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Nomenclature etc. BETULACEAE. Incl. B. pubescens, B. verrucosa (syn. = B. pendula); B. alleghaniensis, B. lenta, B. papyrifera; B. schmidtii, B. alnoides. Trade and local names: commercially three types of birch timbers are distinguished: "heavy" includes B. alleghaniensis - yellow birch (US, CA); B. lenta - sweet birch, black birch (US, CA); B. schmidtii - Japanese hard birch (onoore); "moderately heavy": B. maximowicziana - Eastasian birch (saibada) and European species such as B. pubescens, B. verrucosa - European birch, common birch (GB), berken (NL), bouleau (FR), abedul (ES); "light": B. papyrifera - paper birch (US, CA); B. populifera - gray birch, wire birch (US, CA); B. alnoides - Indian birch (layang), Burma "mahogany". Not protected under CITES regulations.
Tree. Geographic distribution: Europe, excl. Mediterranean, temperate Asia, Myanmar (Burma), North America.
General. Growth ring boundaries distinct. Heartwood basically yellow to white or grey to red, brown (heavier timbers yellowish brown to red brown). Sapwood colour similar to heartwood colour, or distinct from heartwood colour. Density 0.46–0.61–0.8 g/cm³ (average density "heavy": 0.70, "moderately heavy": 0.60, "light": 0.55).
Vessels. Wood diffuse porous. Vessels in multiples, commonly in short (2–3 vessels) radial rows (occasionally also in radial chains of 4–6). Average tangential vessel diameter 30–90–130 µm. Average number of vessels/mm² 40–60. Perforation plates scalariform, with (6–)10–20(–25) bars. Intervessel pits alternate, average diameter (vertical) 3–4 µm. Vessel-ray pits with distinct borders, similar to intervessel pits, located throughout the ray. Helical thickenings absent.
Tracheids and fibres. Fibres of medium wall thickness. Average fibre length 300–1000–1700 µm. Fibre pits mainly restricted to radial walls, distinctly bordered. Fibres non-septate.
Axial parenchyma. Axial parenchyma banded. Bands marginal (or seemingly marginal). Bands fine. Axial parenchyma apotracheal. Apotracheal axial parenchyma diffuse, or diffuse-in-aggregates. Axial parenchyma as strands. Average number of cells per strand: 6–8–10.
Rays. Rays 10–17–20 per tangential mm, multiseriate, (1–)2–4 cells wide. Aggregate rays absent. Height of large rays up to 500 µm. Rays composed of a single cell type (homocellular); homocellular ray cells procumbent.
Mineral inclusions. Crystals not observed. Silica not observed.
Illustrations. • Macroscopic images. transverse (ca. 10x). radial (natural size). • Transverse section. Betula pendula. • Tangential section. Betula pendula. • Radial section. Betula pendula. • Perforation plates; intervessel pits. Betula pendula. scalariform perforation plates, minute intervessel and vessel-ray pits.
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’.
