Plant Hydraulic Architecture through Geological time

The study of wood is key to the understanding of water transport and water relationships in trees, shrubs and climbers, and to the responses of these plants to climate change. In turn, the study of fossil wood is key to understanding the evolution of cells and tissues functioning in water conduction, mechanical strength, and storage and biological defence in woody plants.

In nine individual papers, this special issue of the IAWA Journal brings together information on fossil xylem from the earliest woody plants in the Devonian (420–360 Ma) to more recent woody floras from the Cenozoic, compared against the backdrop of the extant woody flora. Most papers were developed from presentations at the IAWA Symposium “Hydraulic Architecture through Time” held during the International Paleobotany Congress in Salvador de Bahia, Brazil, in October 2016. Others were invited at a later date. All papers take into account the latest insights in xylem evolution and the role of wood in tree biology and ecosystem functioning. Several woody form genera and species are named and described for the first time.

This book is aimed at researchers and students of paleobotany, plant evolution, wood anatomy, ecology, and climate change.


by an IAWA Committee of 16 bark anatomists
and edited by
Veronica Angyalossy, Marcelo R. Pace, and Pieter Baas
Reprinted from IAWA Journal 37(4): 517–615 (2016)
Price of hard copies in special cover (paperback): EUR 13.00 (USD 15.00) plus postage. Special discounts will be given for bulk orders for teaching purposes.
This IAWA List of microscopic bark characters sets a new international standard for the definition and recognition of anatomical features of barks in woody angiosperms and gymnosperms. Codes are given for 173 anatomical character states to facilitate databasing the huge diversity of bark structure in trees and shrubs. It is richly illustrated with 169 splendid micrographs, virtually all in colour. An appendix gives practical guidance on methods for the microscopic study of bark.
The “IAWA Bark List” is not only indispensable for any future work on comparative bark anatomy and microscopic bark identification, but can also be used as a first inventory of functional traits in this complex tissue that is so vital for the physiology and protection of trees. Its significance can be compared with the IAWA Lists for Hardwood and Softwood Identification (1989 and 2004) that have been adopted by the entire international wood anatomical community.
The Bark List will also be a most valuable resource for advanced botanical teaching.

Functional Traits in Wood Anatomy

edited by
Pieter Baas, Hans Beeckman,
Katarina Čufar, Veronica De Micco
Reprinted from IAWA Journal 37 (2), 2016: 121-368. ISSN 0928-1541
International Association of Wood Anatomists c/o Naturalis Biodiversity Center
Price: EUR 25.00 or US$ 30.00 plus postage and handling
Please order directly from the IAWA Office: or
Natural and plantation forests, park and roadside trees, and even arctic, alpine and desert shrubs all depend on their wood or secondary xylem for hydraulic and mechanical fitness and biological defence. In recent decades the research community has become aware that the complex tissue of wood harbours a wealth of so-called functional traits that make natural and manmade ecosystems dynamic and sustainable. On the other hand, natural and anthropogenic stress factors such as prolonged or extreme droughts, floods, hurricanes and snow storms, which seem on the increase in our globally warming era, challenge the limits of functional xylem and phloem adaptations arisen over millions of years of adaptive evolution.

This special issue of the IAWA Journal brings together 12 papers by researchers collaborating in the Functional Traits Topic Group of the Cost-Action STReESS (Studying Tree Responses to extreme Events: a Synthesis) that was active from 2012 to 2016. Six papers are reviews of the literature dealing with the concept of functional traits in wood anatomy, and with individual functional traits such as porosity, various other growth ring markers, intra-annual density fluctuations (IADFs), inter-conduit pit membranes, vessel occlusions, and onset of sap conduction in earlywood vessels.

The other six papers contain a wealth of original results ranging from cambium dynamics and phloem formation to growth ring and IADF analysis in European and Tropical forests exposed at increasing frequency to extreme events. This book is aimed at the research community and advanced students of plant biology, forestry, wood science, and global change.

