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Uapaca guineensis Müll.Arg.

Protologue
Flora 47: 517 (1864).
Family
Euphorbiaceae (APG: Phyllanthaceae)
Chromosome number
2n = 26
Vernacular names
Sugar plum, red cedar, false mahogany, rikio (En). Palétuvier de rivière, palétuvier d’eau douce (Fr). Sambi, cor de mogno (Po).
Origin and geographic distribution
Uapaca guineensis occurs from Senegal east to the Central African Republic and south to DR Congo and Tanzania. It probably also occurs in Uganda.
Uses
Especially the roots of Uapaca guineensis are widely used medicinally; stem bark, leaves and fruits are used to a lesser extent. Root preparations are commonly taken as an aphrodisiac and to treat male impotence. In Sierra Leone a steam bath with the roots is used to treat headache. In Côte d’Ivoire a root bark preparation is applied to leprous sores and taken as a tonic by women who have just given birth. In Côte d’Ivoire and Congo a root bark decoction is taken orally or as an enema to treat oedema and gastro-intestinal problems. In Gabon a root bark decoction is applied in the form of an enema as an emetic; a stem bark extract is drunk for the same purpose. Powdered root bark is sniffed to treat nasal cancer. In Congo and DR Congo a root bark decoction is taken to treat female sterility, toothache, rheumatism and piles. In Congo a root infusion is taken to treat headache caused by fever. Painful parts are embrocated with the crushed roots to ease the pain. A root infusion is taken with sugar cane juice to treat a blocked nose and pulmonary afflictions. In Gabon stem bark scrapings mixed with salt are rubbed in to treat skin complaints. In DR Congo a decoction of leaves, stem bark or root bark is taken to treat dysentery, diarrhoea, stomach-ache and venereal diseases. Pulped leaves with palm oil are applied to furuncles to mature them and to relieve migraine and rheumatism. They are also massaged onto legs of rachitic children to strengthen them. In Tanzania a stem bark decoction is taken to treat malaria. In Liberia unripe fruits are taken as a cough medicine. In northern Nigeria the flowers and bark enter into arrow poison preparations.
The fruits have a sweetish edible pulp which can be eaten raw. Its taste resembles that of dried prunes or avocado. In Nigeria the pulp is made into a refreshing drink. The wood is used locally in carpentry and to make planks, railway sleepers, beams, furniture, beds and kitchen utensils. Throughout West Africa the bole is used to make dugout canoes. The stilt roots and branches are suitable for boat ribs. The wood produces good firewood and charcoal. Young twigs exude a red sticky sap, which dries like a gum and is used as a dye, e.g. for fishing lines. In Nigeria the large leaves are used to wrap kola nuts. The tree is used for shade and could be planted in coffee and cocoa plantations. It can also be planted to stabilize river banks.
Production and international trade
In Liberia, Cameroon and DR Congo Uapaca guineensis is commercially exploited under its trade name ‘rikio’, but nowadays only at a local level. In Liberia the wood has been exported in the past as ‘false mahogany’.
Properties
An ethanol extract of the wood showed moderate antiplasmodial activity in vitro. An ethanolic root bark extract and an ethanolic stem bark extract did not show significant antibacterial or antifungal activity against human pathogens in vitro. The wood and bark contain much tannin. The sapwood is whitish tinged red, and the heartwood red to reddish brown. The wood is hard, durable and moderately heavy, and when quarter-sawn it has an attractive silver grain. It is easy to work.
Description
