Commercial Timbers


H. G. Richter and M. J. Dallwitz

Rhamnus catharticus L. (Kreuzdorn, buckthorn)

Nomenclature etc. RHAMNACEAE. Not protected under CITES regulations.

Description based on 4 specimens. Tree. Geographic distribution: Europe, excl. Mediterranean.

General. Growth ring boundaries distinct. Growth ring boundaries demarcated by radially flattened fibres (latewood) and a continuous band of earlywood pores. Heartwood basically brown, red, and yellow. Sapwood colour distinct from heartwood colour.

Vessels. Vessels present. Wood semi-ring-porous and diffuse-porous. Vessels arranged in dendritic pattern, in multiples, commonly in clusters. Almost no solitary vessels. Average tangential vessel diameter 25–38–50 µm; diameter of vessel lumina: small. Average number of vessels/mm² 100–330; vessels per square millimetre very numerous. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 6–8 µm, small and medium, not vestured. Vessel-ray pits with distinct borders, different from intervessel pits, of uniform size or type, of the same type in adjacent elements, located throughout the ray. Vessel-ray pits are smaller than intervascular pits. Helical thickenings present, in narrow and wide vessel elements, throughout the body of vessel elements. Tyloses in vessels absent. Other deposits in heartwood vessels present, deposits yellow-brown.

Tracheids and fibres. Vascular or vasicentric tracheids commonly present. Fibres very thin-walled and of medium wall thickness. Fibre pits mainly restricted to radial walls, simple to minutely bordered. Helical thickenings absent. Fibres non-septate. Tracheids with helical thickenings within groups of vessels.

Axial parenchyma. Axial parenchyma absent or extremely rare.

Rays. Rays present, 10–13 per tangential mm, multiseriate (also if only few), 1–3 cells wide, narrow (2–3 seriate). Rays with multiseriate portions as wide as uniseriate portions absent. Aggregate rays absent. Rays of one size. Height of large rays up to 500 µm. Rays composed of a single cell type (homocellular); homocellular ray cells procumbent. Sheath cells absent. Tile cells absent. Perforated ray cells absent. Disjunctive ray parenchyma end walls indistinct or absent.

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 fluorescent. Water extract fluorescent; basically colourless to brown or shade of brown. Heartwood extractives leaching out when in contact with water (little). Ethanol extract fluorescent. Colour of ethanol extract colourless to brown or shade of brown. Chrome azurol-S test negative. Froth test negative. Splinter burns to partial ash. Ash white to grey.

Illustrations. • Transverse section. Rhamnus catharticus. • Tangential section. Rhamnus catharticus. • Radial section. Rhamnus catharticus.

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.’.