Also available:

Wood Structure in Plant Biology and Ecology

edited by
Pieter Baas, Giovanna Battipaglia,
Veronica De Micco, Frederic Lens, Elisabeth Wheeler
Reprinted from IAWA Journal 34 (4), 2013, 181 pp.
Price: EUR 20.00 (US$ 25.00) plus postage and handling

Beauty in wood by Steven Jansen, Peter Gasson, and E. A. Wheeler, Lulu, 2010.
31 pages ; incl. color illustrations ; 28 cm
Beauty in Wood is a photobook with contributions from over 30 wood scientists. The images showing the beauty in wood as viewed at different scales -- from attractive grain patterns visible at the macroscopic level to light microscope views of patterns of systematic value to electron microscope views of the minute features important to water movement in trees. Over 30 wood anatomists contributed photos. A few select references provide additional information on the topics illustrated.
The book is available for sale through Lulu Press, with profits going to IAWA. To buy this wonderful photobook, please visit
The following publications are available from the IAWA Office:

IAWA Journal Supplements
  • WHEELER, E.A. & T.A. DILLHOFF. 2009. The Middle Miocene Wood Flora of Vantage, Washington, USA. IAWA Journal Supplement 7. 101 pp. ISBN 978-90-71236-69-3. EUR 20.00 or USD 25.00 (IAWA members EUR 13.00 or USD 15.00).
  • GREGORY, M., I. POOLE & E.A. WHEELER. 2009. Fossil dicot wood names - an annotated list with full bibliography. IAWA Journal Supplement 6. 220 pp. ISBN 90-71236-68-6. EUR 35.00 or USD 40.00 (IAWA members EUR/USD 20.00).
  • EVANS, J.A., P.E. GASSON & G.P. LEWIS. 2006. Wood anatomy of the Mimosoideae (Leguminosae). IAWA Journal Supplement 5. 118 pp. ISBN 90-71236-63-3. EUR/USD 20.00.
  • WESTRA, L.Y.TH. & J. KOEK-NOORMAN. 2004. Wood Atlas of the Euphorbiaceae s.l. IAWA Journal Supplement 4. 110 pp. ISBN 90-71236-60-9. EUR/USD 20.00.
  • WHEELER, E.A. & S.R. MANCHESTER. 2002. Woods of the Eocene Nut Beds Flora, Clarno Formation, Oregon, USA. IAWA Journal Supplement 3. 188 pp. ISBN 90-71236-52-8. EUR 35.00 or USD 40.00 (IAWA members EUR/USD 30.00).
  • KLAASSEN, R. 1999. Wood anatomy of the Sapindaceae. IAWA Journal Supplement 2. 219 pp. ISBN 90-71236-40-4. EUR 35.00 or USD 40.00.
  • GREGORY, M. 1994. Bibliography of systematic wood anatomy of dicotyledons. IAWA Journal Supplement 1. 265 pp. ISBN 90-71236-22-6. EUR 35.00 or USD 40.00 (IAWA members EUR/USD 25.00).
IAWA list of microscopic features for softwood/hardwood identification
  • IAWA COMMITTEE (H.G. RICHTER, D. GROSSER, I. HEINZ & P.E. GASSON, Eds). 2004. IAWA list of microscopic features for softwood identification. Repr. IAWA Journal 25: 1-70. EUR 25.00 or USD 30.00.
  • IAWA COMMITTEE (E.A. WHEELER, P. BAAS & P. GASSON, Eds). 1989. IAWA list of microscopic features for hardwood identification. Repr. IAWA Journal 10: 219-332. EUR 25.00 or USD 35.00.
Other Publications
  • BAAS, P., G. BATTIPAGLIA, V. DE MICCO, F. LENS & E. WHEELER (Eds). 2013. Wood Structure in Plant Biology and Ecology. Repr. IAWA Journal 34 (4). EUR 30.00 or USD 35.00.
  • WIEDENHOEFT, A.C. & P. BAAS (Eds). 2011. Wood science for promoting legal timber harvest (incl. a microscopic atlas of all Cites-listed tree species). Repr. IAWA Journal 32 (2). EUR 25.00 or USD 30.00.
  • ECKSTEIN, D. & P. BAAS (Eds). 1999. Dendrochronology in monsoon Asia. Repr. IAWA Journal 20 (3). EUR/USD 15.00.
  • ECKSTEIN, D., U. SASS & P. BAAS (Eds). 1995. Growth periodicity in tropical trees. Repr. IAWA Journal 16 (4): 323-442. EUR/USD 15.00.
Back issues of IAWA Bulletin/Journal
Availability and prices upon request from:
Ingrid de Kort, email:
IAWA Office, Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, The Netherlands
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