Dioecious, small to medium-sized, much-branched, evergreen tree up to 18(–30) m tall; bole fluted, up to 100 cm in diameter, often on rounded stilt roots up to 3 m high; bark dark brown to blackish, cracked or scaly; crown dense and low branching; branches long, slender, almost glabrous, hollow when dry, leaf scars conspicuous; terminal bud sticky. Leaves alternate, crowded towards the end of the branches, simple; stipules linear, c. 0.5 mm long, soon falling; petiole 1.5–4(–7) cm long, jointed at top; blade broadly obovate, (5–)9–24 cm × (2–)4–10(–17) cm, base cuneate, apex rounded, margins usually wavy, papery, with numerous minute glandular raised dots, pinnately veined with 5–13 pairs of lateral veins. Male inflorescence an axillary globular to ovoid head 4–7 mm in diameter, female flowers solitary; peduncle of male inflorescence 1–1.5 cm long, with 2–4 small dispersed bracts; involucral bracts 8–10, elliptical to rounded, 1–1.5 cm long, bright yellow, enclosing the flowers in bud. Flowers unisexual, petals absent; male flowers sessile, with c. 9 unequal calyx lobes, c. 5 lobes oblong, c. 1 mm long, the others linear, small, stamens 5, filaments up to 1.5 mm long, rudimentary ovary c. 1 mm long, short-hairy; female flowers with 8–15 mm long pedicel, 6 unequal calyx lobes, triangular to rounded, 1–1.5 mm long, short-hairy, ovary superior, globose, 2.5–3 mm in diameter, 3-celled, smooth, styles 3, 4–5 mm long, reflexed, twice bifid towards apex. Fruit an almost globose drupe 2–2.5 cm in diameter, warty, glabrous, greenish, with 3 stones, usually 1 seed per stone.
Other botanical information
Uapaca comprises 50–60 species from tropical Africa and Madagascar, and is in need of a complete revision. Many Uapaca spp. are similarly used as medicinal plants. The distribution area of Uapaca guineensis is not easy to establish as several Uapaca species are very similar. The presence of Uapaca guineensis in the drier parts of West Africa is doubtful and local specimens possibly belong to Uapaca togoensis Pax. In older floras the distribution area of Uapaca guineensis extended to southern Africa, but nowadays the plants from southern Africa are considered to belong to a separate species, Uapaca lissopyrena Radcl.-Sm.
Anatomy
Wood-anatomical description (IAWA hardwood codes):
Growth rings: 2: growth ring boundaries indistinct or absent. Vessels: 5: wood diffuse-porous; 13: simple perforation plates; (14: scalariform perforation plates); (15: scalariform perforation plates with 10 bars); 22: intervessel pits alternate; 23: shape of alternate pits polygonal; 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; 43: mean tangential diameter of vessel lumina 200 μm; (46: 5 vessels per square millimetre); 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: 76: axial parenchyma diffuse; 77: axial parenchyma diffuse-in-aggregates; 78: axial parenchyma scanty paratracheal; (79: axial parenchyma vasicentric); 92: four (3–4) cells per parenchyma strand; 93: eight (5–8) cells per parenchyma strand; 94: over eight cells per parenchyma strand. Rays: 98: larger rays commonly 4- to 10-seriate; 102: ray height > 1 mm; (103: rays of two distinct sizes); 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); 115: 4–12 rays per mm. Mineral inclusions: 159: silica bodies present; 160: silica bodies in ray cells.
(D. Louppe, P. Détienne & E.A. Wheeler)
Growth and development
In southern Cameroon seedlings of Uapaca guineensis are found to be fast growing, both in shade or in full sun, and even in relatively dry localities. They may become 4–5 m tall in 6 years. The fruits of Uapaca guineensis are eaten by fruit bats, monkeys, chimpanzees and gorillas, which may disperse the seeds. The tree grows in symbiosis with several ectomycorrhizal fungi.
Ecology
Uapaca guineensis occurs in humid localities in rainforest and is common along river banks, where it sometimes forms pure stands. It also occurs in mixed evergreen forest and forest margins, in bushland on steep slopes, from sea-level up to 1100 m altitude.
Propagation and planting
Multiplication of Uapaca guineensis is by seed or wildlings. In Tanzania fruits can be collected throughout the year with a peak in November–December. The seeds must be sown when still fresh, as they do not store well. The germination rate is up to 80%. In DR Congo seed set and germination are often poor.
Management
Uapaca guineensis can be coppiced and pollarded. It has been planted as a forest regeneration tree in Guinea, to provide a green corridor for large forest animals. In Burundi it has been planted in an arboretum as an experiment to stabilize river banks.
Diseases and pests
No diseases are known on Uapaca guineensis, but several insects feed on the leaves and buds, especially beetles (Anthribidae, Chrysomelidae and Scolytidae), whereas other beetles such as Xylosandrus crassiusculus feed on the wood.
