Prota 7(1): Timbers/Bois d’œuvre 1
Bull. Jard. Bot. Etat 33: 263 (1963).
Bombacaceae (APG: Malvaceae)
Bombax rhodognaphalon K.Schum. (1895).
East African bombax, wild kapok tree (En). Msufi mwitu, msufi pori (Sw).
Origin and geographic distribution
Rhodognaphalon schumannianum is distributed in Kenya, Tanzania, Malawi and Mozambique. It is occasionally planted.
The wood is locally used for roofing, doors, panelling and cheap plywood for packing cases. The bole is traditionally used for dugout canoes. The wood is suitable for low-grade furniture, sporting goods, matches, hardboard, particle board and wood-wool. It is also suitable for pulping and for charcoal making.
The roasted seeds are eaten like groundnuts, and they are pounded and cooked with vegetables or meat. Floss from the fruit has been used for stuffing pillows, cushions and mattresses. The bark yields a red-brown dye and fibre for rope making. The roots are used to treat asthma, coughs and diarrhoea, the bark is a traditional medicine against diarrhoea and malaria, and the leaves are used in cleansing rituals. Rhodognaphalon schumannianum is used as a shade and wayside tree.
Production and international trade
The seeds are sold in local markets.
The heartwood is pale to dark pinkish brown with diffuse dark bands; it is indistinctly demarcated from the sapwood when freshly cut, but on drying the approximately 7.5 cm wide sapwood becomes cream-coloured. The grain is straight, texture medium to moderately coarse. Black gum ducts are sometimes present.
The density of the wood is (420–)465–480 (–580) kg/m³ at 12% moisture content. The wood dries rapidly with some surface checking and distortion, and occasional collapse. The rates of shrinkage from green to 12% moisture content are 2.0% radial and 3.5% tangential. Star shakes develop on drying. Once dry, the wood is fairly stable in service.
The wood is weak and soft. At 12% moisture content, the modulus of rupture is 47 N/mm², modulus of elasticity 6100 N/mm², compression parallel to grain 31 N/mm², shear 6 N/mm², cleavage 44 N/mm radial and 53 N/mm tangential, and Janka side hardness 2000 N.
Both the green and dry wood saw easily. The wood works easily with hand and machine tools. It takes nails well, but the holding power is low. It peels easily. Painting, staining and lacquering properties are poor. Veneers dry rapidly, with high shrinkage, and tend to be brittle.
The wood has low durability, being liable to attacks by sapstain fungi, marine borers and termites. The sapwood is liable to attack by Lyctus borers. The heartwood is extremely resistant to impregnation with preservatives.
The wood fibres have an average length of 1.9 mm, with a diameter of 25.4 μm. The chemical composition is: cellulose 50%, pentosans 8%, lignin 35% and ash 1%. The solubility in cold water is 1%, in hot water 2%, in alcohol-benzene 4% and in 1% NaOH 16%. Paper-making experiments in the 1950s resulted in papers with low strength.
Ethanol, petroleum ether and ethyl acetate extracts of the root bark have shown in-vitro antimalarial activity.
Medium-sized to fairly large tree up to 40 m tall; bole cylindrical, branchless for up to 21 m, up to 150 cm in diameter, buttresses up to 3 m high; bark surface smooth, yellow-green, on older trees sometimes scaly and grey. Leaves alternate, digitately compound, with (3–)5–7(–8) leaflets, central leaflet larger than other ones; stipules deciduous; petiole 3.5–12.5 cm long; petiolules 0.5–2 cm long; leaflets elliptical or obovate, 3–14 cm × 2–6 cm, cuneate or decurrent at base, acuminate at apex, margin entire, glabrous or stellate hairy, pinnately veined with 7–22 pairs of lateral veins. Inflorescence an axillary, 2–5-flowered fascicle, or flowers solitary. Flowers bisexual, regular, 5-merous; pedicel 6–25 mm long, glabrous or stellate hairy; calyx campanulate, truncate or slightly lobed, 6–14 mm × 7–11 mm, glabrous or stellate hairy outside, silky hairy inside; petals 5–11 cm × 1–6 cm, obtuse to acute at apex, red, pale yellow or white, hairy on both sides; stamens numerous, 4.5–7 cm long, fused to the petals at their base, united at their base into 5 bundles, red; ovary superior, ovoid, 2–4 mm long, hairy, 5-celled, style 5–11 cm long. Fruit an ellipsoid to obovoid capsule 5–13 cm × 2.5–4.5 cm, dehiscent with 5 valves, hairy or glabrescent, brown, many-seeded. Seeds globose or angular, 8–11 mm in diameter, glabrous, brown, embedded in reddish brown floss. Seedling with epigeal germination.
Rhodognaphalon comprises 3 species, all in tropical Africa. It was formerly included in Bombax, but it is now considered a separate genus, differing from Bombax in being unarmed, and having larger seeds, only 1 whorl of stamens and persistent calyx.
