Celtis zenkeri

Family

Celtidaceae (APG: Cannabaceae)

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Synonyms

Celtis soyauxii Engl. (1900).

Vernacular names

Origin and geographic distribution

Celtis zenkeri occurs from Guinea eastward to southern Sudan and Ethiopia and southward to DR Congo, Tanzania and Angola.

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Uses

The wood of Celtis zenkeri, traded as ‘ohia’ or ‘African celtis’, is used for construction, especially in house building, for flooring and traditionally for poles, pestles and tool handles. It is suitable for joinery, interior trim, vehicle bodies, furniture, ladders, sporting goods, toys, novelties, agricultural implements, turnery, veneer and plywood. It is regarded as excellent firewood.
In Nigeria the leaves are recorded to be edible and they also serve as fodder for livestock. Various parts of the plant are used in traditional medicine. In southern Nigeria a preparation made from the macerated wood is applied to cuts on the skin. Bark decoctions are drunk to treat cough, and powdered bark with palm oil is rubbed on the body to ease pain associated with epilepsy, whereas in Côte d’Ivoire leaves are applied for the same purpose. Leaf preparations are applied to the legs for the treatment of elephantiasis. The tree produces large quantities of litter which decays readily after fall and serves as a good green manure.

Production and international trade

Côte d’Ivoire and Ghana are the main exporting countries, but volumes are small. In 2005 Ghana exported 4000 m³ of Celtis veneer at an average price of US$ 310, in 2006 3000 m³ at US$ 363, and in 2009 3100 m³ of rotary veneer, 80 m³ of sliced veneer and 120 m³ of plywood. The wood is regarded as valuable in local markets.

Properties

The heartwood is whitish to pale yellowish or greyish, darkening to pale brown upon exposure, and indistinctly demarcated from the sapwood. Patches of black or brown changing to pale green with age may be seen in some logs. The grain is straight or interlocked, texture fine but locally rather coarse. Freshly cut wood has a ‘sugar-like’ odour.
The wood is medium-weight to fairly heavy, with a density of 610–920 kg/m³ at 12% moisture content, and is fairly hard. It air dries and kiln dries slowly but well, with little degrade, although some reports mention a risk of distortion and end splitting. The rates of shrinkage are moderate, from green to oven dry 4.9–5.5% radial and 8.0–9.1% tangential. Once dry, the wood is moderately stable to unstable in service.
At 12% moisture content, the modulus of rupture is (97–)125–182(–203) N/mm², modulus of elasticity 11,750–17,050 N/mm², compression parallel to grain 43–71 N/mm², shear 22 N/mm², cleavage 16–19 N/mm, Janka side hardness 7470 N and Chalais-Meudon side hardness 3.6–5.4.
The wood works fairly well with both machine and hand tools, but difficulty is experienced in wood with black or brown patches, which have a strong blunting effect on cutting edges. In planing operations, a reduced cutting angle is advised to prevent tearing along the grain. Nailing and screwing are quite difficult, and pre-boring is required. Moulding, mortising and carving properties are good. The wood glues and finishes well when a filler is used. It has good resistance to abrasion and moderate steam-bending properties. The turning properties are better than in other Celtis species. Veneering properties are satisfactory, but steaming is needed; drying of veneer does not pose problems. The wood is of low durability. It is susceptible to attack by blue-stain fungi and many insects. The wood is permeable to preservatives under pressure, but poor results are obtained when hot and cold tank treatments are used. Saw dust may cause irritation in wood workers.
The wood contains about 39% cellulose, 25% lignin, 25% pentosan, 2.1% ash and 0.01% silica. The solubility is 2.1% in alcohol-benzene, 2.8% in hot water and 25.7% in a 1% NaOH solution.

Adulterations and substitutes

The wood of Celtis zenkeri is similar in appearance and properties to that of Celtis mildbraedii Engl. and Celtis gomphophylla Baker; they are all traded as ‘ohia’ or ‘African celtis’. It is also similar to that of Celtis adolfi-friderici Engl., which may also be traded as ‘African celtis’.

