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Dombeya torrida (J.F.Gmel.) Bamps

Protologue
Bull. Jard. Bot. Etat 32: 170 (1962).
Family
Sterculiaceae (APG: Malvaceae)
Chromosome number
2n = 60
Vernacular names
Forest dombeya (En).
Origin and geographic distribution
Dombeya torrida is distributed from Eritrea and Ethiopia southward through Central and East Africa to southern Malawi; it also occurs in Yemen.
Uses
The wood of Dombeya torrida is suitable for flooring, ship and boat building, vehicle bodies, furniture, handles and ladders, sporting goods, agricultural implements, yokes, poles and piles. In tropical Africa it is mainly used for bows, construction, poles, tool handles and spoons. In Tanzania logs are carved into traditional stools. Dombeya torrida is also used as firewood and for making charcoal.
Fibre from the bark is made into rope, string and cloth. The flowers produce good nectar for bees. Fallen leaves improve the soil. In East Africa a decoction of the flowers and bark is taken against indigestion.
Properties
The heartwood of Dombeya torrida is not clearly demarcated from the sapwood. The wood is uniformly pale brown, often with a central core of dark brown wood with olive streaks. The grain is usually straight, texture fine to medium.
The density of the wood is 705 kg/m³ at 11% moisture content. The wood is liable to checking in seasoning. It is strong and tough. At 11% moisture content, the modulus of rupture is 114 N/mm², compression parallel to grain 59 N/mm², Janka side hardness 6895 N and Janka end hardness 5560 N.
The wood saws and planes well and nails without splitting, but it is not suitable for turnery.
The durability of the wood is low to moderate. The sapwood is susceptible to attack by termites, marine borers and Lyctus borers. The sapwood and heartwood are moderately resistant to impregnation.
The fine hairs on the fruit may cause eye irritation.
Botany
Shrub or small to medium-sized tree up to 25 m tall; bole up to 120 cm in diameter, generally slightly curved or crooked; bark grey and smooth, slightly grooved with age, with lenticels; crown umbrella-shaped; young branches often red. Leaves alternate, simple; stipules 0.5–2.5 cm × 1–8 mm, caducous to persistent; petiole up to 20(–28) cm long; blade heart-shaped, very rarely lobed, 3–32(–42) cm × 2.5–23(–32) cm, base deeply cordate, apex acuminate, margin serrate, densely hairy especially on the reddish veins, basal veins 7–9. Inflorescence an axillary, 5.5–21.5 cm long, umbel-like cyme or 1–2 times bifurcate with umbel-like branches, many-flowered; peduncle 2–13(–17) cm long; branches up to 3(–5) cm long. Flowers bisexual, regular, 5-merous; pedicel 1–6 cm long; calyx with short tube, lobes 5–13 mm × 2–4 mm, hairy, often with long hairs basally; petals obliquely obovate, 8–21 mm × 7–20(–28) mm, white or pink, with or without red centre or red veins, persistent and papery in fruit; stamens up to 11 mm long, in 5 groups of 2–3(–4) alternating with 5 linear staminodes 4.5–13 mm long, all united into a red basal tube 1.5–7 mm long; ovary superior, globose or ovoid, hairy, 5-celled. Fruit an ovoid to globose capsule 4–10 mm long, long-hairy, up to 10-seeded. Seeds ovoid-oblong, 3(–4) mm × 2 mm, reddish brown to dark brown. Seedling with epigeal germination.
Dombeya comprises about 200 species, mainly distributed in Madagascar, with about 20 species in the African mainland. Dombeya torrida is an extremely variable species. Two subspecies have been distinguished:
– subsp. torrida (synonyms: Dombeya goetzenii K.Schum., Dombeya leucoderma K.Schum., Dombeya schimperiana A.Rich.): lower leaf surface densely hairy with a mixture of long-armed and short-armed stellate hairs, leaf blade usually abruptly narrowed to the apex; distributed from Yemen and Ethiopia southward to northern Tanzania.
– subsp. erythroleuca (K.Schum.) Seyani: lower leaf surface more sparsely hairy, predominantly with short-armed stellate hairs, leaf blade usually more gradually narrowed to the apex; distributed from northern Tanzania southward to southern Malawi.
The seed normally germinates in 15–20 days. Growth is fairly fast.
Ecology
Dombeya torrida occurs at 1600–3400 m altitude in forest, scrub, secondary bushland, grassland and cultivated land.
Management
Dombeya torrida can be propagated by seed. Seedlings are obtained either from the nursery or collected from the wild. There are about 235,000 seeds per kg. After drying the fruits in the sun for 2–3 days, the seeds are easily separated by rubbing or light threshing in a bag. Seed can be stored in airtight containers without seed treatment. Coppicing, lopping and pollarding of the tree are possible.
Genetic resources and breeding
In view of its wide distribution Dombeya torrida is not threatened with genetic erosion.
Prospects
The wood of Dombeya torrida is strong and tough but not durable. Furthermore the usefulness is limited due to the fact that the bole is seldom straight. Therefore it is unlikely to become more important.
Major references
• Beentje, H.J., 1994. Kenya trees, shrubs and lianas. National Museums of Kenya, Nairobi, Kenya. 722 pp.
• Bekele-Tesemma, A., Birnie, A. & Tengnäs, B., 1993. Useful trees and shrubs for Ethiopia: identification, propagation and management for agricultural and pastoral communities. Technical Handbook No 5. Regional Soil Conservation Unit/SIDA, Nairobi, Kenya. 474 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.
• Maundu, P. & Tengnäs, B. (Editors), 2005. Useful trees and shrubs for Kenya. World Agroforestry Centre - East and Central Africa Regional Programme (ICRAF-ECA), Technical Handbook 35, Nairobi, Kenya. 484 pp.
• Seyani, J.H., 1991. The genus Dombeya (Sterculiaceae) in continental Africa. Opera Botanica Belgica 2. National Botanic Garden of Belgium, Meise, Belgium. 186 pp.
Other references
• Dale, I.R. & Greenway, P.J., 1961. Kenya trees and shrubs. Buchanan’s Kenya Estates Limited, Nairobi, Kenya. 654 pp.
• Eggeling, W.J. & Dale, I.R., 1951. The indigenous trees of the Uganda Protectorate. Government Printer, Entebbe, Uganda. 491 pp.
• Fleuret, A., 1980. Nonfood uses of plants in Usambara. Economic Botany 34(4): 320–333.
• Hamill, F.A., Apio, S., Mubiru, N.K., Mosango, M., Bukenya-Ziraba, R., Maganyi, O.W. & Soejarto, D.D., 2000. Traditional herbal drugs of southern Uganda, 1. Journal of Ethnopharmacology 70: 281–300.
• Katende, A.B., Birnie, A. & Tengnäs, B., 1995. Useful trees and shrubs for Uganda: identification, propagation and management for agricultural and pastoral communities. Technical Handbook 10. Regional Soil Conservation Unit, Nairobi, Kenya. 710 pp.
• Kokwaro, J.O., 1993. Medicinal plants of East Africa. 2nd Edition. Kenya Literature Bureau, Nairobi, Kenya. 401 pp.
• 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 April 2006.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan, 248 pp.
• Wimbush, S.H., 1957. Catalogue of Kenya timbers. 2nd reprint. Government Printer, Nairobi, Kenya. 74 pp.
Author(s)
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands


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

Correct citation of this article:
Brink, M., 2007. Dombeya torrida (J.F.Gmel.) Bamps. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.