Within Rhodognaphalon schumannianum 2 varieties are distinguished:
– var. schumannianum (synonyms: Bombax rhodognaphalon K.Schum. var. rhodognaphalon, Rhodognaphalon tanganyikense A.Robyns), with leaves and pedicels glabrous; distributed in Kenya, Tanzania and Mozambique;
– var. tomentosum A.Robyns (synonyms: Bombax rhodognaphalon K.Schum. var. tomentosum A.Robyns; Bombax mossambicense A.Robyns; Bombax stolzii Ulbr., Rhodognaphalon mossambicense (A.Robyns) A.Robyns; Rhodognaphalon stolzii (Ulbr.) A.Robyns), with leaves and pedicels sparsely to densely stellate hairy; distributed in Mozambique.
Initial growth of Rhodognaphalon schumannianum is fairly fast. Three years after sowing, seedlings may be 2–3 m tall. In Tanzania the fruits ripen in October–December. The seeds are dispersed by wind, but most seeds do not spread further than 100 m from the tree.
Rhodognaphalon schumannianum occurs in wooded grassland, woodland and forest, from sea-level up to 1100 m altitude. The average annual rainfall in the area of distribution is normally not less than 1000 mm.
Rhodognaphalon schumannianum is easily propagated using seed. The 1000-seed weight is about 270 g. Fresh seeds normally germinate well, with germination taking 4–21 days. The seeds can be stored for up to 4 months, but are liable to attacks by insects and fungi. Seedlings are planted out when they are about 1 year old and 60–120 cm tall. Wild trees are locally protected. In Mozambique the minimum felling diameter is 50 cm, in Tanzania 55 cm.
Genetic resources and breeding
It is unclear to what extent Rhodognaphalon schumannianum is threatened with genetic erosion. It has been recorded as being at low risk / of least concern, and it is not included in the IUCN Red list.
Rhodognaphalon schumannianum is a multipurpose tree, yielding not only wood, but also food, fibre and traditional medicines. The wood has poor strength and durability characteristics, however, and the importance of Rhodognaphalon schumannianum as a source of timber is unlikely to increase.
• Beentje, H. & Smith, S., 2001. FTEA and after. Systematics and Geography of Plants 71(2): 265–290.
• 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.
• Bryce, J.M., 1967. The commercial timbers of Tanzania. Tanzania Forest Division, Utilisation Section, Moshi, Tanzania. 139 pp.
• Ruffo, C.K., Birnie, A. & Tengnäs, B., 2002. Edible wild plants of Tanzania. Technical Handbook No 27. Regional Land Management Unit/ SIDA, Nairobi, Kenya. 766 pp.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan, 248 pp.
• Beentje, H.J., 1989. Bombacaceae. In: Polhill, R.M. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. 9 pp.
• Beentje, H.J., 1994. Kenya trees, shrubs and lianas. National Museums of Kenya, Nairobi, Kenya. 722 pp.
• de Seabra, L. & Ferreirinha, M.P., 1950. Aspectos da anatomia, constituição química e valor papeleiro do lenho de Ricinodendron rautanenii Schinz e Bombax rhodognaphalon K.Schum. In: de Seabra, L. & Ferreirinha, M.P. Madeiras coloniais. Estudos, ensaios e documentos No 6. Ministério das Colónias, Junta de Investigações Coloniais, Lisboa, Portugal. pp. 23–52.
• Dowsett-Lemaire, F. & White, F., 1990. New and noteworthy plants from the evergreen forests of Malawi. Bulletin du Jardin botanique national de Belgique 60: 73–110.
• Gessler, M.C., Nkunya, M.H.H., Mwasumbi, L.B., Heinrich, M. & Tanner, M., 1994. Screening Tanzanian medicinal plants for antimalarial activity. Acta Tropica 56: 65–77.
• 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://www.york.ac.uk/ res/celp/webpages/projects/ecology/ tree%20guide/guide.htm. Accessed June 2008.
• Lutze, M., 2001. Aspekte des Holzmarktes und der holzbearbeitenden Industrie einiger ausgewählter Provinzen Mosambiks. PhD thesis. Wissenschaftszentrum Weihenstephan für Ernährung, Landnutzung und Umwelt, Technischen Universität München, Germany. 184 pp.
• Pakia, M. & Cooke, J.A., 2003. The ethnobotany of the Midzichenda tribes of the coastal forest areas in Kenya: 2. Medicinal plant uses. South African Journal of Botany 69(3): 382–395.
• Parry, N.S., 1956. Tree planting practices in tropical Africa. FAO Forestry Development Paper No 8. FAO, Rome, Italy. 302 pp.
• Williamson, J., 1955. Useful plants of Nyasaland. The Government Printer, Zomba, Nyasaland. 168 pp.
Correct citation of this article:
Brink, M., 2008. Rhodognaphalon schumannianum A.Robyns. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.