Oxystigma spp. (tchitola)
Nomenclature etc. CAESALPINIACEAE. Oxystigma oxyphyllum (Harms) J. Léonard, O. buchholzii Harms, O. gilbertii J. Léonard, O. mannii (Oliv.) Harms; incl. Pterygopodium. Trade and local names: tchitola, kitola (RPC); lolagbola (WAN); emola, m'babou (G); tschibudimbu, akwakwa (ZRE); tola chinfuta (ANG). Status of protection under CITES regulations: not protected.
Description based on: 4 species/specimens, or 12 species/specimens. 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. Basic specific gravity 0.55–0.65 g/cm³. Wood often very resinous with dark exsudation.
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. Average tangential 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) 3–8 µm, minute to small, vestured. Intervessel pit size rather variable; in Oxystigma oxyphyllum (syn.: Pterygopodium oxyphyllum) small (3–5µm), in the other species around 6–7(-8)µm. 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 to 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, commonly 3–5 cells wide. 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 rays square and upright cells restricted to marginal rows. Number of marginal rows of upright or square cells 1 to 2–4. 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 sparse and in some specimens absent. Silica not observed.
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).