Commercial Timbers


H. G. Richter and M. J. Dallwitz

Arbutus spp. (Madroño)

Nomenclature etc. ERICACEAE. Arbutus andrachne L., A. menziesii Pursh, A. unedo L. Trade and local names: Erdbeerbaum (DE); manzanita, madrona (ES); strawberry tree, killarney strawberry, Irish strawberry (GB); arbousier (FR); arbuso, corbezzolo (IT); ervedeiro, medronheiro (PT). Not protected under CITES regulations.

Description based on 6. Tree. Geographic distribution: Europe, excl. Mediterranean, or Mediterranean incl. N. Africa and Middle East (A. andrachne, A. unedo), or North America (A. menziesii).

General. Growth ring boundaries distinct. Heartwood basically brown (green wood mostly pinkish brown), with streaks (occasionally). Sapwood colour distinct from heartwood colour. Density 0.7–0.9 g/cm³.

Vessels. Wood semi-ring-porous to diffuse-porous. Vessels arranged in no specific pattern, in multiples, commonly short (2–3 vessels) radial rows. Vessel outline rounded, or angular. Average tangential vessel diameter (15–)30–40(–60) µm; diameter of vessel lumina: small. Average number of vessels/mm² (50–)100–130(–260); vessels per square millimetre very numerous. Average vessel element length (140–)400(–650) µm. Average vessel element length medium. Perforation plates simple and scalariform, with 1–6 bars. Perforation plates are predominantly simple in A. andrachne and A. unedo with only few scalariform plates in latewood vessels; in A. menziesii perforation plates are almost all scalariform.. Intervessel pits alternate, average diameter (vertical) 3–5 µm, minute to small. Vessel-ray pits with distinct borders (most likely, difficult to see), similar to intervessel pits. Helical thickenings present, in narrow and wide vessel elements, throughout the body of vessel elements. Other deposits in heartwood vessels present (amber or brown).

Tracheids and fibres. Vascular or vasicentric tracheids commonly present (vascular, with spiral thickenings). Fibres of medium wall thickness to very thick-walled. Average fibre length (500–)750(–1000) µm. Average fibre length short to medium. Fibre pits common in both radial and tangential walls, distinctly bordered. Fibres septate and non-septate. Septate fibres scattered near vessels and rays.

Axial parenchyma. Axial parenchyma present (however extremely rare). Axial parenchyma apotracheal. Apotracheal axial parenchyma diffuse (frequently as cristalliferous chambered cells). Axial parenchyma as strands. Average number of cells per axial parenchyma strand 2–4.

Rays. Rays 4–8 per tangential mm, multiseriate (also if only few), 1–3(–4) cells wide, narrow (2–3 seriate) to of medium width (3–5 seriate). Height of large rays up to 500 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 or mostly 2–4 marginal rows of upright or square cells.

Mineral inclusions. Crystals present, prismatic, located in ray cells and axial parenchyma cells. Crystal-containing ray cells upright and/or square, upright and/or square ray cells chambered. Crystal-containing axial parenchyma cells chambered. Number of crystals per cell or chamber one, or more than one. Crystals in one cell or chamber of two distinct sizes. Silica not observed.

Physical and chemical tests. Heartwood not fluorescent. Water extract not fluorescent; basically colourless to brown or shade of brown. Ethanol extract fluorescent (weakly yellow orange). Colour of ethanol extract colourless to brown or shade of brown. Chrome azurol-S test negative. Froth test positive (very strong). Splinter burns to full ash. Ash white to grey.

Illustrations. • Transverse section. Arbutus unedo. • Tangential section. Arbutus unedo. • Radial section. Arbutus unedo. • Miscellaneous 1. Arbutus menziesii. Arbutus unedo. Scalariform perforation plates frequent in:. Scalariform perforation plates rare in:. • Miscellaneous 2. Spiral thickenings in vessels very numerous in all species. Arbutus menziesii.

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: 25th June 2009.’.