Aucoumea klaineana Pierre (Okoumé)
Nomenclature etc. BURSERACEAE. Trade and local names: okoumé (B, D, F, NL), Gaboon, Gabun (D), angouma, okaka (G), angum , ongoumi, moukoumi, zonga (EGu). Status of protection under CITES regulations: not protected.
Tree. Geographic distribution: tropical Africa.
General. Heartwood basically brown to red to white or grey. Sapwood colour distinct from heartwood colour. Basic specific gravity 0.31–0.41–0.54 g/cm³.
Vessels. Wood diffuse-porous. Vessels arranged in no specific pattern, in multiples, commonly short (2–3 vessels) radial rows. Average tangential vessel diameter 90–160–210 µm. Average number of vessels/mm² 2–10–25. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 9–11 µm, not vestured. Vessel-ray pits with reduced borders or apparently simple, similar to intervessel pits or different from intervessel pits, rounded or angular or horizontal to vertical, of uniform size or type. Helical thickenings absent. Tyloses in vessels present, thinwalled.
Tracheids and fibres. Fibres very thin-walled to of medium wall thickness. Average fibre length 635–1110–1810 µm. Fibre pits mainly restricted to radial walls, simple to minutely bordered. Fibres exclusively septate. Septate fibres evenly distributed.
Axial parenchyma. Axial parenchyma paratracheal. Paratracheal axial parenchyma scanty. Axial parenchyma as strands. Average number of cells per axial parenchyma strand 5–9.
Rays. Rays 5–9 per tangential mm, multiseriate, also if only few, 2–3 cells wide. Rays composed of two or more cell types. Heterocellular rays square and upright cells restricted to marginal rows. Number of marginal rows of upright or square cells 1, or 2–4. Sheath cells absent.
Storied structures. Storied structure present or absent (storied arrangement (of rays) infrequent and irregular), all rays storied. Arrangement of tiers irregular.
Secretory structures. Oil and mucilage cells absent. Intercellular canals absent.
Mineral inclusions. Crystals present (infrequent), prismatic, located in ray cells. Crystal-containing ray cells upright and/or square, upright and/or square ray cells not chambered. Number of crystals per cell or chamber more than one. Crystals in one cell or chamber of two distinct sizes. Crystal containing cells of normal size. Silica present, as grains, in rays cells.
Miscellaneous. • Wood surface. Aucoumea klaineana. • Transverse section. Aucoumea klaineana. • Tangential section. Aucoumea klaineana. • Radial section. Aucoumea klaineana.
Cite this publication as: H. G. Richter and M. J. Dallwitz (2000 onwards). 'Commercial timbers: descriptions, illustrations, identification, and information retrieval.' In English, French, German, and Spanish. Version: 4th May 2000. http://biodiversity.uno.edu/delta/.
Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993 onwards, 1995 onwards, 1998) should also be cited (see General references).
