Dracontomelon dao (Blanco) Merr. & Rolfe (Dao)
Nomenclature etc. ANACARDIACEAE. Other species of Dracontomelon occasionally traded as 'dao' are: D. costatum (Borneo, Sumatra), D. lenticulatum (New Guinea). Trade and local names: dao, Pacific walnut, New Guinea walnut (trade); dahu, sengkuang, basuong (RI); unkawang (MAL-SAR); mon, laup (PNG); dao (RP); nga-bauk (BUR); phrachao-ha-phra-ong (T). Status of protection under CITES regulations: not protected.
Tree. Geographic distribution: Burma to Indomalesia.
General. Growth ring boundaries indistinct or absent. Heartwood basically greyish brown, with streaks. Sapwood colour distinct from heartwood colour. Odour indistinct or absent. Basic specific gravity 0.35–0.7 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 100–300 µm. Average number of vessels/mm² 1–3(–5). Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 10–14 µm, not vestured. Vessel-ray pits with reduced borders or apparently simple, rounded or angular or horizontal to vertical, of the same type in adjacent elements or unilaterally compound and coarse. Helical thickenings absent. Tyloses in vessels present, thinwalled.
Tracheids and fibres. Fibres very thin-walled, or of medium wall thickness. Average fibre length 1200–2000 µm. Fibre pits mainly restricted to radial walls, simple to minutely bordered. Helical thickenings absent. Fibres exclusively septate, or septate and non-septate. Septate fibres evenly distributed.
Axial parenchyma. Axial parenchyma not banded. Axial parenchyma paratracheal. Paratracheal axial parenchyma vasicentric, or aliform, or confluent. Aliform parenchyma lozenge. Axial parenchyma as strands. Average number of cells per axial parenchyma strand 2–4.
Rays. Rays 5–7 per tangential mm, multiseriate, also if only few, 2–3(–5) cells wide. Rays composed of two or more cell types. Heterocellular rays square and upright cells restricted to marginal rows. Number of marginal rows of upright or square cells 1, or 2–4. Sheath cells absent. Tile cells absent. Perforated ray cells absent. Disjunctive ray parenchyma end walls indistinct or absent.
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. Other cambial variants absent.
Mineral inclusions. Crystals present, prismatic, located in ray cells. Crystal-containing ray cells upright and/or square or procumbent, upright and/or square ray cells not chambered. Crystals in procumbent ray cells not in radial alignment. Number of crystals per cell or chamber one. Cystoliths absent. Silica not observed.
Cite this publication as: H. G. Richter and M. J. Dallwitz (2000 onwards). 'Commercial timbers: descriptions, illustrations, identification, and information retrieval.' In English, French, German, and Spanish. Version: 4th May 2000. http://biodiversity.uno.edu/delta/.
Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993 onwards, 1995 onwards, 1998) should also be cited (see General references).