Schrebera arborea

Family

Oleaceae

Synonyms

Vernacular names

Pau goiaba (Po).

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Origin and geographic distribution

Schrebera arborea is quite widespread, from Senegal and Guinea Bissau eastwards to southern Sudan and Uganda, and south to DR Congo.

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Uses

The wood is used for general construction, railway sleepers, boat-keels, utensils, tool handles, shafts and beehives. It is suitable for flooring, joinery, interior trim, mine props, vehicle bodies, furniture, sporting goods, toys, novelties, agricultural implements, turnery, pattern making, veneer and plywood. It is also used as firewood and for charcoal production.
In traditional medicine, fresh twigs are an ingredient of a preparation that is taken to treat skin diseases. Macerations of the twigs are administered as purgative to treat abdominal pain. In Nigeria the seeds are applied to the heads of children to treat skin complaints. In Uganda several plant parts are used as purgative.

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Production and international trade

The wood of Schrebera arborea is only used locally and not traded on the international timber market.

Properties

The heartwood is pinkish to yellowish brown, sometimes with violet streaks, and not distinctly demarcated from the paler sapwood. The grain is straight to wavy, texture usually fine. The wood is moderately heavy, with a density of 750–830(–930) kg/m³ at 12% moisture content, tough and quite hard. It air dries well, but care should be taken to avoid surface checking. The rates of shrinkage are rather high, from green to oven dry 4.7–5.6% radial and 7.8–8.6(–9.5)% tangential. Logs may either be back-sawn or quarter-sawn after felling. Once dry, the wood is unstable in service. At 12% moisture content, the modulus of rupture is (77–) 108–132 N/mm², modulus of elasticity 11,800 N/mm², compression parallel to grain 44–63 N/mm², shear 12–14 N/mm², cleavage 14.5–23.5 N/mm and Chalais-Meudon side hardness 2.7–3.6.
The wood is fairly easy to saw and work. In planing, picking-up of grain can be problematic, but it can be polished to a smooth finish. For nailing, pre-boring is recommended to avoid splitting. The gluing properties are satisfactory. The wood is easy to wax, paint and varnish. The heartwood is fairly durable, but occasionally susceptible to wood-boring beetles. The sapwood is liable to Lyctus attack. The heartwood is moderately resistant to preservatives.

Description

Deciduous, medium-sized tree up to 30(–40) m tall; bole branchless for up to 20(–30) m, straight and cylindrical, up to 80 cm in diameter, with small buttresses or fluted at base; bark surface smooth but flaking with thin scales, yellowish white to greyish brown with paler patches, inner bark fibrous, mottled cream and orange, darkening upon exposure; crown rounded; twigs initially hairy but becoming glabrous, with lenticels. Leaves opposite, simple and entire; stipules absent; petiole 1–5 cm long; blade elliptical to ovate, 5–15 cm × 3–10 cm, cuneate to rounded at base, acute to short-acuminate at apex, thinly leathery, glabrous or nearly so, pinnately veined with 6–12 pairs of lateral veins. Inflorescence a terminal or axillary cyme up to 10 cm long, few-flowered. Flowers bisexual, regular, (4–)5–8-merous, heterostylous, sweet-scented; pedicel 3–7 mm long; calyx campanulate, 3–5 mm long, slightly hairy or glabrous; corolla white to greenish white with purplish brown hairs at the base of lobes, tube funnel-shaped, 1–2 cm long, lobes c. 6 mm long, spreading; stamens 2, inserted in the upper part of the corolla tube, with short filaments; ovary superior, c. 1 mm in diameter, 2-celled, style slender, short or long. Fruit a pear-shaped woody capsule up to 6.5 cm × 3.5 cm, purplish brown with paler lenticels, dehiscing with 2 valves, usually with 4 fertile seeds. Seeds with a large wing, up to 4(–5) cm × 1 cm. Seedling with epigeal germination; hypocotyl c. 3 cm long, epicotyl c. 1 cm long, glabrous; cotyledons fleshy, flattened, c. 1.5 cm long; first leaves opposite.

Other botanical information

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 arborea has been included in Schrebera golungensis Welw., but the latter is probably a synonym of Schrebera trichoclada Welw.

