Uapaca pynaertii (PROTA)

Plant Resources of Tropical Africa Introduction

List of species

General importance
Geographic coverage World

Uapaca pynaertii De Wild.

Protologue: Etudes fl. Bas- Moyen-Congo 2(3): 274 (1908).

Family: Euphorbiaceae (APG: Phyllanthaceae)

Chromosome number: 2n = 26

Synonyms

Uapaca corbisieri De Wild. (1927), Uapaca esculenta A.Chev. ex Aubrév. & Leandri (1935).

Vernacular names

Sugar plum (En). Rikio noir, borikio (Fr).

Origin and geographic distribution

Uapaca pynaertii occurs from Sierra Leone east to the Central African Republic and DR Congo, and south to Gabon.

Uses

The wood is used for joinery, planks and canoes. It is suitable for construction, flooring, interior trim, mine props, ship building, vehicle bodies, furniture, railway sleepers and turnery. It is also used as firewood and for charcoal production.

The fruits are edible with a nice taste, and locally popular.

Properties

The heartwood is pale pink to pale red and not distinctly demarcated from the sapwood. The grain is usually straight, texture moderately coarse. The wood is lustrous. It is medium-weight, with a density of about 730 kg/m³ at 12% moisture content. It should be air dried with care to prevent distortion and warping. The rates of shrinkage are quite high, from green to oven dry 6.2% radial and 9.3% tangential. Once dry, the wood is unstable in service.

At 12% moisture content, the modulus of rupture is 146 N/mm², modulus of elasticity 12,250 N/mm², compression parallel to grain 58 N/mm², shear 8.5 N/mm², cleavage 24 N/mm and Chalais-Meudon side hardness 2.8.

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.

Description

Evergreen, dioecious, small to medium-sized tree up to 30(–40) m tall; bole branchless for up to 20 m, usually straight and cylindrical, usually on stilt roots up to 5 m high; bark surface smooth to slightly cracked, grey to dark green or nearly black, inner bark pinkish brown to reddish brown with white streaks, becoming brown upon exposure; crown layered, rather open; twigs glabrous but slightly scaly, with conspicuous leaf scars. Leaves arranged spirally, crowded towards the end of the branches, simple and entire; stipules absent; petiole (1–)2–5(–13) cm long; blade obovate, 15–25(–40) cm × 5–10(–14) cm, base cuneate, apex obtuse to rounded, leathery, glabrous, pinnately veined with 7–12 pairs of lateral veins. Male inflorescence an axillary globose head 1.5–4 cm in diameter, with c. 10 yellowish bracts up to 2.5 cm long; female flowers unknown. Flowers unisexual, 4–5-merous; male flowers sessile, with unequal calyx lobes up to 1.5 mm long, stamens free, c. 6 mm long, rudimentary ovary up to 2 mm long, short-hairy. Fruit an ovoid-globose drupe up to 5 cm long, smooth, glabrous, with (4–)5 stones, each stone 1-seeded. Seedling with epigeal germination; hypocotyl 5–7 cm long, channeled, epicotyl c. 1 cm long; cotyledons rounded, up to 5.5 cm wide; first leaves alternate.

Other botanical information

In Côte d’Ivoire, in 40 years old secondary forest grown on fallow land, trees with a bole diameter of 53 cm have been recorded. In Côte d’Ivoire trees flower in November–December and ripe fruits can be found in January–July. The fruits are eaten by birds such as turacos, and by fruit bats, monkeys, chimpanzees, gorillas and elephants, which all may disperse the seeds.

Uapaca comprises about 50 species from tropical Africa and Madagascar, and is in need of a complete revision.

Ecology

Uapaca pynaertii occurs in primary as well as secondary, evergreen forest, sometimes in riverine forest, up to 800 m altitude.

Genetic resources

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

Prospects

The wood is mainly used locally and this situation will probably not change because the stilt roots and difficulties in processing the timber limit the possibilities for export. The fruits are larger than those of other Uapaca spp., and they are reportedly delicious; possibilities for further commercialization through domestication could be investigated.

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.

• de Koning, J., 1983. La forêt de Banco. Part 2: La Flore. Mededelingen Landbouwhogeschool Wageningen 83–1. Wageningen, Netherlands. 921 pp.

• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan. 248 pp.

Other references

• 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.

• 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.

• 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.

• Sallenave, P., 1964. Propriétés physiques et mécaniques des bois tropicaux. Premier supplément. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 79 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.

• 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)

• 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. Uapaca pynaertii De Wild. 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 24 April 2026.

• See the Prota4U database.