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Sterculia rhinopetala K.Schum.

Protologue
Engl., Monogr. afrik. Pflanzen-Fam. 5: 102 (1900).
Family
Sterculiaceae (APG: Malvaceae)
Chromosome number
2n = 36
Vernacular names
Brown sterculia, red sterculia (En).
Origin and geographic distribution
Sterculia rhinopetala occurs from Côte d’Ivoire to Cameroon.
Uses
The wood (trade names: lotofa, wawabima) is suitable for construction, flooring, joinery, interior trim, panelling, stairs, high-quality furniture, ship and boat building, tool handles, toys, turnery, poles, veneer and plywood. The wood is apparently suitable for paper making but is not as yet used for this purpose.
A mixture of the powdered bark and oil is applied to swellings and taken orally to counteract flatulence. The wood ash yields a vegetable salt that is used in cooking and in soap making.
Production and international trade
Cameroon exported about 2000 m³ of logs per year in 2000–2003, 960 m³ in 2004 and 1400 m³ in 2006. The same country exported 3725 m³ of sawn wood in 2003, 2060 m³ in 2004, and 4660 m³ in 2006. In 2003 Cameroon exported 4000 m³ of plywood, in 2005 about 2000 m³, and in 2006 also 2000 m³. Côte d’Ivoire exported about 5000 m³ of logs in 1983, Ghana 3150 m³ of logs in 1998.
Properties
The heartwood is pale to deep reddish brown, and distinctly demarcated from the 4–6 cm wide, white or creamish sapwood. The grain is straight or interlocked, texture medium to coarse. Growth rings are distinct. Quartersawn surfaces have an attractive figure.
The wood is moderately heavy, with a density of 720–890 kg/m³ at 12% moisture content. It air dries very slowly, with serious risk of distortion and checking. Boards 29 mm thick take about 22 weeks to air dry from green to 18% moisture content, boards 50 mm thick 41 weeks. To reduce the risk of checking during drying, it is recommended to quartersaw the wood. The rates of shrinkage from green to oven dry are high: 4.9–5.5% radial and 9.5–11.4% tangential. Once dry, the wood is moderately stable to unstable in service.
The wood is tough and hard. At 12% moisture content, the modulus of rupture is 116–186 N/mm², modulus of elasticity 13,400–18,700 N/mm², compression parallel to grain 57–81 N/mm², shear 14–15 N/mm², cleavage 25 N/mm, Janka side hardness 6180–8050 N and Janka end hardness 5830 N.
The wood saws and works easily with hand and machine tools, but tends to blunt tool edges and sawteeth. It finishes well, but a filler is needed. The wood holds nails and screws well, but pre-boring is recommended to avoid splitting on nailing. It glues well. The peeling and slicing properties are fairly good. Steam bending properties are moderate.
The wood is moderately durable. It is moderately resistant to termite attack, but pinhole borer attack sometimes occurs. The sapwood is susceptible to Lyctus borers. The heartwood is extremely resistant to impregnation with preservatives, the sapwood moderately resistant.
Adulterations and substitutes
The timber of Sterculia rhinopetala is often mixed with that of Heritiera utilis (Sprague) Sprague, from which it can be distinguished easily on microscopic characteristics.
Description
Deciduous fairly large tree up to 40 m tall; bole branchless for up to 21 m, up to 120 cm in diameter, straight, cylindrical, with narrow buttresses up to 3 m high; bark surface brown, rough-shaggy with rectangular scales, inner bark strongly resinous, red, often with vertical white bands, fibrous; crown narrow, branches whorled. Leaves alternate, simple and entire; stipules early caducous; petiole 3–11 cm long; blade oblong to lanceolate or oblanceolate, 10–30 cm × 4–16 cm, rounded at base, apex normally obtuse, with short brown stellate hairs when young, but glabrescent, pinnately veined with 10–14 pairs of lateral veins. Inflorescence an axillary panicle up to 20 cm long, densely hairy. Flowers unisexual, regular, 5-merous, pale or yellowish green; pedicel c. 5 mm long; perianth campanulate with lobes c. 1 mm × 1 mm, outside hairy; male flowers with 10 anthers in 2 rows borne on a short common stalk; female flowers with ovary consisting of 5 carpels united loosely. Fruit consisting of 1–5 woody follicles 5–7 cm long, many-seeded. Seeds c. 18 mm × 8 mm, with red fleshy seed coat, dangling from the open fruit on white threads. Seedling with epigeal germination.
Other botanical information
Sterculia is found throughout the tropics and comprises about 150 species, with about 25 of them in tropical Africa.
