AOBPreview originally published online on March 31, 2005
Annals of Botany 2005 95(7):1179-1186; doi:10.1093/aob/mci130
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Biomechanical Model of the Xylem Vessels in Vascular Plants
Lebanese American University, Byblos, PO Box 166864, