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Commercial timbers

H.G. Richter and M.J. Dallwitz

Aglaia spp. (Bekak, pasak, tasua)

Nomenclature etc. MELIACEAE. Aglaia spp. including the species formerly attributed to the genus Amoora. Trade and local names: parak, langsat (ID); bekak, pasak, segera, pak (MY); makaasim, katong (PH); thanatka-wa (MM); chomnay poveang (KH); tasua, sangkhriat (TH). Not protected under CITES regulations.

Tree. Geographic distribution: Myanmar (Burma), Thailand, Laos, Vietnam, Cambodia, Indomalesia, Pacific Islands, Australia.

General. Growth ring boundaries indistinct or absent. Heartwood basically brown to red; without streaks. Sapwood colour distinct from heartwood colour. Odour distinct (in some species), or indistinct or absent. Density 0.45–0.9 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 110–160 µm. Average number of vessels/mm² 8–11. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 3–4 µm. Vessel-ray pits with distinct borders, similar to intervessel pits. Helical thickenings absent. Tyloses absent. Other deposits present (light to dark reddish brown).

Tracheids and fibres. Fibres of medium wall thickness to very thick-walled. Average fibre length 1000–1600 µm. Fibre pits mainly restricted to radial walls, simple to minutely bordered. Fibres exclusively septate; evenly distributed.

Axial parenchyma. Axial parenchyma present, banded (occasionally) or not banded. Bands not marginal (or seemingly marginal). Bands fine. Apotracheal axial parenchyma diffuse, or diffuse-in-aggregates. Paratracheal axial parenchyma vasicentric, or aliform, or confluent. Aliform parenchyma of the lozenge type, or of the winged type. Axial parenchyma as strands. Average number of cells per strand: 4–8.

Rays. Rays 7–11 per tangential mm, multiseriate, (1–)2(–3) 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 to mostly 2–4 marginal rows of upright or square cells. Some specimens show exclusively uniseriate rays; as this feature is not characteristic for the entire group it is not coded.

Storied structures. Storied structure absent.

Secretory structures. Oil and mucilage cells absent. Intercellular canals absent. Laticifers or tanniniferous tubes absent.

Cambial variants. Included phloem absent.

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

Physical and chemical tests. Froth test negative.

Illustrations. • Transverse section. Aglaia laevigata ("aglaia" type). Aglaia cucullata ("amoora" type). • Tangential section: Aglaia laevigata. Aglaia laevigata. septate fibres, septae numerous and in nearly every fibre. • Tangential section - Aglaia cucullata. Aglaia cucullata. • Radial section: Aglaia laevigata. Aglaia laevigata: rays uniformly homocellular. chambered crystalliferous parenchyma cells. • Radial section: Aglaia cucullata. Aglaia cucullata: rays partly heterocellular.


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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: 9th April 2019. delta-intkey.com’.

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