Commercial timbers

H. G. Richter and M. J. Dallwitz


Paulownia tomentosa (Thunb. ex Murr) Steud. (Kiri)

Nomenclature etc. SCROPHULARIACEAE. Syn.: Paulownia imperialis Sieb. & Zucc. Trade and local names: kiri, shima-giri (J); Paulownia (trade). Status of protection under CITES regulations: not protected.

Tree. Geographic distribution: temperate Asia (cultivated worldwide in temperate and subtropical climates).

General. Growth ring boundaries distinct. Heartwood basically white or grey, without streaks. Sapwood colour similar to heartwood colour. Odour indistinct or absent. Basic specific gravity 0.25–0.3 g/cm³.

Vessels. Vessels present. Wood ring-porous, or semi-ring-porous. Vessels arranged in no specific pattern, in multiples, commonly short (2–3 vessels) radial rows. Vessel outline angular. Average tangential vessel diameter 200–300 µm (earlywood). Average tangential diameter of vessel lumina large to very large. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 6–8 µm, small to medium. Vessel-ray pits with distinct borders or with reduced borders or apparently simple, similar to intervessel pits, rounded or angular. Helical thickenings present, only in narrow vessel elements, throughout the body of vessel elements. Tyloses in vessels present, thinwalled.

Tracheids and fibres. Fibres very thin-walled. Fibre pits mainly restricted to radial walls, simple to minutely bordered. Fibres non-septate.

Axial parenchyma. Axial parenchyma banded or not banded. Axial parenchyma bands marginal (or seemingly marginal), bands much wider than rays, coarse, more than three cells wide (intial parenchyma as wide as the earlywood pore ring). Axial parenchyma paratracheal. Paratracheal axial parenchyma vasicentric, or aliform, or confluent (latewood vessles only). Aliform parenchyma lozenge and winged. Axial parenchyma as strands. Average number of cells per axial parenchyma strand 2–5.

Rays. Rays 3–6 per tangential mm, multiseriate, also if only few, 2–5 cells wide, 2–3 cells wide to commonly 3–5 cells wide. Height of large rays up to 500 µm. Rays composed of a single cell type, or two or more cell types. Homocellular ray cells procumbent. Heterocellular rays square and upright cells restricted to marginal rows. Number of marginal rows of upright or square cells 1.

Storied structures. Storied structure absent.

Secretory structures. Intercellular canals absent. Laticifers or tanniniferous tubes absent.

Cambial variants. Included phloem absent. Other cambial variants absent.

Mineral inclusions. Crystals not observed. Silica not observed.

Physical and chemical tests. Heartwood not fluorescent.


Cite this publication as: H. G. Richter and M. J. Dallwitz (2000 onwards). 'Commercial timbers: descriptions, illustrations, identification, and information retrieval.' In English, French, German, and Spanish. Version: 4th May 2000. http://biodiversity.uno.edu/delta/.

Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993 onwards, 1995 onwards, 1998) should also be cited (see General references).

Index