belgium. pp. 234–554.
Other references
- African Regional Workshop (Conservation & Sustainable Management of Trees, Zimbabwe), 1998. Gossweilerodendron balsamiferum. In: IUCN. 2010 IUCN Red list of threatened species. Version 2010.4. [Internet] http://www.iucnredlist.org. November 2010.
- Antoine, R.C., Berben, J.C. & Sauvage, G., 1959. Etude du sciage de Gossweilerodendron balsamiferum (Tola). Le debit des bois à la scie à ruban no 4. INEAC, Série technique no 57. Bruxelles, Belgique. 41 pp.
- Christy, P., Jaffré, R., Ntougou, O. & Wilks, C., 2003. La forêt et la filière bois au Gabon. Projet Aménagement Forestier et Environnement, Libreville, Gabon. 389 pp.
- Chudnoff, M., 1980. Tropical timbers of the world. USDA Forest Service, Agricultural Handbook No 607, Washington D.C., United States. 826 pp.
- CIRAD Forestry Department, 2008. Tola. [Internet] Tropix 6.0. http://tropix.cirad.fr/ africa/ tola.pdf. November 2010.
- Cordiez, F., 2000. Etude des mécanismes de régénération naturelle de l’agba (Gossweilerodendron balsamiferum Harms), l’azobé (Lophira alata Banks ex Gaertn.f.), le movingui (Distemonanthus benthamianus Baill.) et l’ozigo (Dacryodes buettneri (Engl.) H.J. Lam) au Gabon. FUSAGx, Gembloux, Belgium. 88 pp.
- Fouarge, J., Quoilin, J. & Roosen, P., 1970. Essais physiques, mécaniques et de durabilité de bois de la République Democratique du Congo. Série technique No 76. Institut National pour l’Etude Agronomique du Congo (INEAC), Brussels, Belgium. 40 pp.
- Fouarge, J., Sacré, E. & Mottet, A., 1950. Appropriation des bois congolais aux besoins de la métropole. Série Technique No 38. Institut National pour l’Étude Agronomique du Congo belge (INEAC), Brussels, Belgium. 17 pp.
- Gérard, J., Edi Kouassi, A., Daigremont, C., Détienne, P., Fouquet, D. & Vernay, M., 1998. Synthèse sur les caractéristiques technologiques des principaux bois commerciaux africains. Document Forafri 11. Cirad, Montpellier, France. 185 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.
- Lewis, G., Schrire, B., MacKinder, B. & Lock, M., 2005. Legumes of the world. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 577 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.
- Sallenave, P., 1964. Propriétés physiques et mécaniques des bois tropicaux. Premier supplément. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 79 pp.
- Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan. 248 pp.
- UNEP-WCMC, 2006. Contribution to an evaluation of tree species using the new CITES Listing Criteria. UNEP World Conservation Monitoring Centre, Cambridge, United Kingdom. [Internet]. http://www.unep-wcmc.org/ species/tree_study/pdfs/ 1.pdf. November 2010.
- 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
- Breteler, F.J., 1999. A revision of Prioria, including Gossweilerodendron, Kingiodendron, Oxystigma, and Pterygopodium (Leguminosae - Caesalpinioideae - Detarieae) with emphasis on Africa. Wageningen Agricultural University Papers 99–3. 61 pp.
- Wilczek, R., Léonard, J., Hauman, L., Hoyle, A.C., Steyaert, R., Gilbert, G. & Boutique, R., 1952. Caesalpiniaceae. In: Robyns, W., Staner, P., Demaret, F., Germain, R., Gilbert, G., Hauman, L., Homès, M., Jurion, F., Lebrun, J., Vanden Abeele, M. & Boutique, R. (Editors). Flore du Congo belge et du Ruanda-Urundi. Spermatophytes. Volume 3. Institut National pour l’Étude Agronomique du Congo belge, Brussels, Belgium. pp. 234–554.
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., 2011. Prioria balsamifera (Vermoesen) Breteler. 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 17 September 2026.
- See the Prota4U database.