Sterculia foetida L. is a native of tropical Asia. It is a medium-sized tree of up to 30 m tall with digitately compound leaves. In Asia it is considered to produce better quality timber than other Sterculia spp. It has been introduced elsewhere in the tropics, primarily as an ornamental. In Ghana, Togo, Benin and Nigeria it is grown as an ornamental and the seeds are eaten after removal of the seed coat. The seeds contain 24–52% oil. The seeds have a purgative action and eating too many can cause headache and even abortion. In Kenya and Tanzania it seems to be restricted to botanic gardens, but in Mozambique it is widely grown as an ornamental.
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; 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; (42: mean tangential diameter of vessel lumina 100–200 μm); 43: mean tangential diameter of vessel lumina 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; 70: fibres very thick-walled. Axial parenchyma: (76: axial parenchyma diffuse); 78: axial parenchyma scanty paratracheal; 85: axial parenchyma bands more than three cells wide; 92: four (3–4) cells per parenchyma strand; (93: eight (5–8) cells per parenchyma strand). Rays: 99: larger rays commonly > 10-seriate; 102: ray height > 1 mm; (103: rays of two distinct sizes); 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; 114: 4 rays per mm. Storied structure: 120: axial parenchyma and/or vessel elements storied. Mineral inclusions: 136: prismatic crystals present; 137: prismatic crystals in upright and/or square ray cells; 138: prismatic crystals in procumbent ray cells; 140: prismatic crystals in chambered upright and/or square ray cells; 142: prismatic crystals in chambered axial parenchyma cells; (154: more than one crystal of about the same size per cell or chamber).
(N.P. Mollel, P. Détienne & E.A. Wheeler)
Growth and development
Sterculia rhinopetala is classified as a non-pioneer light demander. It grows slowly and is shade-tolerant. Annual bole diameter increment in secondary forest in Cameroon averaged 3.6 mm. In this forest some individuals were present in the main canopy, but the majority of individuals occurred as recruits in the lower storeys. In Côte d’Ivoire the annual increment in diameter was 3.3–7.3 mm in natural forest and 5.0–12.4 mm in a strongly thinned forest, but trees over 40 cm in bole diameter have slower diameter growth: about 2.5 mm per year. In Côte d’Ivoire 14-year-old planted trees showed a mean annual growth in diameter of 1 cm. In Côte d’Ivoire and Ghana flowering occurs when the tree is leafless between July and October and fruiting in the dry season. The seeds are dispersed by birds.
Ecology
Sterculia rhinopetala is found in the drier areas of lowland rain forests. Natural regeneration seems good. Under natural conditions, seedlings and saplings can be commonly found in small gaps in the forest, but slightly older trees become light demanders.
Propagation and planting
The 1000-seed weight is about 800 g. Multiplication of Sterculia rhinopetala using seeds is without problems with a rapid germination both in light and in darkness. Planting in full sun is possible. Germination starts after 4–12 days.
Management
In Cameroon the number of trees with a bole diameter over 60 cm ranged from 0.06 to 0.6 per ha and the volume of timber from 0.3 to 4.5 m³/ha. In the Mopri forest (Côte d’Ivoire) 14 Sterculia rhinopetala trees over 10 cm in diameter were counted per ha.
Diseases and pests
Sterculia rhinopetala is a host for cotton stainers (Dysdercus spp.), an important pest in cotton.
Harvesting
The minimum felling diameter is 50 cm in Cameroon and 70 cm in Ghana.
Yield
In Cameroon a tree 60 cm in diameter yields about 4.6 m³ of log, and a tree 100 cm in diameter 14.3 m³ of log.
Handling after harvest
The wood is sensitive to fungal attack during the air drying process.
Genetic resources
There are no indications that Sterculia rhinopetala is under threat of genetic erosion, but in many areas it is rather heavily exploited for its timber. Monitoring of its exploitation is recommended.
Prospects
The wood of Sterculia rhinopetala has good strength properties, but the tree grows slowly and the wood is difficult to dry and only moderately durable. Therefore it does not seem to have much potential as a plantation tree.
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., 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.
• CIRAD Forestry Department, 2003. Lotofa. [Internet] Tropix 5.0. http://tropix.cirad.fr/africa/lotofa.pdf . Accessed July 2008.
• Farmer, R.H., 1972. Handbook of hardwoods. 2nd Edition. Her Majesty’s Stationery Office, London, United Kingdom. 243 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.
• Irvine, F.R., 1961. Woody plants of Ghana, with special reference to their uses. Oxford University Press, London, United Kingdom. 868 pp.
• Phongphaew, P., 2003. The commercial woods of Africa. Linden Publishing, Fresno, California, United States. 206 pp.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan, 248 pp.
Other references
