Prioria oxyphylla

Family

Caesalpiniaceae (Leguminosae - Caesalpinioideae)

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Synonyms

Pterygopodium oxyphyllum Harms (1913), Oxystigma oxyphyllum (Harms) J.Léonard (1950).

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Vernacular names

Tchitola (Fr). Tola chinfuta, tola mafuta (Po).

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Origin and geographic distribution

Prioria oxyphylla is distributed from southern Nigeria eastward to the Central African Republic, and south to DR Congo and Cabinda (Angola).

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Uses

The wood, known in trade as ‘tchitola’, is used for light construction, joinery, furniture, boxes, crates, shingles, veneer and plywood. It is suitable for light flooring, interior trim, vehicle bodies, railway sleepers, handles, ladders, toys, novelties, agricultural implements, turnery and pulpwood. The boles are traditionally used to make canoes. The thick and tough bark is used to make containers. The resin from the bark is heated to combat parasites such as lice and jiggers.

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Production and international trade

The timber of Prioria oxyphylla seems to be traded on the international market in small amounts only, although it may be traded in mixed consignments, e.g. together with tola (Prioria balsamifera (Vermoesen) Breteler). Gabon exports small amounts of Prioria oxyphylla wood, mainly as veneer. In 2006 small amounts of veneer were exported from Congo at an average price of US$ 359/m³.

Properties

The heartwood is pinkish brown to coppery brown, darkening to reddish brown upon exposure, with blackish streaks, and distinctly demarcated from the up to 10 cm wide, pale yellow-pink sapwood. An intermediate zone up to 12 cm wide is often present between sapwood and heartwood. The grain is straight or slightly interlocked, texture moderately coarse. The wood contains a greenish resin, becoming brownish to blackish upon exposure.
The wood is medium-weight, with a density of 580–670 kg/m³ at 12% moisture content, and moderately hard. It air dries fairly rapidly, with only slight tendency to distortion and checking. It should not be dried too rapidly because spots caused by resin may develop then. The rates of shrinkage are medium to high, from green to oven dry 3.7–4.6% radial and 8.0–13.1% tangential. Once dry, the wood is moderately stable to stable in service. At 12% moisture content, the modulus of rupture is 85–137 N/mm², modulus of elasticity 9310–14,960 N/mm², compression parallel to grain 37–72 N/mm², shear 14 N/mm², cleavage 14–17 N/mm, Janka side hardness 5560 N and Chalais-Meudon side hardness 3.2.
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. The resin content can be high and steam and hot water treatments are sometimes needed to reduce the amounts to manageable levels. The nailing and screwing properties are satisfactory, and the wood glues, paints and varnishes well when the surfaces are free of resin. 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 fairly resistant to fungi, termites and dry-wood borers, but susceptible to 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.

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Adulterations and substitutes

In Europe and the United States the veneer of Prioria oxyphylla is considered a substitute for that of walnut (Juglans regia L.) and jatoba or guapinol (Hymenaea courbaril L.), mainly used for furniture and decorative purposes.

Description

Evergreen, large tree up to 50 m tall; bole branchless for up to 20(–40) m, straight and cylindrical, up to 130(–300) cm in diameter, without buttresses; bark surface scaly with elongate scales, sometimes slightly fissured, grey to greenish grey, inner bark fibrous, pinkish to reddish; crown usually comparatively small, with sinuous branches; twigs glabrous. Leaves alternate, imparipinnately or paripinnately compound with (4–)6–8(–10) leaflets; stipules small, c. 3 mm long, very early caducous; petiole (0.5–)1–2(–2.5) cm long, rachis (4–)6–11 cm long; petiolules 3–6(–7) mm long; leaflets alternate, obliquely elliptical to ovate-elliptical, (3–)6–11 cm × (1)2–4.5 cm, cuneate to rounded at base, short-acuminate at apex, leathery, glabrous, pinnately veined with 6–11 pairs of lateral veins. Inflorescence an axillary compound raceme up to 20 cm long, with branches up to 15 cm long, short-hairy. Flowers bisexual, regular, yellowish white; pedicel 1–1.5 mm long; sepals 5, obovate-elliptical, 1.5–2 mm long, spreading or erect, usually hairy at margins only; petals absent; stamens 10, free, 2–5 mm long, filaments hairy; ovary superior, c. 1 mm long, densely hairy, 1-celled, style slender, slightly curved. Fruit an ovoid, flattened, indehiscent, 1-seeded pod with large wing at base, 6–11.5 cm × 2–4 cm, sometimes with numerous resin pockets, wing longitudinally and reticulately veined. Seed ellipsoid, flattened, up to 2.5 cm long. Seedling with hypogeal germination; epicotyl 9–17 cm long, with some small scales; first leaves alternate, with 2 leaflets.

