Prota 14: Vegetable oils/Oléagineux
Bull. Herb. Boissier, sér. 2, 1: 20 (1900).
Mimosaceae (Leguminosae - Mimosoideae)
Origin and geographic distribution
Pentaclethra eetveldeana occurs in Cameroon, Equatorial Guinea, Gabon, Congo, DR Congo and Cabinda (Angola).
An edible oil can be extracted from the seeds of Pentaclethra eetveldeana; this oil has similar qualities to that of Pentaclethra macrophylla Benth. The seeds are eaten in DR Congo. The wood is used for construction and implements (e.g. pestles and mortars). It is also suitable for flooring, interior trim, joinery, furniture, cabinet work, toys and novelties, mine props, vehicle bodies, railway sleepers, turnery, veneer, plywood, hardboard and particle board. The wood is commonly used as firewood and for charcoal production. In DR Congo a leaf decoction is taken to treat stomach-ache and colds, and the root bark is used to treat malaria, epilepsy and haemorrhoids. In Congo a bark decoction is administered to treat respiratory troubles, tuberculosis, genito-urinary complaints and as an anthelmintic; it is applied externally against rheumatism and as an anodyne. Bark sap is administered as eye drops to treat filariasis. The foliage serves as food for edible caterpillars, and honey bees collect nectar from the flowers.
Production and international trade
Pentaclethra eetveldeana timber is exported in small amounts from Congo and DR Congo, but statistics are not available.
The composition of the seed oil has not been documented, but is probably similar to that of Pentaclethra macrophylla. The heartwood is pinkish white or yellowish white to dark brown, and distinctly demarcated from the up to 2.5 cm thick white to pale yellow sapwood. The grain is straight, texture medium to coarse. Dark-coloured veins may be visible on the radial surface of the wood, whereas the tangential surface is slightly striped. The wood is moderately heavy, with a density of about 750 kg/m3 at 12% moisture content. It air dries fairly well, but shrinkage is considerable and it is liable to checking. Although the wood is fairly hard, sawing does not cause great difficulties as long as speeds are slow. The wood finishes satisfactorily. It does not split in nailing and holds nails well. The wood is moderately durable, being susceptible to pinhole borer and marine borer attacks and moderately resistant to termites. The heartwood is resistant to impregnation by preservatives, the sapwood permeable.
Bark extracts of Pentaclethra eetveldeana showed antifungal activity. Some monoglycerides and fatty acid conjugates of triterpenes were isolated from the root bark.
In Gabon the honey produced by bees from Pentaclethra eetveldeana nectar is reportedly toxic, causing nausea and colic, but this is not the case in DR Congo.
Medium-sized tree up to 30 m tall; bole often sinuous, up to 50 cm in diameter, with small buttresses at base or without buttresses; outer bark grey, fissured, inner bark brown; crown dome-shaped; young twigs brown pubescent. Leaves alternate, bipinnately compound, up to 40 cm long; stipules linear-lanceolate, caducous; petiole 4.5–7 cm long, swollen and jointed at base, channeled; pinnae opposite, in 9–16 pairs, 4–12 cm long, at base markedly jointed, with 15–30 pairs of leaflets; leaflets opposite, sessile, obliquely rhomboid, 8–13 mm × 2–3.5 mm, apex acute, glabrous. Inflorescence a terminal or axillary panicle up to 30 cm long, consisting of spikes, many-flowered; peduncle 1.5–2 cm long, pubescent. Flowers bisexual, regular, 5-merous, small, fragrant, sessile; calyx campanulate, 1.5–2 mm long, with broadly triangular lobes c. 0.5 mm long; petals oblong-lanceolate, c. 4 mm long, basally swollen and fused for 1–2 mm, whitish; stamens 5, c. 5 mm long, anthers with large gland between the thecae, staminodes 5, filiform, c. 9 mm long; ovary superior, shortly stiped, 1-celled, densely hairy, style c. 4 mm long, stigma club-shaped. Fruit an obliquely ellipsoid-oblong pod up to 20 cm × 4 cm, woody, reddish brown, longitudinally striped, tapering to the base, apex obtuse, long-persistent and opening explosively on the tree and then recurving strongly, 3–8-seeded. Seeds orbicular to ovoid, flattened, 2–3 cm × 2–2.5 cm, smooth, reddish brown.
The roots of Pentaclethra eetveldeana produce nodules containing nitrogen-fixing bacteria. The base of the bole is often severely deformed by elephant feeding. The flowers produce large amounts of nectar and attract primates (e.g. chimpanzees), birds and insects. The woody pods are held erect above the canopy and open explosively when ripe. However, some monkeys are able to break through the tough wall of the pod and eat the unripe seeds.
Pentaclethra comprises 3 species, 2 in Africa and 1 in South America. The other African species, Pentaclethra macrophylla Benth., can be distinguished by its larger leaflets and stellate hairs.
Pentaclethra eetveldeana occurs in rainforest, most commonly in secondary forest, where it may be dominant. It can also be found in pockets of forest in savanna regions and in gallery forest.
The germination rate of seeds is generally high, but germination is often unevenly distributed. It is recommended that the seeds be planted directly into the field because the taproot of the seedlings is easily damaged in transplanting. Planted trees can be managed by coppicing.
Genetic resources and breeding
As it is most common in secondary and disturbed forest, Pentaclethra eetveldeana is not endangered by genetic erosion.
Pentaclethra eetveldeana might be an interesting timber tree for sustainably managed natural forest in Central Africa because of its easy regeneration after disturbance of the forest and its fair wood properties, but its often small-sized and irregular bole is a drawback.
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Correct citation of this article:
Lemmens, R.H.M.J., 2007. Pentaclethra eetveldeana De Wild. & T.Durand In: van der Vossen, H.A.M. & Mkamilo, G.S. (Editors). PROTA 14: Vegetable oils/Oléagineux. [CD-Rom]. PROTA, Wageningen, Netherlands.
leaves and inflorescences