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Nomenclature etc. IRVINGIACEAE. Trade and local names: kabok (TH). Not protected under CITES regulations.
Tree. Geographic distribution: Thailand, Laos, Vietnam, Cambodia, Indomalesia.
General. Heartwood basically light brown, yellow to white or grey. 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 in short (2–3 vessels) radial rows. Average tangential vessel diameter 145–220(–300) µm. Average number of vessels/mm² (2–)3–5(–7). Average vessel element length 400–650(–800) µm. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 7–10 µm. Vessel-ray pits with reduced borders or apparently simple, different from intervessel pits, 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 present, thinwalled or sclerotic.
Tracheids and fibres. Fibres very thick-walled. Average fibre length 1650–2200 µm. Fibre pits mainly restricted to radial walls, simple to minutely bordered. Fibres non-septate.
Axial parenchyma. Axial parenchyma banded. Axial parenchyma bands forming a reticulate pattern with rays. Bands fine. Axial parenchyma apotracheal, or paratracheal. Apotracheal axial parenchyma diffuse-in-aggregates. Paratracheal axial parenchyma aliform to confluent. Axial parenchyma as strands. Average number of cells per strand: 6–13. Axial parenchyma cells frequently sclerotic.
Rays. Rays 7–15 per tangential mm, multiseriate, 2–3 cells wide. 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.
Physical and chemical tests. Froth test negative.
Illustrations. • Transverse section. • Tangential section. • Radial section. sclerified tyloses in vessels.
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: 9th April 2019. delta-intkey.com’.
