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Nomenclature etc. TROCHODENDRACEAE. Trade and local names: Radbaum (DE); wheel tree (GB); yamaguruma (JP); kun lan shu (CN). Not protected under CITES regulations.
Description based on 2 specimens. Tree. Geographic distribution: temperate Asia.
General. Growth ring boundaries distinct. Rays typically noded at growth ring limits. Heartwood basically brown; without streaks. Sapwood colour similar to heartwood colour. Odour indistinct or absent.
Vessels. Vessels absent.
Tracheids and fibres. Vascular or vasicentric tracheids commonly present. Fibres very thin-walled. Fibre pits common in both radial and tangential walls, distinctly bordered. Helical thickenings absent. Fibres non-septate. Tracheids with scalariform pitting; tracheids alternating with fibres.
Axial parenchyma. Axial parenchyma absent or extremely rare. Apotracheal axial parenchyma diffuse. Axial parenchyma as strands. Average number of cells per strand: 3–6.
Rays. Rays present, 4–7 per tangential mm, multiseriate, 1–8 cells wide, wide (5–10 seriate). Rays with multiseriate portions as wide as uniseriate portions absent. Aggregate rays absent. Rays of two distinct sizes. Height of large rays commonly over 1000 µm. Rays composed of two or more cell types (heterocellular). Heterocellular rays with square and upright cells restricted to marginal rows, mostly 1 marginal row of upright or square cells and mostly 2–4 marginal rows of upright or square cells. Sheath cells absent. Tile cells absent. Perforated ray cells absent. Disjunctive ray parenchyma end walls indistinct or absent. Uniseriate rays composed solely of square and upright cells.
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 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 not fluorescent. Colour of ethanol extract colourless to brown. Chrome azurol-S test negative. Froth test positive. Splinter burns to partial ash. Ash white to grey.
Illustrations. • Transverse section. • Tangential section. • Radial section. • Intertracheid pitting. pits between tracheids.
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’.
