Commercial Timbers


H. G. Richter and M. J. Dallwitz

Brachystegia spp. (Naga, okwen)

Nomenclature etc. FABACEAE-CAESALPINIOIDEAE. Brachystegia cynometroides Harms, B. eurycoma Harms, B. leonensis Hutch. & Davy, B. nigerica Hoyle & A.P.D. Jones, etc. Trade and local names: naga, ekop-naga (CM); bogdei, tebako (LR); okwen (NG); mendou (GA); meblo (CI). Not protected under CITES regulations.

Tree. Geographic distribution: tropical Africa.

General. Growth ring boundaries distinct. Growth ring limits marked by marginal parenchyma bands. Heartwood basically brown yellow, without streaks. Sapwood colour distinct from heartwood colour. Density 0.6–0.72 g/cm³.

Vessels. Wood diffuse-porous. Vessels in multiples, commonly short (2–3 vessels) radial rows. Average tangential vessel diameter 100–190 µm. Average number of vessels/mm² 3–10. Average vessel element length 150–400 µm. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 5–7 µm, vestured. Vessel-ray pits with distinct borders, similar to intervessel pits. Other deposits in heartwood vessels present (yellowish to brown).

Tracheids and fibres. Fibres of medium wall thickness. Average fibre length 720–1750 µm. Fibre pits mainly restricted to radial walls, simple to minutely bordered. Fibres non-septate.

Axial parenchyma. Axial parenchyma banded. Axial parenchyma bands marginal (or seemingly marginal), fine, up to three cells wide or coarse, more than three cells wide. Axial parenchyma paratracheal. Paratracheal axial parenchyma aliform, or confluent. Aliform parenchyma lozenge. Axial parenchyma as strands. Average number of cells per axial parenchyma strand 4–8(–12).

Rays. Rays (10–)14–17(–19) per tangential mm, exclusively uniseriate. Rays composed of a single cell type (homocellular); homocellular ray cells procumbent.

Storied structures. Storied structure present, all rays storied, axial parenchyma not storied. Arrangement of tiers irregular. Storeying always irregular.

Secretory structures. Intercellular canals present, traumatic origin, axial type, in long tangential lines or in short tangential lines.

Mineral inclusions. Crystals present, prismatic, located in axial parenchyma cells. Crystal-containing axial parenchyma cells chambered. Number of crystals per cell or chamber one. Silica not observed.

Illustrations. • Transverse section. Brachystegia cynometroides.. Note the quantitative variation (vessel diameter, banded parenchyma) in different specimens of a single species. • Tangential section 1. Brachystegia cynometroides (note storied arrangement of mostly uniseriate rays). • Tangential section 2. Brachystegia cynometroides (storied arrangement of rays hardly perceptible). • Radial section. Brachystegia cynometroides..

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.’.