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| Commercial timbers |
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: Myanmar (Burma), Thailand, Laos, Vietnam, Cambodia, Indomalesia.
General. Heartwood basically brown to yellow, green. Sapwood colour distinct from heartwood colour. Density 0.83–1.15 g/cm³.
Vessels. Wood diffuse porous. Vessels in multiples, commonly in 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, pits vestured. Vessel-ray pits with reduced borders or apparently simple, different from intervessel pits, rounded or angular (round to oval). Tyloses 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. Bands fine. Banded parenchyma only connecting axial intercellular canals. Axial parenchyma apotracheal, or paratracheal. Apotracheal axial parenchyma diffuse, or diffuse-in-aggregates. Paratracheal axial parenchyma scanty, or vasicentric, or aliform, or confluent. Aliform parenchyma of the winged type. Axial parenchyma as strands. Average number of cells per strand: 4–6.
Rays. Rays 8–11 per tangential mm, multiseriate, (1–)2–5 cells wide. Height of large rays up to 500 µm, or 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 (present in some species, absent in others), or absent.
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, or irregular. Number of ray tiers per axial millimetre 3.
Secretory structures. Intercellular canals present, oriented axially, axial intercellular canals 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.
Physical and chemical tests. Heartwood extractives leachable when in contact with water (some specimens), or not leachable by water.
Illustrations. • Transverse section: H. ferrea. Hopea ferrea. • Tangential section: H. ferrea. Hopea ferrea: rays storied. • Radial section: H. ferrea. Hopea ferrea. • Ray composition. Hopea nutans. ray composition and presence of vasicentric tracheids. • Transverse section: H. forbesii. Hopea forbesii. as opposed to Hopea ferrea, in this 'giam' species vessels are much larger, rays are not storied, and crystals are located in axial parenchyma. • Tangential section: H. forbesii. Hopea forbesii. • Radial section: H. forbesii. 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: 9th April 2019. delta-intkey.com’.
