Commercial Timbers

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H. G. Richter and M. J. Dallwitz

Dyera costulata (Miq.) Hook.f. (Jelutong)

Nomenclature etc. APOCYNACEAE. Additional species: Dyera polyphylla (Miq.) v. Steenis. Trade and local names: yeluu-tong, luu-tong (MY); jelutung (ID); teen-pet daeng (TH). Not protected under CITES regulations.

Description based on 4. Tree. Geographic distribution: Thailand, Laos, Vietnam, Cambodia to Indomalesia.

General. Growth ring boundaries indistinct or absent. Heartwood basically yellow, without streaks. Sapwood colour similar to heartwood colour. Odour indistinct or absent. Density 0.3–0.5 g/cm³.

Vessels. Vessels present. Wood diffuse-porous. Vessels arranged in no specific pattern, in multiples, commonly short (2–3 vessels) radial rows or radial rows of 4 or more. Vessel outline rounded. Average tangential vessel diameter 90–140–160 µm. Average number of vessels/mm² 3–10. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 4–7 µm, vestured or not vestured. Intervessel pits described as: "obscurely vestured" (Lemmens & al. 1995: PROSEA 5(2), Timber trees: Minor commercial species). Vessel-ray pits with distinct borders, similar to intervessel pits. Helical thickenings absent. Tyloses in vessels absent. Other deposits in heartwood vessels not observed.

Tracheids and fibres. Vascular or vasicentric tracheids sporadic to absent. Fibres very thin-walled, or of medium wall thickness. Average fibre length 900–1500 µm. Fibre pits mainly restricted to radial walls, simple to minutely bordered or distinctly bordered. Helical thickenings absent. Fibres non-septate.

Axial parenchyma. Axial parenchyma present, not banded. Axial parenchyma apotracheal and paratracheal. Apotracheal axial parenchyma diffuse-in-aggregates (forming a subtle network between rays). Paratracheal axial parenchyma scanty. Axial parenchyma as strands. Average number of cells per axial parenchyma strand 2–4.

Rays. Rays present, 4–8 per tangential mm, multiseriate (also if only few), (1–)2–4 cells wide. 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 or mostly 2–4 marginal rows of upright or square cells.

Storied structures. Storied structure absent.

Secretory structures. Oil and mucilage cells absent. Intercellular canals absent. Laticifers or tanniniferous tubes present (laticifers in rays). Wood often forms large and dark latex traces.

Cambial variants. Included phloem absent.

Mineral inclusions. Crystals not observed. Silica not observed.

Physical and chemical tests. Heartwood not fluorescent.

Illustrations. • Macro images. Dyera costulata. Transverse. Longitudinal. • Transverse section. Dyera costulata. • Tangential section. Dyera costulata. Note: latex tubes in rays (blow-up left). • Radial section. Dyera costulata.


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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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