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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 buchholzii (Harms) Breteler (synonym: Oxystigma buchholzii Harms, Oxystigma dewevrei De Wild.) is a medium-sized tree up to 30 m tall, with bole up to 75(–180) cm in diameter. It is found in periodically inundated forest along rivers from Cameroon east to DR Congo and south to northern Angola. It is characterized by glabrous inflorescences and unwinged fruits circular to obcordate-obovate in outline. Its wood is used for similar purposes as that of Prioria oxyphylla, e.g for joinery and traditionally for canoes.
Prioria mannii (Baill.) Breteler (synonym: Oxystigma mannii (Baill.) Harms) is a medium-sized tree up to 30 m tall, with bole up to 70 cm in diameter. It occurs in swamp forest along the coast from eastern Nigeria to northern Gabon. It resembles Prioria buchholzii, but differs in short-hairy inflorescences and more rough and dull fruits. Its wood is used for construction and utensils, and traditionally for canoes. It has similar properties as that of Prioria oxyphylla, but the density is slightly lower, about 510 kg/m³ at 12% moisture content, and it is slightly less hard and strong, and not durable.
Prioria msoo (Harms) Breteler (synonym: Oxystigma msoo Harms) is a large tree up to 40(–50) m tall, with bole up to 150(–300) cm in diameter. It is restricted to evergreen forest in Kenya and Tanzania. It differs from Prioria mannii in its sepals which are more hairy inside, and in its shortly winged fruits with longitudinal veins. Its wood is used in house building and for canoes, utensils, tool handles, carvings and plywood, and as firewood. It has similar properties as that of Prioria mannii, with a density of about 510 kg/m³ at 12% moisture content, and it is rather soft and not durable. The tree serves as forage for honey bees. Prioria msoo has been classified as vulnerable in the IUCN Red List.

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)); 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; 46: ≤ 5 vessels per square millimetre; (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: 79: axial parenchyma vasicentric; 80: axial parenchyma aliform; 81: axial parenchyma lozenge-aliform; 82: axial parenchyma winged-aliform; 83: axial parenchyma confluent; 86: axial parenchyma in narrow bands or lines up to three cells wide; 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). 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; 115: 4–12 rays per mm; 116: ≥ 12 rays per mm. Secretory elements and cambial variants: 129: axial canals diffuse. Mineral inclusions: 136: prismatic crystals present; 138: prismatic crystals in procumbent ray cells; 142: prismatic crystals in chambered axial parenchyma cells.
(S. N’Danikou, P.E. Gasson & E.A. Wheeler)

Growth and development

In DR Congo flowering and fruiting trees have been recorded throughout the year.

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Ecology

Prioria oxyphylla occurs in lowland rainforest on well-drained soils.

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Management

Prioria oxyphylla occurs scattered in the forest. In Cameroon and Gabon, it is apparently comparatively rare, but it is more common in Congo and DR Congo.

Harvesting

The minimum bole diameter allowed for harvesting is 60 cm in Cameroon, 70 cm in Gabon and 80 cm in the Central African Republic and DR Congo.

Yield

In DR Congo a bole of 39 m long and 110 cm in diameter yielded 19.8 m³ of wood.

Handling after harvest

Freshly harvested logs are sometimes attacked by pinhole borers, but immediate chemical protection of logs is usually not needed. They usually float in water and thus can be transported by river, but some logs sink because the density of green wood is close to 1000 kg/m³.

Genetic resources and breeding

Although Prioria oxyphylla has a fairly large area of distribution, it occurs scattered and is in many regions within its area of distribution uncommon. Like Prioria balsamifera, it suffered from habitat loss and heavy exploitation, but it is not classified on the IUCN Red List of endangered species like Prioria balsamifera. Monitoring of the populations of Prioria oxyphylla is recommended because it may become easily liable to genetic erosion.

Prospects

Prioria oxyphylla produces timber that is of great interest for the international market, but the volume of timber available seems to be limited. Information on growth rates and natural regeneration is needed to draw up directives for proper management practices to ensure sustainable production.

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), 1952. Tchitola. I - Fiche botanique et forestière. Bois et Forêts des Tropiques 23: 175–178.
• 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.

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Other references

• Aubréville, A., 1968. Légumineuses - Caesalpinioidées (Leguminosae - Caesalpinioideae). Flore du Gabon. Volume 15. Muséum National d’Histoire Naturelle, Paris, France. 362 pp.
• Beentje, H.J., 1994. Kenya trees, shrubs and lianas. National Museums of Kenya, Nairobi, Kenya. 722 pp.
• Brenan, J.P.M., 1967. Leguminosae, subfamily Caesalpinioideae. In: Milne-Redhead, E. & Polhill, R.M. (Editors). Flora of Tropical East Africa. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. 230 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. Tchitola. [Internet] Tropix 6.0. http://tropix.cirad.fr/ africa/ tchitola.pdf. Accessed April 2011.
• Fouarge, J., Gérard, G. & Sacré, E., 1953. Bois du Congo. Institut National pour l’Etude Agronomique du Congo belge (INEAC), Brussels, Belgium. 424 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.
• Lovett, J. & Clarke, G.P., 1998. Oxystigma msoo. In: IUCN. Red list of threatened species. Version 2010.4. [Internet] http://www.iucnredlist.org Accessed April 2011.
• Lovett, J.C., Ruffo, C.K., Gereau, R.E. & Taplin, J.R.D., 2006. 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/. Accessed April 2011.
• 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.
• Raponda-Walker, A. & Sillans, R., 1961. Les plantes utiles du Gabon. Paul Lechevalier, Paris, France. 614 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.
• 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.
• 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

• Aubréville, A., 1970. Légumineuses - Césalpinioidées (Leguminosae - Caesalpinioideae). Flore du Cameroun. Volume 9. Muséum National d’Histoire Naturelle, Paris, France. 339 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.
• 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)

•	R.H.M.J. Lemmens PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

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

Lemmens, R.H.M.J., 2011. Prioria oxyphylla (Harms) Breteler. [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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