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H. G. Richter and M. J. Dallwitz

Cylicodiscus gabunensis (Taub.) Harms (Okan)

Nomenclature etc. FABACEAE-MIMOSOIDEAE. Syn.: Erythrophleum gabunensis Taub. Trade and local names: bokoka, adum, okan. Not protected under CITES regulations.

Description based on 8 specimens. Tree. Geographic distribution: tropical Africa.

General. Growth ring boundaries indistinct or absent. Heartwood basically brown, with streaks. Sapwood colour distinct from heartwood colour. Odour indistinct or absent. With strongly interlocked grain.

Vessels. Vessels present. Wood diffuse-porous. Vessels arranged in no specific pattern, in multiples, commonly short (2–3 vessels) radial rows. Vessel outline rounded. Two distinct vessel diameter classes absent. Average tangential vessel diameter 130–260–330 µm; diameter of vessel lumina: very large. Average number of vessels/mm² 1–4; vessels per square millimetre very few. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 7–10 µm, medium, vestured. Vessel-ray pits with distinct borders, similar to intervessel pits, of uniform size or type, of the same type in adjacent elements, located throughout the ray. Helical thickenings absent. Tyloses in vessels absent. Other deposits in heartwood vessels present, orange to red to brown deposits.

Tracheids and fibres. Vascular or vasicentric tracheids sporadic to absent. Fibres of medium wall thickness to very thick-walled. Fibre pits mainly restricted to radial walls, simple to minutely bordered. Helical thickenings absent. Fibres non-septate.

Axial parenchyma. Axial parenchyma present, not banded. Axial parenchyma paratracheal. Paratracheal axial parenchyma vasicentric, aliform, and confluent. Aliform parenchyma lozenge. Axial parenchyma as strands. Average number of cells per axial parenchyma strand 2–6. Unlignified parenchyma absent.

Rays. Rays present, 5–7 per tangential mm, multiseriate (also if only few), 3–5 cells wide, of medium width (3–5 seriate). Rays with multiseriate portions as wide as uniseriate portions absent. Aggregate rays absent. Rays of one size. Height of large rays up to 500 µm. Rays composed of a single cell type (homocellular); homocellular ray cells procumbent. Sheath cells absent. Tile cells absent. Perforated ray cells absent. Disjunctive ray parenchyma end walls indistinct or absent.

Storied structures. Storied structure absent.

Secretory structures. Oil and mucilage cells absent. Intercellular canals absent. Laticifers or tanniniferous tubes absent.

Cambial variants. Included phloem absent. Other cambial variants absent.

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

Physical and chemical tests. Heartwood fluorescent. Water extract not fluorescent; basically red or shade of red. Heartwood extractives not leachable by water. Ethanol extract not fluorescent. Colour of ethanol extract red or shade of red. Chrome azurol-S test negative. Froth test negative. Splinter burns to partial ash. Ash white to grey.

Illustrations. • Macro images. Cylicodiscus gabunensis. Transverse. Radial. • Transverse section. Cylicodiscus gabunensis. • Tangential section. Cylicodiscus gabunensis. • Radial section. Cylicodiscus gabunensis.


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. http://delta-intkey.com’.

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