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Isomacrolobium explicans (Baill.) Breteler

Syst. Geogr. Pl. 78: 143 (2008).
Caesalpiniaceae (Leguminosae - Caesalpinioideae)
Macrolobium heudelotii Planch. ex Benth. (1865), Anthonotha explicans (Baill.) J.Léonard (1955), Triplisomeris explicans (Baill.) Aubrév. & Pellegr. (1958).
Origin and geographic distribution
Isomacrolobium explicans occurs in Guinea, Sierra Leone and Liberia.
In Liberia the wood is used for planks. Split twig ends are used as tying material for sheaves and in hut building. The seeds are sometimes eaten in times of food shortage.
The heartwood is dull purplish brown, often streaked; sapwood pale brown. The grain is fairly straight, texture moderately fine. The wood is heavy, hard, tough and strong. It is easy to cut, finishes smoothly and is durable.
Dried seeds contain per 100 g: water 8.0 g, energy 1523 kJ (364 kcal), protein 5.1 g, fat 7.0 g, carbohydrate 83.6 g, fibre 4.1 g, Ca 322 mg and P 119 mg.
Small to medium-sized tree up to 20(–33) m tall; bole often short and twisted, up to 60 cm in diameter, often with low buttresses; inner bark fibrous, pinkish brown; twigs glabrous to short-hairy. Leaves alternate, paripinnately compound with 2–4 pairs of leaflets; stipules ovate-triangular, 1–1.5 mm long; petiole 1–4 cm long, rachis 5–12(–20) cm long; petiolules 2–6 mm long; leaflets opposite, elliptical, (5–)8–15(–20) cm × 3–6(–9) cm, acuminate at apex, leathery, glabrous to slightly hairy below, pinnately veined with 4–8 pairs of lateral veins. Inflorescence an axillary or terminal, pendulous panicle up to 40(–70) cm long, with short raceme-like branches, short-hairy. Flowers bisexual, zygomorphic, pale yellow, fragrant, with 2 elliptical to obovate bracteoles 5–6 mm long at base; pedicel 0.5–1 cm long; sepals 4, ovate-elliptical to oblong, 5–7 mm long, glabrous, 1 slightly 2-lobed; petals 5, free, glabrous, 3 obovate and 6–8 mm × 3–5 mm, notched at apex, 2 strap-shaped to ovate-elliptical; stamens 9(–10), 3 large, 10–17 mm long, 6(–7) rudimentary and c. 1 mm long; ovary superior, 2–4 mm long, hairy, 1-celled, style glabrous. Fruit an oblong pod 13–16 cm × 5–6 cm, short-hairy, transversely veined, dehiscent with 2 thin spiralling valves, 2–3-seeded. Seeds nearly quadrangular, up to 4 cm × 3.5 cm, smooth, brown.
Isomacrolobium comprises about 12 species and is distributed in West and Central Africa. It has been united with Anthonotha in the 1950s, but recently it has been separated as a distinct genus again. Anthonotha s.s. differs from Isomacrolobium in its single well-developed, 2-lobed petal and in its leaflets being densely hairy below.
Isomacrolobium explicans occurs in semi-deciduous forest and savanna woodland up to 500 m altitude.
Genetic resources and breeding
There is no reason to consider Isomacrolobium explicans as threatened. However, the species is poorly known and its conservation status needs clarification.
Isomacrolobium explicans will remain a timber tree of minor importance because of its usually small and twisted bole.
Major references
• Breteler, F.J., 2008. Anthonotha and Isomacrolobium (Leguminosae, Caesalpinioideae): two distinct genera. Systematics and Geography of Plants 78: 137–144.
• Cooper, G.P. & Record, S.J., 1931. The evergreen forests of Liberia. School of Forestry, Yale University, Bulletin 31, New Haven, United States. 153 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.
• 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
• Aubréville, A., 1959. La flore forestière de la Côte d’Ivoire. Deuxième édition révisée. Tome premier. Publication No 15. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 369 pp.
• Burkill, H.M., 1995. The useful plants of West Tropical Africa. 2nd Edition. Volume 3, Families J–L. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 857 pp.
• Busson, F., 1965. Plantes alimentaires de l’ouest Africain: étude botanique, biologique et chimique. Leconte, Marseille, France. 568 pp.
• Leung, W.-T.W., Busson, F. & Jardin, C., 1968. Food composition table for use in Africa. FAO, Rome, Italy. 306 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.
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
D. Louppe
CIRAD, Département Environnements et Sociétés, Cirad es-dir, Campus international de Baillarguet, TA C-DIR / B (Bât. C, Bur. 113), 34398 Montpellier Cedex 5, France
A.A. Oteng-Amoako
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
Associate editors
E.A. Obeng
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Correct citation of this article:
Lemmens, R.H.M.J., 2010. Isomacrolobium explicans (Baill.) Breteler. 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.