Commercial Timbers


H. G. Richter and M. J. Dallwitz

Pterygota bequaertii De Wild., P. macrocarpa K. Schum. (Koto)

Nomenclature etc. STERCULIACEAE. Syn.: Sterculia thompsonii Hutch.&Dalz., Pterygota cordifolia A.Chev. Trade and local names: koto (DE, CI) akodiakédé, bofo ouale, bontue, pohoure, waré (CI); Pterygota (GB); awari, kyere, wawampe (GH); efok, kion (CM); kefe, poroporo, oporipo (NG); aké (GA); ikame (CD); kakende (CF. Not protected under CITES regulations.

Tree. Geographic distribution: tropical Africa (further species in Southeast Asia and in tropical America).

General. Growth ring boundaries distinct. Heartwood basically yellow to white or grey, without streaks. Sapwood colour similar to heartwood colour. Density 0.46–0.55–0.63 g/cm³.

Vessels. Wood diffuse-porous. Vessels in multiples, commonly short (2–3 vessels) radial rows. Average tangential vessel diameter 95–180–240 µm. Average number of vessels/mm² 1–4. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 5–7 µm. Vessel-ray pits with distinct borders, similar to intervessel pits. Helical thickenings absent. Other deposits in heartwood vessels present.

Tracheids and fibres. Fibres of medium wall thickness. Average fibre length 1265–1785–2780 µm. Fibre pits common in both radial and tangential walls, simple to minutely bordered.

Axial parenchyma. Axial parenchyma banded. Axial parenchyma apotracheal and paratracheal. Apotracheal axial parenchyma diffuse-in-aggregates (sporadically). Paratracheal axial parenchyma scanty and vasicentric. Axial parenchyma as strands. Average number of cells per axial parenchyma strand (3–)4(–6).

Rays. Rays 3–5 per tangential mm, multiseriate (also if only few), 1–5–7 cells wide. Height of large rays commonly over 1000 µm. Rays composed of two or more cell types (heterocellular). Heterocellular rays with square and upright cells restricted to marginal rows, mostly 2–4 marginal rows of upright or square cells. Sheath cells present.

Storied structures. Storied structure present, axial parenchyma storied, vessel elements not storied.

Secretory structures. Intercellular canals absent.

Mineral inclusions. Crystals present, prismatic, located in ray cells and axial parenchyma cells. Crystal-containing ray cells upright and/or square and procumbent (less frequent in procumbent cells). Crystals in procumbent ray cells in radial alignment. Crystal-containing axial parenchyma cells not chambered. Number of crystals per cell or chamber one. Silica not observed.

Illustrations. • Macro images. Pterygota sp. Transverse. Tangential. • Transverse section. Pterygota macrophylla. • Tangential section. Pterygota macrophylla. • Radial section. Pterygota macrophylla.

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.’.