Description

Deciduous, medium-sized tree up to 30(–50) m tall; bole branchless for up 15(–20) m, slender, straight or twisted, up to 80(–120) cm in diameter, often irregularly fluted and with sharp buttresses up to 3 m high; bark surface smooth, scaling in round patches, silvery grey to yellowish or pale brown, inner bark fibrous, dark brown with yellow to off-white layers; crown dense, slightly spreading; twigs densely brownish short-hairy. Leaves alternate, simple; stipules ovate-lanceolate, 5–7 mm long, short-hairy, caducous; petiole 5–8 mm long; blade ovate to oblong-elliptical, 6–15 cm × 3.5–8 cm, base obliquely cuneate to rounded, apex acuminate, margins usually entire, papery to thin-leathery, soft reddish-brown hairy below, 3-veined from the base and additionally with 2–4 pairs of lateral veins. Inflorescence an axillary cyme 1–5 cm long, short-hairy, many-flowered. Flowers unisexual or bisexual, regular, usually 5-merous, small, greenish, nearly sessile; tepals 2–3 mm long, hairy; stamens free, incurved in bud and later spreading; ovary superior, ovoid, brownish hairy, 1-celled, styles 2, 2-lobed; male flowers numerous and densely clustered, with rudimentary ovary; female flowers and/or bisexual flowers at tops of upper inflorescences, female flowers with rudimentary stamens. Fruit a globose to ovoid drupe 0.5–1 cm long, reddish when ripe, glabrous, crowned at top by remains of styles; stone ovoid-polygonal, c. 5 mm long, rough, 1-seeded. Seedling with epigeal germination; hypocotyl 3–4 cm long, epicotyl c. 1 cm long, hairy; cotyledons leafy, c. 1.5 cm long, 2-lobed at apex; first leaves alternate.

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Other botanical information

Celtis comprises about 100 species and is widespread in all tropical, subtropical and temperate regions. For tropical Africa 11 species have been recorded, 2 of which are endemic to Madagascar. Celtis is taxonomically a difficult genus, showing much morphological variability. Traditionally, it has been treated as part of the family Ulmaceae, but later it was often considered to belong to a separate family, Celtidaceae, whereas from most recent research it was proposed to take up the latter family in Cannabaceae.
Celtis zenkeri resembles Celtis mildbraedii Engl. and these species have been confused in the literature; they have both been called Celtis soyauxii Engl., which is now considered a synonym of Celtis zenkeri. Celtis mildbraedii usually has toothed leaves with reticulate tertiary veins (straight and parallel in Celtis zenkeri), and rhomboid fruit stones.
Celtis tessmannii Rendle (synonym: Celtis brieyi De Wild.) is a medium-sized to fairly large tree up to 40 m tall with bole up to 100 cm in diameter, occurring in Cameroon, Equatorial Guinea, Gabon, Congo and DR Congo. Its yellowish wood, which has a density of 620–790 kg/m³ at 12% moisture content, resembles that of Celtis zenkeri, has similar technical characteristics and is suitable for similar purposes. In traditional medicine, the bark and roots are administered as anodyne. Bark preparations are taken to treat diarrhoea and fever, whereas leaf preparations are used in the treatment of inflammation of the respiratory organs, tachycardia and anaemia.
Celtis toka (Forssk.) Hepper & J.R.I.Wood (synonym: Celtis integrifolia Lam.) is a small to medium-sized tree up to 25 m tall with short bole up to 6 m long and 100 cm in diameter, occurring in dry forest and savanna from Senegal eastward to Ethiopia and Kenya, and in Yemen. Its yellowish white wood also resembles that of Celtis zenkeri and is suitable for similar purposes such as construction, handles, implements and canoes, although it appears to have a lower density (about 560 kg/m³ at 12% moisture content) and to be less hard. It is also used as firewood. Young leaves are eaten as a vegetable and the fruits are also edible. The foliage is browsed by livestock. The fibrous bark is used to make mattings and rope. Bark preparations are used to treat rheumatism, and root preparations to treat rheumatism, paralysis and sterility, and as a tonic. Leaf decoctions are administered as a treatment for measles, headache, rheumatism, smallpox and oedema, and to promote childbirth, whereas leaf powder is applied to wounds and abscesses. Celtis toka is planted as ornamental shade tree. It is a multipurpose tree which has been promoted for planting in the Sahel region.

