Prota 7(1): Timbers/Bois d’œuvre 1
Nat. Pflanzenfam. 3(4): 215 (1896).
Quassia gabonensis Pierre (1896).
Origin and geographic distribution
Odyendyea gabonensis is distributed in Cameroon, Equatorial Guinea, Gabon and Congo.
The wood of Odyendyea gabonensis (trade name: onzan, onzang, mbanko) is used for making musical instruments, mallets to beat bark for house construction, spoons, and bells for hunting dogs. In general it is considered suitable for ship and boat building, furniture and cabinet work, frame moulding, light boxes and crates, interior trim, matches, toys and novelties, veneer and plywood, hardboard and particle board, wood-wool, and as pulpwood.
A flour is prepared from the seeds that is used as a condiment in sauces. Fat extracted from the seeds can be eaten raw and is also made into various medicines. A mixture of the pounded leaves with palm oil is rubbed on the head against head lice, or the head is washed with a maceration of the bark for the same purpose. A decoction of the bark is taken against stomach-ache, bronchitis and lung complaints. The ground bark mixed with palm oil is applied as a salve to treat psoriasis. The flowers attract honeybees.
The heartwood is pale yellow and lustrous; it is not demarcated from the sapwood. The grain is fairly regular, sometimes irregular, texture medium to coarse; quarter-sawn surfaces occasionally have a mottled figure. The wood is lightweight with a density of about 380 kg/m³ at 12% moisture content. Shrinkage rates are 3.4% radial and 5.7% tangential from green to oven dry. The wood seasons rapidly with little splitting. The wood is soft and brittle. At 12% moisture content, the modulus of rupture is about 55 N/mm², modulus of elasticity 5700 N/mm², compression parallel to grain 28 N/mm², shear 2.2 N/mm², cleavage 9.7 N/mm and Chalais Meudon side hardness 0.9.
Seasoned wood saws easily and planes well. Screws and nails are applied easily, with little tendency for the wood to split, but it does not hold nails well. The wood peels and slices easily, but as the logs are deeply fluted peeling is not recommended.
The wood has a low durability, being liable to fungal attack and susceptible to termites, powder-post beetles (Lyctus) and dry-wood borers. The heartwood and sapwood are fairly permeable for preservatives and can be treated using pressure methods.
The ultimate fibres are 1.1 mm long and 27 μm wide, with a lumen diameter of 19 μm and a cell wall thickness of 7 μm. The wood can be pulped satisfactorily using the kraft or sulphite processes.
Cytotoxic quassinoids have been isolated from the bark.
Medium-sized to fairly large tree up to 40 m tall; bole branchless for up to 24 m, up to 200 cm in diameter, usually straight, deeply fluted over its entire height; outer bark grey to greyish green, finely longitudinally cracked, inner bark thick, fibrous, pale yellow; crown spherical; branches thick, cylindrical, blackish. Leaves arranged spirally, imparipinnately compound with 4–6 pairs of leaflets, glabrous; stipules absent; rachis 30–50 cm long, channelled at base; petiolules c. 3 mm long, channelled; leaflets oblong, up to 12 cm × 5 cm, base cuneate or rounded, apex truncate or slightly notched, leathery, pinnately veined with c. 10 pairs of hardly visible lateral veins almost perpendicular to midrib. Inflorescence a terminal panicle shorter than the leaves, branches glabrous. Flowers unisexual or bisexual, regular, 4(–5)-merous; pedicel c. 3 mm long; calyx cupule-shaped, with short obtuse lobes; petals c. 5 mm long, glabrous outside, pubescent inside; stamens 8(–10), c. 8 mm long; ovary superior, consisting of 4 fused carpels. Fruit an obovoid drupe up to 7 cm long, grooved at one side, becoming red when ripe; pyrene with thick hard wall having a longitudinal crest, 1-seeded. Kernel thick, brown.
In Gabon Odyendyea gabonensis flowers in September. The fruits are eaten by porcupines, which reportedly makes the meat of these animals bitter.
Odyendyea comprises only 1 species.
Odyendyea gabonensis occurs mainly in rainforest, in primary as well as in secondary forest, often on sandy soil. Although it nowhere occurs abundantly, it is locally common.
To prepare flour, the seeds are boiled for 2–3 hours, placed in running water for one week to eliminate bitterness, kept in a smokehouse to dry for one month, and crushed to obtain the flour.
Genetic resources and breeding
Although Odyendyea gabonensis is not mentioned in the IUCN Red list of threatened species, it has a restricted distribution and does not occur abundantly. Therefore, the species may become endangered as a result of ongoing logging activities.
The wood of Odyendyea gabonensis is soft and not durable, and the logs are too much fluted to be useful for rotary peeling. Therefore, its importance is unlikely to increase beyond being used locally. Its applications in food and medicine deserve more attention.
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Correct citation of this article:
Brink, M., 2007. Odyendyea gabonensis (Pierre) Engl. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.
wood in transverse section
wood in tangential section