Commercial Timbers


H. G. Richter and M. J. Dallwitz

Parashorea spp. (Urat mata, white seraya, gerutu)

Nomenclature etc. DIPTEROCARPACEAE. Light weight timbers: Parashorea macrophylla, P. malaanonan, P. tomentella; heavy timbers: P. aptera, P. densiflora, P. lucida, P. parviflora, P. smythiesii, P. stellata. Trade and local names: light weight timbers: Weißes seraya, w. lauan (DE); white seraya, urat mata (MY-sab); seraya puteh (MY-sar); white lauan, bagtikan (PH); pendan (ID). heavy timbers: heavy white seraya, urat mata batu (MY-sab), gerutu, meranti gerutu (MY); khai kheo, khiansai (TH); thinkadu, tavoy wood (MM); cho chi (VN); may nao (LA); comment: this timber group is not to be mixed up with the trade timber 'white meranti' (Shorea/anthoshorea). Not protected under CITES regulations.

Tree. Geographic distribution: Burma, Thailand, Laos, Vietnam, Cambodia, and Indomalesia.

General. Heartwood basically white or grey and brown (light-weight timbers light brown with pinkish hue) green and brown (heavy timbers olive brown), heavy timbers only with streaks. Sapwood colour similar to heartwood colour, or distinct from heartwood colour. Density 0.35–0.63 g/cm³ (light-weight timbers), or 0.6–0.8 g/cm³ (heavy timbers).

Vessels. Wood diffuse-porous. Vessels in multiples, commonly short (2–3 vessels) radial rows. Average tangential vessel diameter 180–280 µm. Average number of vessels/mm² 3–7. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 5–7 µm, vestured. Vessel-ray pits with distinct borders or with reduced borders or apparently simple, similar to intervessel pits or different from intervessel pits, rounded or angular (round to oval). Tyloses in vessels present, thinwalled.

Tracheids and fibres. Vascular or vasicentric tracheids commonly present. Fibres of medium wall thickness. Fibre pits common in both radial and tangential walls, distinctly bordered.

Axial parenchyma. Axial parenchyma rare apotracheal, or paratracheal. Apotracheal axial parenchyma diffuse-in-aggregates. Paratracheal axial parenchyma vasicentric, aliform, confluent, and unilateral. Aliform parenchyma winged. Axial parenchyma as strands. Average number of cells per axial parenchyma strand 4.

Rays. Rays 4–6 per tangential mm, multiseriate (also if only few), (2–)4–7 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. Sheath cells only Parashorea lucida present.

Storied structures. Storied structure present, axial parenchyma storied.

Secretory structures. Intercellular canals present, axial type or radial type (only P. smythiesii), in long tangential lines or in short tangential lines.

Mineral inclusions. Crystals present, prismatic, located in ray cells or axial parenchyma cells. Crystal-containing ray cells procumbent, upright and/or square ray cells chambered or not chambered. Crystals in procumbent ray cells in radial alignment. Crystal-containing axial parenchyma cells chambered, or not chambered. Number of crystals per cell or chamber one, or more than one. Silica not observed.

Illustrations. • Macro images. Parashorea sp. Transverse. Radial. • Transverse section. Parashorea spp. Note: Axial intercellular canals generally present (left) but often missing in a given specimen (right). • Tangential section. Parashorea malaanonan. • Tangential section. Parashorea smythiesii. Note: Radial intercellular canals exclusively in this particular species (P. smythiesii), in all others absent. • Radial section. Parashorea tomentella. • Crystals in rays and axial parenchyma. Parashorea spp. Prismatic crystals in all species scarce to abundant in both rays (left) and axial parenchyma (right).

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.’.