Anatomy

Wood-anatomical description (IAWA hardwood codes):
Growth rings: 1: growth ring boundaries distinct; 2: growth ring boundaries indistinct or absent. Vessels: 5: wood diffuse-porous; 13: simple perforation plates; 22: intervessel pits alternate; 23: shape of alternate pits polygonal; 25: intervessel pits small (4–7 μm); 26: intervessel pits medium (7–10 μm); 30: vessel-ray pits with distinct borders; similar to intervessel pits in size and shape throughout the ray cell; 31: vessel-ray pits with much reduced borders to apparently simple: pits rounded or angular; 41: mean tangential diameter of vessel lumina 50–100 μm; 42: mean tangential diameter of vessel lumina 100–200 μm; 47: 5–20 vessels per square millimetre; 56: tyloses common. Tracheids and fibres: 61: fibres with simple to minutely bordered pits; 66: non-septate fibres present; 69: fibres thin- to thick-walled; 70: fibres very thick-walled. Axial parenchyma: 80: axial parenchyma aliform; 82: axial parenchyma winged-aliform; 83: axial parenchyma confluent; (85: axial parenchyma bands more than three cells wide); 86: axial parenchyma in narrow bands or lines up to three cells wide; 92: four (3–4) cells per parenchyma strand; 93: eight (5–8) cells per parenchyma strand. Rays: 97: ray width 1–3 cells; 98: larger rays commonly 4- to 10-seriate; 107: body ray cells procumbent with mostly 2–4 rows of upright and/or square marginal cells; (108: body ray cells procumbent with over 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; 142: prismatic crystals in chambered axial parenchyma cells; 144: druses present; 145: druses in ray parenchyma cells.
(F.D. Kamala, H. Beeckman & P. Baas)

Growth and development

Seedlings can reach a height of 15 cm in the first year. Bole diameter increments vary strongly between individual trees. In a survey in a semi-deciduous forest in Côte d’Ivoire, annual diameter growth rates of trees with a bole diameter of 6.5–20 cm were 0.5–1 cm, diminishing to about 0.3 cm for trees with a bole diameter of 25 cm. Extreme annual growth rates measured over the survey period were 1.5 cm for a tree with an initial bole diameter of 8.5 cm, and 2 cm for a tree with an initial bole diameter of 45 cm.
Celtis zenkeri is a common constituent of the upper canopy, which tolerates shade at initial stages of its growth. The tree is deciduous and begins to shed it leaves from November in Ghana, and leafless trees are common in February. Flushes of new, pale green leaves usually appear before all old leaves are shed. Flowering of trees is difficult to notice; it has been recorded in Ghana in March and August–September, whereas fruits mature in March–May and in November. In Nigeria flowering is reported in February–April and fruiting in March–May. In Uganda, fruits have been observed on trees with a bole diameter of 40 cm; fruits were present during more than 10 months. The fruits are eaten by birds and primates, which disperse the fruit stones.

Ecology

Celtis zenkeri characteristically occurs in semi-deciduous and deciduous forest, often in drier localities, up to 1800 m altitude. It is also found in savanna woodland, fringing forest and drier forest remnants. Celtis zenkeri prefers soils with pH above 6, and does not grow well on acid soils and in swampy conditions.

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Propagation and planting

Celtis zenkeri can be propagated by seed, but the germination rate is low. Seeds start germinating after 2–4 weeks.

Diseases and pests

Lasiodiplodia theobromae (‘diplodia pod rot of cocoa’) also affects Celtis zenkeri.

Harvesting

The minimum bole diameter allowed for felling in Ghana and the Central African Republic is 70 cm, and 50 cm in Cameroon. The length of the merchantable bole is rarely more than 15 m. Tension wood is present in some logs.

Handling after harvest

Logs should be extracted quickly from the forest or treated with preservatives because they are prone to blue stain and insect attacks. They float in water and can be transported by river.

Genetic resources and breeding

Celtis zenkeri is widespread and locally common, and does not appear to be liable to genetic erosion.

Prospects

Although Celtis zenkeri does not have much economic importance on the international markets, its wood has a high value for local markets, and it is also appreciated as a medicinal plant. Although its relatively low durability is a disadvantage, the timber may gain importance in the international market because it can be used for a variety of applications. Although current demand is low, production could be increased substantially since the species is abundant and is widely distributed. It is considered of potential economic importance in both Uganda and Ghana.

