Uapaca heudelotii

Family

Euphorbiaceae (APG: Phyllanthaceae)

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Chromosome number

2n = 26

Synonyms

Vernacular names

Rikio des rivières (Fr).

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Origin and geographic distribution

Uapaca heudelotii occurs from Guinea east to the Central African Republic and DR Congo, and south to northern Angola.

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Uses

The wood is used for construction, joinery and planks. It is suitable for flooring, interior trim, mine props, ship building, vehicle bodies, furniture and railway sleepers. The stilt roots and branches are suitable for boat ribs. The wood produces good firewood and charcoal.
The fruits are edible; they are quite sweet and locally appreciated. The roots and bark are used in traditional medicine for similar purposes as those of Uapaca guineensis Müll.Arg. Root preparations are taken as expectorant, and to treat fever and headache. Bark decoctions are administered to treat dysentery, food poisoning, female sterility, ovarian disorders, toothache, rheumatism, oedema and haemorrhoids. They are also applied as enema to treat constipation, and rubbed in against swellings. Pulped leaves with palm oil are applied to furuncles to mature them and to relieve migraine and rheumatism. The bark has been used to dye fishing lines. The tree with its stilt roots prevents erosion on stream banks and promotes accumulation of silt.

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Properties

The heartwood is pale red to reddish brown, often with darker streaks, and not distinctly demarcated from the sapwood. The grain is usually straight, texture moderately coarse. The wood is medium-weight, with a density of 680–790 kg/m³ at 12% moisture content. It air dries fairly rapidly, but should be dried with some care because it has some tendency to warp and develop surface checking. The rates of shrinkage are rather high, from green to oven dry 4.6% radial and 9.8% tangential. Once dry, the wood is quite unstable in service.
At 12% moisture content, the modulus of rupture is (100–)132–166 N/mm², modulus of elasticity 11,560 N/mm², compression parallel to grain 56–63 N/mm², cleavage 21–23 N/mm and Chalais-Meudon side hardness 2.9–5.5.
The wood is rather difficult to saw and work, particularly dried wood; it contains silica. It is recommended to use stellite-tipped saw teeth and tungsten-carbide tipped cutting edges. The wood finishes well and glues satisfactorily. It is moderately durable, being quite resistant to fungi and dry-wood borers, and moderately resistant to termites and marine borers. The heartwood is resistant to impregnation with preservatives.
Several alkaloids have been found in the leaves.

Description

Evergreen, dioecious, small to medium-sized tree up to 20(–30) m tall; bole branchless for up to 8 m, usually straight and cylindrical, up to 100 cm in diameter, on stilt roots up to 3 m high; bark surface scaly, grey-brown, inner bark pinkish to pale reddish brown, with red exudate; crown rather dense, much-branched; twigs with tufts of reddish hairs in leaf axils, with conspicuous leaf scars. Leaves arranged spirally, crowded towards the end of the branches, simple and entire; stipules absent; petiole 0.5–3.5(–5.5) cm long; blade elliptical to obovate, (6–)10–15(–25) cm × 2.5–5(–8) cm, base cuneate, apex obtuse to rounded or indistinctly short-acuminate, papery, glabrous, pinnately veined with (8–)10–13(–17) pairs of lateral veins. Male inflorescence an axillary globose head 7–8 mm in diameter, on a peduncle up to 2 cm long, with c. 10 yellowish bracts up to 1 cm long; female flowers solitary. Flowers unisexual, 4–5-merous; male flowers sessile, with unequal calyx lobes up to 2 mm long, petals c. 1 mm long or absent, stamens free, 2.5–4 mm long, rudimentary ovary up to 1.5 mm long, glabrous; female flowers pedicelled, calyx shallowly cup-shaped with triangular to rounded lobes up to 1 mm long, glabrous, ovary superior, ellipsoid, 5–6 mm long, 3-celled, glabrous, styles 3. Fruit an ellipsoid to obovoid drupe 2–3 cm long, slightly angular, smooth but often with some small warts, glabrous, with 3 stones, each stone 1-seeded. Seedling with epigeal germination; hypocotyl 3–4 cm long, channeled, epicotyl c. 3 cm long; cotyledons rounded, c. 2.5 cm wide; first leaves alternate.

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Other botanical information

Uapaca comprises about 50 species from tropical Africa and Madagascar, and is in need of a complete revision.
Uapaca acuminata (Hutch.) Pax & K.Hoffm. is a medium-sized to fairly large tree up to 35 m tall with bole up to 80 cm in diameter, supported by stilt roots up to 4 m high. It occurs from southern Nigeria to western DR Congo. It has been considered as a variety of Uapaca heudelotii (var. acuminata Hutch.) and its wood, bark and fruits are undoubtedly used for similar purposes. In the literature the two species have been confused. Uapaca acuminata differs from Uapaca heudelotii in its glabrous twigs, usually smaller and more distinctly short-acuminate leaves, and in its ecology, preferring well-drained localities in primary and secondary forest.

