Commercial Timbers

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H. G. Richter and M. J. Dallwitz

Hopea spp. (Giam)

Nomenclature etc. DIPTEROCARPACEAE. Hopea ferrea, H. forbesii, H. helferi, H. nutans, H. semicuneata, etc. Trade and local names: giam (MY, trade); luis (BN); yakal (PH); heavy hopea (PG, GB); thingyan (MM); koki (KH); takhian-rak, takhian-hin (TH); sao xanh (VN). Not protected under CITES regulations.

Tree. Geographic distribution: Burma to Indomalesia.

General. Heartwood basically brown to yellow. Sapwood colour distinct from heartwood colour. Density 0.83–1.15 g/cm³.

Vessels. Wood diffuse-porous. Vessels in multiples, commonly short (2–3 vessels) radial rows. Average tangential vessel diameter (60–)110–160 µm. Average number of vessels/mm² 15–30(–80). Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 4–6 µm, vestured. Vessel-ray pits with reduced borders or apparently simple, rounded or angular (round to oval). Tyloses in vessels present, thinwalled.

Tracheids and fibres. Fibres very thick-walled. Average fibre length 1200–2200 µm. Fibre pits mainly restricted to radial walls, simple to minutely bordered.

Axial parenchyma. Axial parenchyma banded. Banded parenchyma only connecting axial intercellular canals. Axial parenchyma apotracheal, or paratracheal. Apotracheal axial parenchyma diffuse-in-aggregates. Paratracheal axial parenchyma scanty, or vasicentric, or aliform, or confluent. Aliform parenchyma winged. Axial parenchyma as strands. Average number of cells per axial parenchyma strand 4–6.

Rays. Rays 8–11 per tangential mm, multiseriate (also if only few), (1–)2–5 cells wide. Height of large rays commonly 500 to 1000 µm, or commonly over 1000 µm. Rays composed of two or more cell types (heterocellular). Heterocellular rays with square and upright cells restricted to marginal rows or procumbent, square and upright cells mixed throughout the ray, mostly 1 marginal row of upright or square cells or mostly 2–4 marginal rows of upright or square cells. Sheath cells present (in some species present, absent in others).

Storied structures. Storied structure present (pronounced only in H. ferrea) or absent, all rays storied, axial parenchyma storied, vessel elements storied, fibres storied. Arrangement of tiers regular (horizontal or straight), or irregular. Number of ray tiers per axial millimetre 3.

Secretory structures. Intercellular canals present, non-traumatic origin, axial type, in long tangential lines or in short tangential lines.

Mineral inclusions. Crystals present, prismatic or druses (druses only sporadically), located in ray cells. Crystal-containing ray cells upright and/or square or procumbent. Crystals in procumbent ray cells in radial alignment. Number of crystals per cell or chamber one. Crystal containing cells of normal size, or enlarged (idioblasts). Silica not observed.

Illustrations. • Transverse section: H. ferrea. Hopea ferrea. • Tangential section: H. ferrea. Hopea ferrea. • Radial section: H. ferrea. Hopea ferrea. • Ray composition tangential): H. nutans. Hopea nutans. Note ray composition and presence of vasicentric tracheids. • Transverse section: H. forbesii. Hopea forbesii. As opposed to Hopea ferrea in this 'giam' species, H. forbesii, vessels ar much larger, rays are non-storied, and crystals are located in axial parenchyma. • Tangential section: H. forbesii. Hopea forbesii. As opposed to Hopea ferrea in this 'giam' species, H. forbesii, vessels ar much larger, rays are non-storied, and crystals are located in axial parenchyma. • Radial section: H. forbesii. As opposed to Hopea ferrea in this 'giam' species, H. forbesii, vessels ar much larger, rays are non-storied, and crystals are located in axial parenchyma. Hopea forbesii.


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. http://delta-intkey.com’.

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