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Nomenclature etc. LAURACEAE. A second species, Eusideroxylon melagangai Sym., was relegated to the monotypic genus Potoxylon by Kostermans. The wood of this species endemic to Borneo differs from 'billian' by a lower density (0.70–0.80 g/cm³), lower rays (around 0.7 mm), fibres occasionally septate, oil cells also associated with rays. Trade and local names: Borneo ironwood (GB); bois de fer (FR); belian, tambulian, im muk (MY); belian, onglen, tulian, tebelian (ID); tambulian, sakian, biliran (PH). Not protected under CITES regulations.
Tree. Geographic distribution: Indomalesia.
General. Heartwood basically brown to yellow. Sapwood colour distinct from heartwood colour. Density 0.85–1.1 g/cm³. Heartwood with yellowish to greenish (olive) hues when fresh, dark brown to almost black upon exposure.
Vessels. Wood diffuse porous. Vessels arranged in no specific pattern, in multiples, commonly in short (2–3 vessels) radial rows. Average tangential vessel diameter 150–230(–280) µm. Average number of vessels/mm² 2–7(–10). Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 8–11 µm. 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 to horizontal to vertical. Tyloses present, thinwalled or sclerotic.
Tracheids and fibres. Fibres very thick-walled. Average fibre length 1200–1900 µm. Fibre pits mainly restricted to radial walls, simple to minutely bordered. Fibres non-septate.
Axial parenchyma. Axial parenchyma not banded. Axial parenchyma apotracheal, or paratracheal. Apotracheal axial parenchyma diffuse-in-aggregates. Paratracheal axial parenchyma aliform to confluent. Aliform parenchyma of the lozenge type. Axial parenchyma as strands. Average number of cells per strand: 4–9.
Rays. Rays 8–10 per tangential mm, multiseriate, 2–3(–4) cells wide. Height of large rays commonly 500 to 1000 µm to commonly over 1000 µm (occasionally up to 3 mm high). Rays composed of a single cell type (homocellular), or two or more cell types (heterocellular) (few); homocellular ray cells procumbent. Heterocellular rays with square and upright cells restricted to marginal rows, mostly 1 marginal row of upright or square cells.
Storied structures. Storied structure absent.
Secretory structures. Oil and mucilage cells present (oil cells), associated with axial parenchyma.
Mineral inclusions. Crystals not observed. Silica not observed.
Illustrations. • Transverse section. • Tangential section. • Radial section.
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’.