• Agyeman, V.K., Swaine, M.D. & Thompson, J., 1999. Responses of tropical forest tree seedlings to irradiance and the derivation of a light response index. Journal of Ecology 87: 815–827.
• ATIBT (Association Technique Internationale des Bois Tropicaux), 1986. Tropical timber atlas: Part 1 – Africa. ATIBT, Paris, France. 208 pp.
• Bertault, J.-G., 1982. Evolution de la surface terrière et de l’accroissement de la circonférence pour quatre essences du dispositif Sodefor de Mopri: aniégré (Aningeria robusta), lotofa (Sterculia rhinopetala), bossé (Guarea cedrata), ba (Celtis mildbraedii). Centre Technique Forestier Tropical, Abidjan, Côte d’Ivoire. 26 pp.
• Bertault, J.-G., Miézan, K., Dupuy, B., Durrieu de Madron, L. & Amsallem, I., 1999. Croissance et productivité en forêt dense humide après incendie: le dispositif de la Téné, Côte d’Ivoire (1978–1993). Document Forafri 20. Cirad-Forêt, Montpellier, France. 67pp.
• Chudnoff, M., 1980. Tropical timbers of the world. USDA Forest Service, Agricultural Handbook No 607, Washington D.C., United States. 826 pp.
• CTFT (Centre Technique Forestier Tropical), 1960. Lotofa. Information technique No 31. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 2 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.
• Durand, P.Y., 1978. Propriétés physiques et mécaniques des bois de Côte d’Ivoire: moyennes d’espèce et variabilité intraspécifique. Centre Technique Forestier Tropical, Abidjan, Côte d’Ivoire. 70 pp.
• Durand, P.Y., 1983. Séchage naturel du lotofa (Sterculia rhinopetala). Centre Technique Forestier Tropical, Abidjan, Côte d’Ivoire. 26 pp.
• Durrieu de Madron, L., Favrichon, V., Dupuy, B., Bar-Hen, A., Houde, L. & Maître, H.-F., 1998. Croissance et productivité en forêt dense humide: bilan des expérimentations dans le dispositif de Mopri, Côte d’Ivoire. Document Forafri 3. Cirad, Montpellier, France. 73 pp.
• Duviard, D., 1981. Les Dysdercus du cotonnier en Afrique Occidentale: écologie et migrations. Travaux et Documents de l’ORSTOM 135. ORSTOM, Paris, France. 172 pp.
• InsideWood, undated. [Internet] http://insidewood.lib.ncsu.edu/search/. Accessed May 2007.
• Keay, R.W.J., 1958. Sterculiaceae. 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. 310–332.
• Lancaster, P.C., 1961. Experiments with natural regeneration in the Omo forest reserve. Nigerian Forestry Information Bulletin 13: 5–16.
• Lemmens, R.H.M.J., Alonzo, D.S. & Sudo, S., 1995. Sterculia L. In: Lemmens, R.H.M.J., Soerianegara, I. & Wong, W.C. (Editors). Plant Resources of South-East Asia No 5(2). Timber trees: Minor commercial timbers. Backhuys Publishers, Leiden, Netherlands. pp. 423–435.
• 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.
• Parant, B., Boyer, F., Chichignoud, M. & Curie, P., 2008. Présentation graphique des caractères technologiques des principaux bois tropicaux. Tome 1. Bois d’Afrique. Réédition. CIRAD-Fôret, Montpellier, France. 186 pp.
• Riddoch, I., Grace, J., Fasehun, F.E., Riddoch, B. & Ladipo, D.O., 1991. Photosynthesis and successional status of seedlings in a tropical semi-deciduous rain forest in Nigeria. Journal of Ecology 79(2): 491–503.
• Sallenave, P., 1955. Propriétés physiques et mécaniques des bois tropicaux de l’Union française. Centre Technique Forestier Tropical, Nogent sur Marne, France. 129 pp.
• Vivien, J. & Faure, J.J., 1985. Arbres des forêts denses d’Afrique Centrale. Agence de Coopération Culturelle et Technique, Paris, France. 565 pp.
• Worbes, M., Staschel, R., Roloff, A. & Junk, W.J., 2003. Tree ring analysis reveals age structure, dynamics and wood production of a natural forest stand in Cameroon. Forest Ecology and Management 173: 105–123.
Sources of illustration
• 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.
• Vivien, J. & Faure, J.J., 1985. Arbres des forêts denses d’Afrique Centrale. Agence de Coopération Culturelle et Technique, Paris, France. 565 pp.
Author(s)
C.H. Bosch
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-DIR / B (Bât. C, Bur. 113), 34398 Montpellier Cedex 5, France


Editors
D. Louppe
CIRAD, Département Environnements et Sociétés, Cirad es-dir, Campus international de Baillarguet, TA C-DIR / B (Bât. C, Bur. 113), 34398 Montpellier Cedex 5, France
A.A. Oteng-Amoako
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
General editors
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
L.P.A. Oyen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
J.R. Cobbinah
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:
Bosch, C.H. & Louppe, D., 2008. Sterculia rhinopetala K.Schum. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.
Distribution Map wild


1, base of bole; 2, leaf; 3, part of fruit.
Redrawn and adapted by Achmad Satiri Nurhaman



leaves, fruits and seeds


opened fruits and seeds


opened fruit and seeds


wood


wood in transverse section


wood in tangential section


wood in radial section