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H. G. Richter and M. J. Dallwitz

Shorea laevis Ridl. (Balau, bangkirai)

Nomenclature etc. DIPTEROCARPACEAE. Syn.: Shorea laevifolia (Parijs) Endert, Hopea laevifolia Parijs. Trade and local names: bangkirai (ID), balau, selangan batu No.1 (trade, MY). Not protected under CITES regulations.

Tree. Geographic distribution: India, Pakistan, Sri Lanka, Burma, Thailand, Laos, Vietnam, Cambodia, and Indomalesia.

General. Heartwood basically brown to yellow to white or grey brown to green. Sapwood colour distinct from heartwood colour. Density 0.72–0.85–0.93 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 95–160–225 µm. Average number of vessels/mm² 3–6. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 4–6 µm, vestured. Vessel-ray pits with distinct borders and with reduced borders or apparently simple, similar to intervessel pits, rounded or angular. Tyloses in vessels present (abundant), thinwalled.

Tracheids and fibres. Vascular or vasicentric tracheids commonly present. Fibres very thick-walled. Fibre pits mainly restricted to radial walls, simple to minutely bordered.

Axial parenchyma. Axial parenchyma banded. Axial parenchyma bands marginal (or seemingly marginal), fine, up to three cells wide and coarse, more than three cells wide. Parenchyma bands include axial resin canals. Axial parenchyma rarely apotracheal, or paratracheal. Apotracheal axial parenchyma diffuse-in-aggregates. Paratracheal axial parenchyma vasicentric, aliform, confluent, and unilateral. Axial parenchyma as strands. Average number of cells per axial parenchyma strand (2–)4–5.

Rays. Rays 5–8 per tangential mm, multiseriate (also if only few), 3–4 cells wide. Rays composed of a single cell type (homocellular), or two or more cell types (heterocellular); homocellular ray cells procumbent. Heterocellular rays with square and upright cells restricted to marginal rows, mostly 1 marginal row of upright or square cells.

Storied structures. Storied structure present (not in all specimens), all rays storied or some rays storied, some not, axial parenchyma storied.

Secretory structures. Intercellular canals present, axial type, in long tangential lines and in short tangential lines.

Mineral inclusions. Crystals present or not observed, prismatic, located in axial parenchyma cells. Crystal-containing axial parenchyma cells chambered and not chambered. Number of crystals per cell or chamber one. Crystal containing cells of normal size and enlarged (idioblasts). Cystoliths absent. Prismatic crystals sporadically in axial parenchyma cells, however not in all specimens. Silica not observed.

Physical and chemical tests. Water extract basically yellow or shade of yellow. Heartwood extractives leaching out when in contact with water (yellow). Splinter burns to charcoal.

Illustrations. • Transverse section. Shorea laevis. • Tangential section. Shorea laevis. • Radial section. Shorea laevis.


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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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