Nomenclature etc. STERCULIACEAE. Pterocymbium beccari K. Schumann, P. tinctorium (Blanco) Merr., P. tubulatum (Masters) Pierre. Trade and local names: Amberoi (trade); kelumbuk, papita (ID); melembu, teluto, keluak (MY); taluto (PH); sawbya (MM); oi-chang, po-ikeng, po-kradang (TH). Not protected under CITES regulations.
Tree. Geographic distribution: Burma to Indomalesia.
General. Growth ring boundaries indistinct or absent. Heartwood basically yellow to white or grey, without streaks. Sapwood colour similar to heartwood colour. Odour indistinct or absent. Density 0.23–0.4 g/cm³.
Vessels. Wood diffuse-porous. Vessels arranged in no specific pattern, in multiples, commonly short (2–3 vessels) radial rows. Average tangential vessel diameter 220–350 µm. Average number of vessels/mm² 1–2(–4). Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 5–7 µm, small, not vestured. Vessel-ray pits with distinct borders, similar to intervessel pits. Helical thickenings absent. Tyloses in vessels absent.
Tracheids and fibres. Vascular or vasicentric tracheids sporadic to absent. Fibres very thin-walled. Average fibre length 1100–2100 µm. Fibre pits mainly restricted to radial walls, simple to minutely bordered. Helical thickenings absent. Fibres non-septate.
Axial parenchyma. Axial parenchyma not banded. Axial parenchyma apotracheal and paratracheal. Apotracheal axial parenchyma diffuse-in-aggregates. Paratracheal axial parenchyma vasicentric. Axial parenchyma as strands. Average number of cells per axial parenchyma strand 2–4. Unlignified parenchyma absent.
Rays. Rays 2–4 per tangential mm (only large rays), multiseriate (also if only few), 5–12(–20) cells wide. Rays with multiseriate portions as wide as uniseriate portions absent. Aggregate rays absent. Rays of two distinct sizes. 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 1 marginal row of upright or square cells to mostly 2–4 marginal rows of upright or square cells. Sheath cells present. Tile cells absent. Perforated ray cells absent. Disjunctive ray parenchyma end walls indistinct or absent.
Storied structures. Storied structure present, some rays storied, some not, axial parenchyma storied, vessel elements storied, fibres storied. Arrangement of tiers regular (horizontal or straight). Number of ray tiers per axial millimetre 5–6.
Secretory structures. Oil and mucilage cells absent. Intercellular canals present, traumatic origin (exclusively), axial type, in short tangential lines. Laticifers or tanniniferous tubes absent.
Cambial variants. Included phloem absent. Other cambial variants absent.
Mineral inclusions. Crystals present, prismatic and druses, located in ray cells. Crystal-containing ray cells upright and/or square or procumbent (including sheath cells), upright and/or square ray cells not chambered. Crystals in procumbent ray cells not in radial alignment. Number of crystals per cell or chamber one. Crystal containing cells of normal size. Cystoliths absent. Silica not observed.
Illustrations. • Transverse section. Pterocymbium beccarii. • Tangential section. Pterocymbium beccarii. • Radial section. Pterocymbium beccarii. • Crystals + silica in rays. Pterocymbium beccarii. Crystal druses )CR) and silica (SI) particles in ray cells. CR. CR. SI. SI.
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’.