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, 2009. Celtis d’Afrique. [Internet] Tropix 6.0. http://tropix.cirad.fr/ africa/ celtis.pdf. Accessed January 2012.
• Irvine, F.R., 1961. Woody plants of Ghana, with special reference to their uses. Oxford University Press, London, United Kingdom. 868 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.
• Letouzey, R., 1968. Ulmaceae. Flore du Cameroun. Volume 8. Muséum National d’Histoire Naturelle, Paris, France. pp. 3–65.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
• Ofori, J., Brentuo, B., Mensah, M., Mohammed, A.I. & Boamah-Tawiah, R., 2009. Properties of 10 Ghanaian high density lesser-used-species of importance to bridge construction. Part 1: green moisture content, basic density and shrinkage characteristics. Ghana Journal of Forestry 25: 67–77.
• Ofori, J., Mohammed, A.I., Brentuo, B., Mensah, M. & Boamah-Tawiah, R., 2009. Properties of 10 Ghanaian high density lesser-used-species of importance to bridge construction. Part 2: mechanical strength properties. Ghana Journal of Forestry 25: 78–92.
• Polhill, R.M., 1966. Ulmaceae. In: Hubbard, O.B.E. & Milne-Redhead, E. (Editors). Flora of Tropical East Africa. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. 15 pp.

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Other references

• 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.
• ATIBT (Association Technique Internationale des Bois Tropicaux), 1986. Tropical timber atlas: Part 1 – Africa. ATIBT, Paris, France. 208 pp.
• Aubréville, A., 1959. La flore forestière de la Côte d’Ivoire. Deuxième édition révisée. Tome premier. Publication No 15. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 369 pp.
• Babweteera, F. & Brown, N., 2010. Spatial patterns of tree recruitment in East African tropical forests that have lost their vertebrate seed dispersers. Journal of Tropical Ecology 26: 193–203.
• 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.
• de Saint-Aubin, G., 1963. La forêt du Gabon. Publication No 21 du Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 208 pp.
• Devineau, J.-L., 1991. Variabilité de la croissance en circonférence dans les forêts semi-décidues de Lamto (Côte d’Ivoire). Revue d’Ecologie: La Terre et la Vie 46(2) : 95–123.
• 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.
• 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.
• Ocloo, J.K. & Laing, E., 2003. Correlation of relative density and strength properties with anatomical properties of the wood of Ghanaian Celtis species. Discovery and Innovation 15(3–4): 186–196.
• Oteng-Amoako, A.A. (Editor), 2006. 100 tropical African timber trees from Ghana: tree description and wood identification with notes on distribution, ecology, silviculture, ethnobotany and wood uses. 304 pp.
• Sallenave, P., 1955. Propriétés physiques et mécaniques des bois tropicaux de l’Union française. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 129 pp.
• Sattarian, A., 2006. Contribution to the biosystematics of Celtis L. (Celtidaceae) with special emphasis on the African species. PhD thesis. Wageningen University, Wageningen, Netherlands. 142 pp.
• Savill, P.S. & Fox, J.E.D., 1967. Trees of Sierra Leone. Forest Department, Freetown, Sierra Leone. 316 pp.
• Songwe, N.C., Okali, D.U.U. & Fasehun, F.E., 1995. Litter decomposition and nutrient release in a tropical rainforest, Southern Bakundu Forest Reserve, Cameroon. Journal of Tropical Ecology 11(3): 333–350.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan. 248 pp.
• Taylor, C.J., 1960. Synecology and silviculture in Ghana. Thomas Nelson and Sons, Edinburgh, United Kingdom. 418 pp.
• Vivien, J. & Faure, J.J., 1985. Arbres des forêts denses d’Afrique Centrale. Agence de Coopération Culturelle et Technique, Paris, France. 565 pp.
• White, L. & Abernethy, K., 1997. A guide to the vegetation of the Lopé Reserve, Gabon. 2nd edition. Wildlife Conservation Society, New York, United States. 224 pp.

Afriref references

Sources of illustration

• Letouzey, R., 1968. Ulmaceae. Flore du Cameroun. Volume 8. Muséum National d’Histoire Naturelle, Paris, France. pp. 3–65.
• 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. Essien Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
•	A.A. Oteng-Amoako 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

Essien, C. & Oteng-Amoako, A.A., 2012. Celtis zenkeri Engl. [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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