Prota 7(2): Timbers/Bois d’œuvre 2
Sitz.-Ber. Bayer. Akad. 20: 242 (1890).
Origin and geographic distribution
Placodiscus pseudostipularis is distributed in Sierra Leone, Liberia, Côte d’Ivoire and Ghana.
In Liberia the wood of Placodiscus pseudostipularis is used for poles in house building and for tool handles. It has similar characteristics concerning quality and aspect as the wood of European walnut (Juglans regia L.), and is suitable for similar purposes such as first-class cabinet work and veneer. It is also used as firewood. The bark, soaked in water, is used as an embrocation to give relief to aching feet and legs.
The heartwood is pale to dark brown. The grain is usually straight, texture fine. The wood is fairly lustrous. It is heavy with a density of about 800–920 kg/m³ at 12% moisture content, hard and strong. The rates of shrinkage during drying are medium. Once dry, the wood is moderately stable in service. At 12% moisture content, the modulus of rupture is 131–153 N/mm², modulus of elasticity 17,540 N/mm², compression parallel to grain 49–57 N/mm², Janka side hardness 17,760 N and Chalais-Meudon side hardness 5.3–6.1. The wood is somewhat brittle and moderately difficult to saw and work due to its hardness, but can be finished smoothly. It is durable.
The leaves contain saponins and tannins.
Dioecious small tree up to 15 m tall; bole slender, often crooked or twisted, up to 30 cm in diameter; bark surface finely plated or covered with bumps and warts, greenish black, inner bark dark reddish brown; twigs glabrous. Leaves alternate, paripinnately compound with 2 pairs of leaflets, sessile; rachis 1–9 cm long; petiolules up to 8 mm long; leaflets ovate to elliptical, obovate or lanceolate, lower leaflets 2–6 cm × 1–4 cm, usually clasping stem and resembling stipules, upper leaflets 6–24 cm × 1.5–8 cm, cuneate at base, acuminate at apex, margins thickened, leathery, glabrous, pinnately veined with 7–12 pairs of lateral veins and with reticulate fine nervation. Inflorescence an axillary false raceme up to 35 cm long. Flowers unisexual, regular, pale green, nearly sessile; calyx with tube c. 3.5 mm long and wide, with 5 short lobes, hairy; petals absent; stamens 8, free; disk hairy; ovary superior, 3-lobed and 3-celled; male flowers with rudimentary ovary, female flowers with reduced stamens. Fruit a 1–2-lobed berry up to 3 cm long, short-hairy when young but becoming glabrous, yellow to orange when ripe, with fleshy whitish pulp, indehiscent, 1–2-seeded. Seeds ellipsoid, laterally flattened, pale brown. Seedling with hypogeal germination.
Other botanical information
Placodiscus comprises about 15 species and is restricted to tropical Africa. Even though most species are only small understorey trees, the wood is appreciated for its strength and resilience. This may be the case for at least the following species.
Placodiscus bancoensis Aubrév. & Pellegr. is a small tree up to 15 m tall, occurring locally in evergreen forest in Côte d’Ivoire and Ghana, where it is considered vulnerable. The bark has been used to treat asthma.
Placodiscus boya Aubrév. & Pellegr., a small to medium-sized tree up to 20 m tall, occurs in closed forest in Côte d’Ivoire and Ghana, where it can be quite common. The limited distribution area and the severe loss of its habitat render it vulnerable.
Placodiscus glandulosus Radlk. is a small forest tree of Nigeria, Cameroon and Gabon, having very strong heartwood.
Placodiscus paniculatus Hauman, a small to medium-sized tree up to 25 m tall and with a bole diameter up to 40 cm, is endemic to north-eastern DR Congo and considered vulnerable. The wood is reddish, very hard and used to manufacture arrows. The fruit is eaten.
Placodiscus riparius Keay is confined to riparian, flooded forest of Guinea Bissau, Guinea, Sierra Leone and Liberia, and is a small tree up to 10 m tall.