Harvesting
All plant parts can be harvested whenever the need arises. The root bark can be easily harvested from the stilt roots.
Genetic resources
Although Uapaca guineensis is much exploited for its wood, it is also widespread and locally common and there are no signs that it is threatened by genetic erosion.
Prospects
Uapaca guineensis is commonly used as a medicinal plant against a variety of diseases. No phytochemical analyses have been effected, and only few pharmacological tests have been done. Additional research is recommended so that the active compounds can be identified and the potential of these compounds can be evaluated. It is also recommended to plant Uapaca guineensis along rivers with a large difference in water flow to stabilize the banks.
Major references
• 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.
• Carter, S. & Radcliffe-Smith, A., 1988. Euphorbiaceae (part 2). In: Polhill, R.M. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. pp. 409–597.
• Lubini, A. & Mandango, A., 1981. Etude phytosociologique et écologique des forets à Uapaca guineensis dans le nord-est du district forestier central (Zaïre). Bulletin du Jardin Botanique National de Belgique 51(3–4): 231–254.
• Marshall, S.J., Russell, P.F., Phillipson, J.D., Kirby, G.C., Warhurst, D.C. & Wright, C.W., 2000. Antiplasmodial and antiamoebic activities of medicinal plants from Sierra Leone. Phytotherapy Research 14: 356–358.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
• Ruffo, C.K., Birnie, A. & Tengnäs, B., 2002. Edible wild plants of Tanzania. Technical Handbook No 27. Regional Land Management Unit/ SIDA, Nairobi, Kenya. 766 pp.
• 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.
Other references
• Atindehou, K.K., Koné, M., Terreaux, C., Traoré, D., Hostettmann, K. & Dosso, M., 2002. Evaluation of the antimicrobial potential of medicinal plants from the Ivory Coast. Phytotherapy Research 16(5): 497–502.
• Betti, J.L., 2004. An ethnobotanical study of medicinal plants among the Baka pygmies in the Dja biosphere reserve, Cameroon. African Study Monographs 25(1): 1–27.
• Eyog Matig, O., Ndoye, O., Kengue, J. & Awono, A. (Editors), 2006. Les fruitiers forestiers comestibles du Cameroun. IPGRI Regional Office for West and Central Africa, Cotonou, Benin. 204 pp.
• Gassita, J.N., Nze Ekekang, L., De Vecchy, H., Louis, A.M., Koudogbo, B. & Ekomié, R. (Editors), 1982. Les plantes médicinales du Gabon. CENAREST, IPHAMETRA, mission ethnobotanique de l’ACCT au Gabon, 10–31 juillet 1982. 26 pp.
• InsideWood, undated. [Internet] http://insidewood.lib.ncsu.edu/search/. Accessed May 2007.
• 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.
• Stäuble, N., 1986. Etude ethnobotanique des Euphorbiacées d’Afrique de l’Ouest. Journal of Ethnopharmacology 16: 23–103.
• 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.
Sources of illustration
• Wilks, C. & Issembé, Y., 2000. Les arbres de la Guinée Equatoriale: Guide pratique d’identification: région continentale. Projet CUREF, Bata, Guinée Equatoriale. 546 pp.
• 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.
Author(s)
M.M. Kitambala
Département de Chimie de la Faculté des Sciences, Université de Lubumbashi, Lubumbashi, DR Congo


Editors
G.H. Schmelzer
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
A. Gurib-Fakim
Faculty of Science, University of Mauritius, Réduit, Mauritius
Associate editors
C.H. Bosch
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
M.S.J. Simmonds
Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, United Kingdom
R. Arroo
Leicester School of Pharmacy, Natural Products Research, De Montfort University, The Gateway, Leicester LE1 9BH, United Kingdom
A. de Ruijter
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
Photo editor
A. de Ruijter
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article:
Kitambala, M.M., 2008. Uapaca guineensis Müll.Arg. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes médicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.
Distribution Map wild


1, base of bole; 2, branch with male flowers; 3, fruit; 4, stone.
Redrawn and adapted by Achmad Satiri Nurhaman



fruiting branch


wood in transverse section


wood in tangential section


wood in radial section