Schrebera alata (PROTA)

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Plant Resources of Tropical Africa
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Schrebera alata (Hochst.) Welw.


Protologue: Trans. Linn. Soc. London 27: 39 (1869).
Family: Oleaceae
Chromosome number: 2n = 44, 46

Origin and geographic distribution

Schrebera alata is widespread, from Eritrea and Ethiopia southwards through eastern DR Congo and East Africa to Angola, northern South Africa and Swaziland.

Uses

In Kenya the wood is mainly used for construction in house building, poles, furniture and tool handles. It is suitable for flooring, joinery, interior trim, mine props, vehicle bodies, sporting goods, toys, novelties, agricultural implements, turnery, pattern making, veneer and plywood. The wood is excellent as firewood, and is also used for charcoal production.

Several plant parts are used in traditional medicine. Pounded roots, twigs and leaves are chewed to treat tooth complaints and as antitussive, and in water they are applied as a wash to ulcers. Bark is also chewed to treat toothache, and bark decoctions are applied as anodyne. Leaves are chewed to treat tonsillitis, pharyngitis and headache, and leaf decoctions are administered as a vapour bath for treatment of headache and taken to treat colds, cough, fever, and as emetic, oxytocic and tonic. Schrebera alata is occasionally planted as ornamental tree.

Properties

The heartwood is whitish to pale brown, often with slightly darker streaks, not distinctly demarcated from the sapwood. The grain is straight to slightly wavy, texture fine and even. The wood is moderately heavy, with a density of 780–835 kg/m³ at 12% moisture content, hard and strong. It should be dried slowly and carefully to avoid serious splitting, checking and distortion. Once dry, it is moderately stable in service.

The wood saws and works fairly easily with both hand and machine tools. It planes to a smooth surface, and polishes well. Pre-boring is needed for nailing. The wood glues, paints and varnishes satisfactorily, and it turns fairly well. The heartwood is moderately durable. The sapwood is susceptible to Lyctus attack. The heartwood is resistant to preservatives.

Tests in rats showed that bark extracts have analgesic effects, confirming the use in traditional medicine, but they also demonstrated some toxicity, causing hepatic injuries.

Description

Deciduous, small to medium-sized tree up to 20(–25) m tall; bole usually short and crooked, up to 60 cm in diameter, often fluted; bark surface smooth or longitudinally fissured, sometimes flaking with thin scales, pale grey to yellowish brown, inner bark cream-coloured with orange markings, darkening upon exposure; crown fairly open; twigs initially hairy but becoming glabrous, with lenticels. Leaves opposite, imparipinnately compound with (3–)5(–7) leaflets; stipules absent; petiole 1–5 cm long, slightly winged; rachis 2–5 cm long, winged; leaflets opposite, nearly sessile, elliptical to obovate, 2–14 cm × 1–6 cm, cuneate and often asymmetrical at base, apex rounded to short-acuminate or occasionally notched, glabrous or sparsely short-hairy, pinnately veined with up to 10 pairs of lateral veins. Inflorescence a terminal cyme up to 10 cm long, glabrous to hairy, few-flowered to many-flowered. Flowers bisexual, regular, 5–7-merous, heterostylous, sweet scented; pedicel up to 3(–5) mm long; calyx campanulate, 2–4(–7) mm long, short-hairy; corolla white, sometimes flushed with pink, with reddish brown hairs at the base of lobes, tube funnel-shaped, 1–1.5 cm long, lobes 3–7 mm long, spreading; stamens 2, inserted in the upper part of the corolla tube, with short filaments; ovary superior, c. 1.5 mm in diameter, 2-celled, style slender, short or long. Fruit a pear-shaped or obovoid woody capsule 2–4.5 cm × 1–1.5 cm, pale brown, dehiscing with 2 valves, with up to 8 seeds. Seeds with a large wing, up to 2.5 cm × 1 cm.

Other botanical information

Young Schrebera alata trees grow fairly rapidly when they are planted in fertile soil. In Uganda young trees showed an annual growth of up to 1 m/year at 1500 altitude and on deep and moist soils, but growth was much less at higher altitudes and on drier sites. In southern Africa trees flower in December to February, and fruits ripen about 4 months after flowering. Fruits usually open while still attached to the tree. The seeds with their wings are dispersed by wind; they spin during falling.

Schrebera comprises about 8 species, of which 5 occur in tropical Africa including Madagascar, 2 in tropical Asia and 1 in South America. It seems most closely related to Comoranthus from Comoros and Madagascar, which also has a woody capsule.