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); 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; 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; (70: fibres very thick-walled). Axial parenchyma: (78: axial parenchyma scanty paratracheal); 79: axial parenchyma vasicentric; (80: axial parenchyma aliform); (85: axial parenchyma bands more than three cells wide); 89: axial parenchyma in marginal or in seemingly marginal bands; 91: two cells per parenchyma strand; 92: four (3–4) cells per parenchyma strand. Rays: 96: rays exclusively uniseriate; (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: 136: prismatic crystals present; 138: prismatic crystals in procumbent ray cells; 142: prismatic crystals in chambered axial parenchyma cells.
(S. N’Danikou, P. Baas & H. Beeckman)
Growth and development
Placodiscus pseudostipularis grows slowly. In Côte d’Ivoire it flowers in July and fruits mature in February–March.
Placodiscus pseudostipularis occurs in the understorey of evergreen forest.
Propagation and planting
There are about 100 seeds per kg. The germination rate is quite high and germination starts 10–30 days after sowing.
In forest managed for commercial timber production Placodiscus pseudostipularis is usually considered and treated as a weed.
Placodiscus pseudostipularis is on the IUCN Red List as ‘endangered’. The effects of reduction in forest area in West Africa have been severe for this species.
For commercial timber producers Placodiscus pseudostipularis and other Placodiscus spp. are not very interesting because of the small size and often poor shape of the bole and their slow growth. They will remain of some local importance because of the excellent wood properties for special purposes such as high-quality cabinet work, or where durability is required for instance for poles in house building.
• Bouquet, A. & Debray, M., 1974. Plantes médicinales de la Côte d’Ivoire. Travaux et Documents No 32. ORSTOM, Paris, France. 231 pp.
• Chevalier, A., 1909. Les vegetaux utiles de l'Afrique tropicale francaise; etudes scientifiques et agronomiques. Volume 5. Augustin Challamel, Paris, France 314 pp.
• Cooper, G.P. & Record, S.J., 1931. The evergreen forests of Liberia. School of Forestry, Yale University, Bulletin 31, New Haven, United States. 153 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.
• 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.
• Burkill, H.M., 2000. The useful plants of West Tropical Africa. 2nd Edition. Volume 5, Families S–Z, Addenda. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 686 pp.
• de Koning, J., 1983. La forêt de Banco. Part 2: La Flore. Mededelingen Landbouwhogeschool Wageningen 83–1. Wageningen, Netherlands. 921 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.
• Fouilloy, R. & Hallé, N., 1973. Sapindacées. Flore du Cameroun. Volume 16. Muséum National d’Histoire Naturelle, Paris, France. 202 pp.
• Hall, J.B., 1980. New and little-known species of Placodiscus (Sapindaceae) in West Africa. Adansonia séries 2, 20(3): 287–295.
• Hauman, L., 1960. Sapindaceae. 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 9. Institut National pour l’Étude Agronomique du Congo belge, Brussels, Belgium. pp. 279–384.
• 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., 1998. Placodiscus pseudostipularis. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.2. [Internet] http://www.iucnredlist.org. Accessed July 2010.
• 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.
• Hegnauer, R., 1990. Chemotaxonomie der Pflanzen. Band 9. Birkhäuser Verlag, Basel, Switzerland. 786 pp.
• Keay, R.W.J., 1958. Sapindaceae. 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. 709–725.
• Ndjele, M.B., 1998. Placodiscus paniculatus. In: IUCN, 2010. IUCN Red List of Threatened Species. Version 2010.2. [Internet] http://www.iucnredlist.org. Accessed July 2010.
• Normand, D., 1955. Atlas des bois de la Côte d’Ivoire. Tome 2. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 132 pp.
Correct citation of this article:
Bosch, C.H., 2011. Placodiscus pseudostipularis Radlk. In: Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (Editors). Prota 7(2): Timbers/Bois d’œuvre 2. [CD-Rom]. PROTA, Wageningen, Netherlands.
wood in transverse section