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Nomenclature etc. PROTEACEAE. Trade and local names: Australische Silbereiche (DE); silver oak, southern silky oak, Australian silver oak (GB, US); he-oka (ZA); Australiese solwereik (NL). Not protected under CITES regulations.
Description based on 3 specimens. Tree. Geographic distribution: Australia (planted worldwide as ornamental tree).
General. Heartwood basically brown, red, yellow. Sapwood colour distinct from heartwood colour. Density 0.5–0.59–0.65 g/cm³. With conspicuous silver grain (high rays) on radial surface.
Vessels. Wood diffuse porous. Vessels arranged in tangential bands or no specific pattern (vessels often grouped in clusters or short tangential rows), in multiples, commonly in clusters. Average tangential vessel diameter 100–140–200 µm. Average number of vessels/mm² 7–10. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 6–8 µm. Vessel-ray pits with distinct borders, similar to intervessel pits. Helical thickenings present, only in narrow vessel elements, throughout the body of vessel elements. Other deposits present (brown).
Tracheids and fibres. Fibres of medium wall thickness. Fibre pits common in both radial and tangential walls, simple to minutely bordered or distinctly bordered.
Axial parenchyma. Axial parenchyma banded. Bands not marginal (or seemingly marginal). Axial parenchyma bands forming a scalariform pattern with rays. Bands coarse. Axial parenchyma apotracheal, or paratracheal. Apotracheal axial parenchyma diffuse-in-aggregates. Paratracheal axial parenchyma unilateral. Axial parenchyma as strands. Average number of cells per strand: 2–4(–6).
Rays. Rays 1(–4) per tangential mm, multiseriate, 1–15 cells wide. Rays of two distinct sizes. Height of large rays commonly over 1000 µm. Rays composed of a single cell type (homocellular) and 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. Sheath cells present.
Mineral inclusions. Crystals not observed. Cystoliths absent. Silica not observed.
Physical and chemical tests. Heartwood not fluorescent. Water extract fluorescent; colour of water extract colourless to brown. Heartwood extractives not leachable by water. Ethanol extract fluorescent. Colour of ethanol extract yellow. Weak yellowish fluorescence of water and ethanol extracts. Chrome azurol-S test positive. Splinter burns to full ash.
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’.