Schrebera trichoclada

Schrebera trichoclada Welw. is a shrub or small tree up to 10 m tall with bole up to 30 cm in diameter, occurring from DR Congo and Tanzania southwards to Angola, Zimbabwe, Mozambique and Madagascar. Its wood is locally used for implements such as spoons. Bark and leaves are chewed as anodyne, leaf macerations are applied to the eyes to treat ophthalmia, and root infusions are used as an eye lotion.

Ecology

Schrebera alata occurs in evergreen forest, riverine forest, open woodland and sometimes savanna with scattered trees, up to 2500 m altitude. In East Africa it is often associated with Juniperus, Podocarpus and Olea spp., and occurs particularly in forest margins and clearings.

Management

Schrebera alata can be propagated by seeds and wildlings. Fruits should be harvested from the tree just before they open. They can be dried in the sun until they open and the seed can be collected. It is recommended to sow seeds with wings pointing upwards; they can be sown without pre-treatment. The seeds can be stored in a dry and cool locality for longer periods. Trees can be managed by coppicing and pruning, and intercropped with coffee.

Genetic resources

Schrebera alata is quite widespread in various habitats and not selectively harvested on a large scale. Therefore, there is no reason to consider it liable to genetic erosion.

Prospects

The wood of Schrebera alata will remain of some local importance, but it does not seem to have prospects for trade on the international market because the tree bole is usually too short and crooked or fluted. Schrebera alata has been recommended as a firewood crop for highland farmers in East Africa. It deserves more attention as an ornamental 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.
  • Chikamai, B.N., Githiomi, J.K., Gachathi, F.N. & Njenga, M.G., undated. Commercial timber resources of Kenya. Kenya Forestry Research Institute (KEFRI), Nairobi, Kenya. 164 pp.
  • 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.
  • 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.
  • SEPASAL, 2011. Schrebera alata. [Internet] Survey of Economic Plants for Arid and Semi-Arid Lands (SEPASAL) database. Royal Botanic Gardens, Kew, Richmond, United Kingdom. http://www.kew.org/ ceb/sepasal/. November 2011.

Other references

  • Beentje, H.J., 1994. Kenya trees, shrubs and lianas. National Museums of Kenya, Nairobi, Kenya. 722 pp.
  • Coates Palgrave, K., 2002. Trees of southern Africa. 3rd Edition. Struik Publishers, Cape Town, South Africa. 1212 pp.
  • Green, P.S., 2003. Oleaceae. In: Hedberg, I., Edwards, S. & Sileshi Nemomissa (Editors). Flora of Ethiopia and Eritrea. Volume 4, part 1. Apiaceae to Dipsacaceae. The National Herbarium, Addis Ababa University, Addis Ababa, Ethiopia and Department of Systematic Botany, Uppsala University, Uppsala, Sweden. pp. 79–86.
  • Kokwaro, J.O., 1993. Medicinal plants of East Africa. 2nd Edition. Kenya Literature Bureau, Nairobi, Kenya. 401 pp.
  • Kupicha, F.K., 1983. Oleaceae. In: Launert, E. (Editor). Flora Zambesiaca. Volume 7, part 1. Flora Zambesiaca Managing Committee, London, United Kingdom. pp. 300–327.
  • Liben, L., 1973. Oleaceae. In: Bamps, P. (Editor). Flore d’Afrique centrale. Spermatophytes. Jardin botanique national de Belgique, Brussels, Belgium. 36 pp.
  • Maundu, P., Berger, D., Saitabau, C., Nasieku, J., Kipelian, M., Mathenge, S., Morimoto, Y. & Höft, R., 2001. Ethnobotany of the Loita Maasai. Towards community management of the forest of the Lost Child. Experiences from the Loita Ethnobotany Project. UNESCO People and Plants Working Paper 8, Paris, France. 34 pp.
  • Mbaya, V.B., 1976. Hepatic changes induced by Schrebera alata (Hochst): a preliminary report on the toxicology of Il kau kawa. African Journal of Medicine and Medical Sciences 5(2): 131–137.
  • Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
  • Palmer, E. & Pitman, N., 1972–1974. Trees of southern Africa, covering all known indigenous species in the Republic of South Africa, South-West Africa, Botswana, Lesotho and Swaziland. 3 volumes. Balkema, Cape Town, South Africa. 2235 pp.

Author(s)

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

Correct citation of this article

Lemmens, R.H.M.J., 2012. Schrebera alata (Hochst.) Welw. In: 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. Accessed 2 August 2021.