Anatomy

Wood-anatomical description (IAWA hardwood codes):
Growth rings: 2: growth ring boundaries indistinct or absent. Vessels: 5: wood diffuse-porous; (10: vessels in radial multiples of 4 or more common); 13: simple perforation plates; 22: intervessel pits alternate; (23: shape of alternate pits polygonal); 24: intervessel pits minute (≤ 4 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; 48: 20–40 vessels per square millimetre. Tracheids and fibres: 61: fibres with simple to minutely bordered pits; (62: fibres with distinctly bordered pits); 65: septate fibres present; 66: non-septate fibres present; 69: fibres thin- to thick-walled; 70: fibres very thick-walled. Axial parenchyma: 75: axial parenchyma absent or extremely rare; 78: axial parenchyma scanty paratracheal; (92: four (3–4) cells per parenchyma strand); 93: eight (5–8) cells per parenchyma strand. Rays: 97: ray width 1–3 cells; (100: rays with multiseriate portion(s) as wide as uniseriate portions); 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); 115: 4–12 rays per mm. Mineral inclusions: 136: prismatic crystals present; 137: prismatic crystals in upright and/or square ray cells; (138: prismatic crystals in procumbent ray cells); 151: styloids and/or elongated crystals.
(F.D. Kamala, P. Baas & H. Beeckman)

Growth and development

In Senegal the growth of planted seedlings was quite slow; they reached on average 2.6 m in height 5 years after planting. In Côte d’Ivoire flowering trees have mainly been recorded in October–November and ripe fruits in February–March and November. In Nigeria trees flower in March–May and fruits ripen in April–June and December. Fruits usually open while still attached to the tree. The seeds with their wings are dispersed by wind; they spin during falling.

Ecology

Schrebera arborea occurs mostly in dry deciduous forest and semi-deciduous forest, up to 1500 m altitude. It is occasionally found in thickets in savanna regions and at forest edges, and in Uganda it occurs in mixed rainforest.

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Propagation and planting

Schrebera arborea is propagated by seed and wildlings. Mature fruits should be collected from the tree before dehiscence. They are usually dried in the sun until they open to collect the seeds. There are about 10,000 seeds per kg. Seeds can be stored for some time in a dry and cool locality. It is recommended to sow seeds with wings up; they can be sown without pre-treatment. They start germinating 2–4 weeks after sowing, with a moderate germination rate.

Management

In most regions within the distribution area of Schrebera arborea, trees occur scattered and are not common in the forest. They are sometimes planted in banana and cocoa plantations. Planted trees can be managed by coppicing and pollarding.

Genetic resources and breeding

Schrebera arborea is widespread and harvested on a moderate scale only. Therefore, it is unlikely to be threatened by genetic erosion notwithstanding being uncommon. It has been recorded as endangered in Togo and it is rare in Ghana.

Prospects

Although Schrebera arborea is considered a valuable timber tree of local importance, very little information is available on its growth rates and proper management practices. It deserves further research as a potential multipurpose species that could be useful in agroforestry systems. In Uganda Schrebera arborea has been recommended for planting as ornamental tree and as shade tree in coffee, cocoa and banana plantations.

Major references

• Aubréville, A., 1959. La flore forestière de la Côte d’Ivoire. Deuxième édition révisée. Tome troisième. Publication No 15. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 334 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.
• Burkill, H.M., 1997. The useful plants of West Tropical Africa. 2nd Edition. Volume 4, Families M–R. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 969 pp.
• Irvine, F.R., 1961. Woody plants of Ghana, with special reference to their uses. Oxford University Press, London, United Kingdom. 868 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.
• Keay, R.W.J., 1989. Trees of Nigeria. A revised version of Nigerian trees (1960, 1964) by Keay, R.W.J., Onochie, C.F.A. & Stanfield, D.P. Clarendon Press, Oxford, United Kingdom. 476 pp.
• Liben, L., 1973. Oleaceae. In: Bamps, P. (Editor). Flore d’Afrique centrale. Spermatophytes. Jardin botanique national de Belgique, Brussels, Belgium. 36 pp.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan. 248 pp.
• Turrill, W.B., 1952. Oleaceae. In: Turrill, W.B. & Milne-Redhead, E. (Editors). Flora of Tropical East Africa. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. 31 pp.
• Vivien, J. & Faure, J.J., 1985. Arbres des forêts denses d’Afrique Centrale. Agence de Coopération Culturelle et Technique, Paris, France. 565 pp.

