Commercial Timbers


H. G. Richter and M. J. Dallwitz

Aucoumea klaineana Pierre (Okoumé)

Nomenclature etc. MMSERACEAE. Trade and local names: okoumé (BE, DE, FR, NL), Gaboon, Gabun (DE), angouma, okaka (GA), angum , ongoumi, moukoumi, zonga (GQ). Not protected under CITES regulations.

Tree. Geographic distribution: tropical Africa.

General. Heartwood basically brown to red to white or grey. Sapwood colour distinct from heartwood colour. Density 0.31–0.41–0.54 g/cm³.

Vessels. Wood diffuse-porous. Vessels 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. Tyloses in vessels present, thinwalled.

Tracheids and fibres. Fibres very thin-walled, or 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). Heterocellular rays with square and upright cells restricted to marginal rows, mostly 1 marginal row of upright or square cells or mostly 2–4 marginal rows of upright or square cells.

Storied structures. Storied structure present or absent (storied arrangement (of rays) only irregular), all rays storied. Arrangement of tiers irregular.

Secretory structures. Oil and mucilage cells 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.

Illustrations. • Transverse section. Aucoumea klaineana. • Tangential section. Aucoumea klaineana. • Radial section. Aucoumea klaineana. • Silica in rays. Aucoumea klaineana.

The interactive key allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting specified attributes, summaries of attributes within groups of taxa, and geographical distribution.

Cite this publication as: ‘Richter, H.G., and Dallwitz, M.J. 2000 onwards. Commercial timbers: descriptions, illustrations, identification, and information retrieval. In English, French, German, Portuguese, and Spanish. Version: 25th June 2009.’.