Prota 7(2): Timbers/Bois d’œuvre 2
Bot. Jahrb. Syst. 38: 77, fig. 2 (1905).
Caesalpiniaceae (Leguminosae - Caesalpinioideae)
2n = 24
Origin and geographic distribution
Stemonocoleus micranthus occurs from Côte d’Ivoire east to the Central African Republic and south to Gabon and Congo.
The wood is suitable for light construction, flooring, joinery, interior trim, ship building, handles, ladders, sporting goods, toys, novelties, agricultural implements, boxes, crates, turnery, veneer, plywood, hardboard, particle board and pulpwood.
In the Central African Republic the bark is pounded in water and applied as a paste to treat rheumatism and infertility in women.
The heartwood is purplish pink, changing to reddish brown upon exposure, and distinctly demarcated from the pale yellow sapwood. The grain is straight, texture moderately fine.
The wood is moderately heavy, with a density of about 660 kg/m³ at 12% moisture content. It air dries fairly rapidly, but may develop end checks and heart shakes. The rates of shrinkage are moderate, from green to oven dry 3.5% radial and 5.2% tangential. At 12% moisture content, the modulus of rupture is 134 N/mm², modulus of elasticity 11,950 N/mm², compression parallel to grain 57 N/mm², shear 9 N/mm², cleavage 20.5 N/mm and Chalais-Meudon side hardness 2.6.
The wood saws and works well but slowly because it is tough and moderately hard. It can be planed to a nice and lustrous surface. The wood is only moderately durable, being susceptible to termite, Lyctus and marine borer attacks.
Medium-sized to large tree up to 45(–50) m tall; bole straight and cylindrical, branchless for up to 25 m, up to 150 cm in diameter, with thick buttresses up to 6 m high or fluted at base; bark surface fairly smooth in younger trees to longitudinally fissured in old trees, greyish brown, inner bark fibrous, pale brown to pinkish; twigs glabrous. Leaves alternate, imparipinnately compound with 4–10 leaflets; stipules minute or absent; petiole and rachis together 5–17 cm long; petiolules 5–7 mm long, often twisted; leaflets alternate, elliptical to ovate, 4–11 cm × 2–5 cm, cuneate to obtuse and often slightly asymmetrical at base, usually notched at apex, with thickened margin, papery, glabrous, with indistinct translucent glandular dots, pinnately veined with 6–10 pairs of lateral veins. Inflorescence an axillary or terminal panicle up to 12 cm long, consisting of racemes up to 5 cm long, with conspicuous scars of fallen flowers, glabrous. Flowers bisexual, regular, fragrant, sessile, with 1 bract and 2 bracteoles at base; calyx with 4 oblong to obovate lobes 2–3 mm long, greenish white; petals absent; stamens 4, fused at base; ovary superior, elongate, glabrous, stiped, 1-celled, style curved. Fruit an elliptical, papery pod 11–14 cm × 4–5 cm, yellow to pale brown, reticulately veined, often twisted at base and with slender, up to 2 cm long stipe, indehiscent, 1–2-seeded. Seeds elliptical, flattened, 1.5–2 cm long. Seedling with epigeal germination; hypocotyl 2–4.5 cm long, epicotyl 4–7 cm long; cotyledons slightly fleshy, broadly ovate, 1–2 cm long; first 2 leaves opposite, with 1–6 leaflets.
In West Africa trees can be found flowering from August to March. The papery fruits ripen about 3 months later and are dispersed by wind.
Stemonocoleus comprises a single species and belongs to the tribe Detarieae; it seems to be most closely related to Augouardia, which is endemic to Gabon.
Stemonocoleus micranthus occurs in lowland moist evergreen forest, often near rivers.
In general Stemonocoleus micranthus is uncommon in the forest, although in some regions it has been recorded as common, e.g. in south-western Cameroon. Locally in Côte d’Ivoire, natural regeneration has been recorded as common, with many seedlings close to parent trees, often in more open sites, e.g. along roadsides. Stemonocoleus micranthus is characterized as a non-pioneer light demander.
Genetic resources and breeding
Stemonocoleus micranthus is widespread and does not seem to be threatened by genetic erosion. However, it occurs scattered and is in many regions even rare, and some monitoring of populations is advisable.
Stemonocoleus micranthus produces an interesting multipurpose timber and the tree becomes big enough to be of commercial interest, although the bole of old trees often becomes fluted in the lower part. The species is poorly known because in most regions it occurs too scattered or is even rare. Research is needed on propagation and growth rates to determine its possibilities for sustainable exploitation in managed natural forest.
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Correct citation of this article:
Lemmens, R.H.M.J., 2010. Stemonocoleus micranthus Harms. In: Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (Editors). Prota 7(2): Timbers/Bois d’œuvre 2. [CD-Rom]. PROTA, Wageningen, Netherlands.