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Other references

• Adjanohoun, E.J., Ahyi, A.M.R., Aké Assi, L., Baniakina, J., Chibon, P., Cusset, G., Doulou, V., Enzanza, A., Eymé, J., Goudoté, E., Keita, A., Mbemba, C., Mollet, J., Moutsamboté, J.-M., Mpati, J. & Sita, P. (Editors), 1988. Médecine traditionnelle et pharmacopée - Contribution aux études ethnobotaniques et floristiques en République Populaire du Congo. Agence de Coopération Culturelle et Technique, Paris, France. 606 pp.
• Adjanohoun, E.J., Adjakidjè, V., Ahyi, M.R.A., Aké Assi, L., Akoègninou, A., d’Almeida, J., Apovo, F., Boukef, K., Chadare, M., Cusset, G., Dramane, K., Eyme, J., Gassita, J.N., Gbaguidi, N., Goudote, E., Guinko, S., Houngnon, P., Lo, I., Keita, A., Kiniffo, H.V., Kone-Bamba, D., Musampa Nseyya, A., Saadou, M., Sodogandji, T., De Souza, S., Tchabi, A., Zinsou Dossa, C. & Zohoun, T., 1989. Contribution aux études ethnobotaniques et floristiques en République Populaire du Bénin. Agence de Coopération Culturelle et Technique, Paris, France. 895 pp.
• Akoègninou, A., van der Burg, W.J. & van der Maesen, L.J.G. (Editors), 2006. Flore analytique du Bénin. Backhuys Publishers, Leiden, Netherlands. 1034 pp.
• Aubréville, A., 1950. Flore forestière soudano-guinéenne. Société d’Editions Géographiques, Maritimes et Coloniales, Paris, France. 533 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.
• Eggeling, W.J. & Dale, I.R., 1951. The indigenous trees of the Uganda Protectorate. Government Printer, Entebbe, Uganda. 491 pp.
• Garzuglia, M., 2006. Global Forest Resources Assessment 2005: Threatened, endangered and vulnerable tree species. [Internet] A comparison between FRA 2005 and the IUCN Red List. ftp://ftp.fao.org/docrep/fao/010/ah886e/ah886e00.pdf. Accessed November 2011.
• Green, P.S., 1963. Oleaceae. In: Hepper, F.N. (Editor). Flora of West Tropical Africa. Volume 2. 2nd Edition. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. pp. 47–51.
• 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.
• Idu, M., Erhabor, J.O. & Efijuemue, H.M., 2010. Documentation on medicinal plants sold in markets in Abeokuta, Nigeria. Tropical Journal of Pharmaceutical Research 9(2): 110–118.
• 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.
• Louppe, D., 1993. Espèces ligneuses soudaniennes et soudano-guinéennes intéressantes. Revue bibliographique. IDEFOR-DFO, Korhogo, Côte d’Ivoire. 43 pp.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
• 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.
• Tailfer, Y., 1989. La forêt dense d’Afrique centrale. Identification pratique des principaux arbres. Tome 2. CTA, Wageningen, Pays-Bas. pp. 465–1271.
• Taylor, C.J., 1960. Synecology and silviculture in Ghana. Thomas Nelson and Sons, Edinburgh, United Kingdom. 418 pp.
• Wallander, E. & Albert, V.A., 2000. Phylogeny and classification of Oleaceae based on rps16 and trnL-F sequence data. American Journal of Botany 87(12): 1827–1841.

Sources of illustration

• Keay, R.W.J., 1989. Trees of Nigeria. A revised version of Nigerian trees (1960, 1964) by Keay, R.W.J., Onochie, C.F.A. & Stanfield, D.P. Clarendon Press, Oxford, United Kingdom. 476 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)

•	S. Pentsil Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
•	E.A. Obeng Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Editors

•	R.H.M.J. Lemmens 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 105 / D (Bât. C, Bur. 113), 34398 Montpellier Cédex 5, France
•	A.A. Oteng-Amoako Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Associate editors

•	E.A. Obeng 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

Pentsil, S. & Obeng, E.A., 2012. Schrebera arborea A.Chev. [Internet] Record from PROTA4U. 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. <http://www.prota4u.org/search.asp>. Accessed .

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