Anatomy

Wood-anatomical description (IAWA hardwood codes):
Growth rings: 2: growth ring boundaries indistinct or absent. Vessels: 5: wood diffuse-porous; (12: solitary vessel outline angular); 13: simple perforation plates; 22: intervessel pits alternate; (23: shape of alternate pits polygonal); 26: intervessel pits medium (7–10 μm); 27: intervessel pits large (≥ 10 μm); 31: vessel-ray pits with much reduced borders to apparently simple: pits rounded or angular; 32: vessel-ray pits with much reduced borders to apparently simple: pits horizontal (scalariform, gash-like) to vertical (palisade); 42: mean tangential diameter of vessel lumina 100–200 μm; 47: 5–20 vessels per square millimetre. Tracheids and fibres: 61: fibres with simple to minutely bordered pits; 66: non-septate fibres present; 69: fibres thin- to thick-walled. Axial parenchyma: 76: axial parenchyma diffuse; 78: axial parenchyma scanty paratracheal; 79: axial parenchyma vasicentric; 93: eight (5–8) cells per parenchyma strand. Rays: (97: ray width 1–3 cells); 98: larger rays commonly 4- to 10-seriate; 102: ray height > 1 mm; 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; (109: rays with procumbent, square and upright cells mixed throughout the ray); 113: disjunctive ray parenchyma cell walls present; 115: 4–12 rays per mm. Mineral inclusions: 159: silica bodies present; 160: silica bodies in ray cells; (161: silica bodies in axial parenchyma cells).
(P. Mugabi, P.E. Gasson & E.A. Wheeler)

Growth and development

In Côte d’Ivoire trees flower in December–January, in Nigeria in December–February, and in Gabon at the beginning of the rainy season when the water level of the rivers rises. In Côte d’Ivoire fruits have been found in May–June and September–October. They are eaten by birds such as turacos and parrots, and by fruit bats, monkeys, chimpanzees, gorillas, duikers, pigs, civets and elephants, which all may disperse the seeds. Trees grow in symbiosis with ectomycorrhizal fungi.

Ecology

Uapaca heudelotii is characteristic for riverine forest, in forested as well as savanna regions, up to 500 m altitude. It is always close to the water, or the stilt roots are in the water resembling mangrove vegetation and providing shelter and breeding ground for river fishes. It is locally common in seasonally flooded areas.

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Propagation and planting

There are about 2500 seeds per kg. Seeds usually start germinating 2–3 weeks after sowing, and the germination rate is high.

Management

The preference for river banks makes that felling the trees and removing the logs are often difficult operations, and the stilt roots cause additional difficulties during exploitation.

Genetic resources and breeding

There are no signs that Uapaca heudelotii is threatened by genetic erosion.

Prospects

The wood is mainly used locally and this situation will probably not change because difficulties in processing the timber limit the possibilities for export. The presence of stilt roots and the preference of Uapaca heudelotii for water habitats make harvesting difficult. Uapaca heudelotii may be well suited for planting to restore riverine forest and to stabilize river banks.

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.
• Breteler, F.J., 2012. Novitates Gabonensis 71. A new species of Uapaca (Phyllanthaceae, formerly Euphorbiaceae) from Gabon. Plant Ecology and Evolution 145(1): 129–131.
• Burkill, H.M., 1994. The useful plants of West Tropical Africa. 2nd Edition. Volume 2, Families E–I. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 636 pp.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan. 248 pp.
• Vivien, J. & Faure, J.J., 1996. Fruitiers sauvages d’Afrique: espèces du Cameroun. Ministère Français de la Coopération, Paris, France & CTA, Wageningen, Netherlands. 416 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.
• Aubréville, A., 1959. La flore forestière de la Côte d’Ivoire. Deuxième édition révisée. Tome deuxième. Publication No 15. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 341 pp.
• Barku, V.A., 1996. Chemical constituents of the leaves of Uapaca heudelotii Baill. B.Sc. Chemistry degree thesis, Department of Chemistry, Faculty of Science, University of Cape Coast, Ghana. 33 pp.
• Cooper, G.P. & Record, S.J., 1931. The evergreen forests of Liberia. School of Forestry, Yale University, Bulletin 31, New Haven, United States. 153 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.
• 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.
• 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.
• 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.
• Pauwels, L., 1993. Nzayilu N’ti: guide des arbres et arbustes de la région de Kinshasa Brazzaville. Scripta Botanica Belgica. Volume 4. Jardin botanique national de Belgique, Meise, Belgium. 495 pp.
• Raponda-Walker, A. & Sillans, R., 1961. Les plantes utiles du Gabon. Paul Lechevalier, Paris, France. 614 pp.
• Tailfer, Y., 1989. La forêt dense d’Afrique centrale. Identification pratique des principaux arbres. Tome 2. CTA, Wageningen, Pays-Bas. pp. 465–1271.
• Voorhoeve, A.G., 1979. Liberian high forest trees. A systematic botanical study of the 75 most important or frequent high forest trees, with reference to numerous related species. Agricultural Research Reports 652, 2nd Impression. Centre for Agricultural Publishing and Documentation, Wageningen, Netherlands. 416 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.

Sources of illustration

• 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.

Author(s)

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

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

Lemmens, R.H.M.J., 2012. Uapaca heudelotii Baill. [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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