Commercial Timbers


H. G. Richter and M. J. Dallwitz

Oxystigma spp. (Tchitola)

Nomenclature etc. FABACEAE-CAESALPINIOIDEAE. Oxystigma oxyphyllum (Harms) J. Léonard (syn.: Pterygopodium oxyphyllum Harms), O. buchholzii Harms, O. gilbertii J. Léonard, O. mannii (Oliv.) Harms. Trade and local names: tchitola, kitola (CG); lolagbola (NG); emola, m'babou (GA); tschibudimbu, akwakwa (CD); tola chinfuta (AO). Not protected under CITES regulations.

Description based on 4, or 12. Tree. Geographic distribution: tropical Africa.

General. Growth ring boundaries indistinct or absent. Heartwood basically brown to red, with streaks to without streaks. Sapwood colour distinct from heartwood colour. Odour indistinct or absent. Density 0.55–0.65 g/cm³. Wood often very resinous with dark exudations.

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 150–250 µm; diameter of vessel lumina: large to very large. Average number of vessels/mm² 2–4; vessels per square millimetre very few. Average vessel element length 130–300 µm. Average vessel element length short. Wood with rather large, diffusely distributed resin canals which cannot be distinguished from vessels macroscopically (number of vessels/mm² up to 10 including resin canals). Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 4–6 µm, minute to small, 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, brown gum deposits quite frequent.

Tracheids and fibres. Vascular or vasicentric tracheids sporadic to absent. Fibres very thin-walled, or of medium wall thickness. Average fibre length 900–1600(–1900) µm. Average fibre length medium. Fibre pits mainly restricted to radial walls, simple to minutely bordered. Helical thickenings absent. Fibres non-septate.

Axial parenchyma. Axial parenchyma present, banded. Axial parenchyma bands marginal (or seemingly marginal), fine, up to three cells wide to coarse, more than three cells wide. Axial parenchyma paratracheal. Paratracheal axial parenchyma vasicentric, or aliform, or confluent. Aliform parenchyma lozenge. Axial parenchyma as strands. Average number of cells per axial parenchyma strand 2–4. Unlignified parenchyma absent.

Rays. Rays present, 6–8 per tangential mm, multiseriate (also if only few), (1–)2–4(–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 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 to mostly 2–4 marginal rows of upright or square cells. Sheath cells absent. Tile cells absent. Perforated ray cells absent. Disjunctive ray parenchyma end walls indistinct or absent. Rays occasionally also homocelular.

Storied structures. Storied structure absent.

Secretory structures. Oil and mucilage cells absent. Intercellular canals present, non-traumatic origin, axial type, diffusely arranged. Resin canals often as large as vessels and therefore not distinct macroscopically. Laticifers or tanniniferous tubes absent.

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

Mineral inclusions. Crystals present or not observed, 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. Crystals very few and in some specimens absent. Silica not observed.

Illustrations. • Transverse section. Oxystigma oxyphyllum. • Tangential section. Oxystigma oxyphyllum. • Radial section. Oxystigma oxyphyllum. • Miscellaneous. Oxystigma oxyphyllum. Vessel (right) with cellwall and axial intercellular canal (left) with traces of epithelial cells.

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.’.