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H. G. Richter and M. J. Dallwitz

Irvingia malayana Oliv. (Pau kijang)

Nomenclature etc. IRVINGIACEAE. Trade and local names: Pau kijang (MY); kabok (TH). Not protected under CITES regulations.

Tree. Geographic distribution: Thailand, Laos, Vietnam, Cambodia to Indomalesia.

General. Growth ring boundaries indistinct or absent. Heartwood basically light brown yellow to white or grey, without streaks. Sapwood colour similar to heartwood colour. Odour indistinct or absent. Density 0.8–1.1 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 145–220(–300) µm; diameter of vessel lumina: large to very large. Average number of vessels/mm² (2–)3–5(–7); vessels per square millimetre very few to few. Average vessel element length 400–650(–800) µm. Average vessel element length medium. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 7–10 µm, medium, not vestured. Vessel-ray pits with reduced borders or apparently simple, rounded or angular or horizontal to vertical, of uniform size or type or of two distinct sizes or types in the same ray cell, of the same type in adjacent elements or unilaterally compound and coarse. Helical thickenings absent. Tyloses in vessels present, thinwalled or sclerotic. Other deposits in heartwood vessels not observed.

Tracheids and fibres. Vascular or vasicentric tracheids sporadic to absent. Fibres very thick-walled. Average fibre length 1650–2200 µm. Average fibre length long. 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 not marginal (or seemingly marginal), reticulate, fine, up to three cells wide. Axial parenchyma paratracheal. Paratracheal axial parenchyma aliform to confluent. Axial parenchyma as strands. Average number of cells per axial parenchyma strand 6–13. Axial parenchyma cells frequently sclerotic.

Rays. Rays 7–15 per tangential mm, multiseriate (also if only few), 2–3 cells wide, narrow (2–3 seriate). Height of large rays up to 500 µm to commonly 500 to 1000 µm. 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. Perforated ray cells absent.

Storied structures. Storied structure absent.

Secretory structures. Intercellular canals absent.

Mineral inclusions. Crystals present, prismatic, located in ray cells or axial parenchyma cells or tyloses. Crystal-containing ray cells procumbent. Crystal-containing axial parenchyma cells chambered, or not chambered. Number of crystals per cell or chamber one. Silica not observed.

Illustrations. • Transverse section. Irvingia malayana. • Tangential section. Irvingia malayana. • Radial section. Irvingia malayana.


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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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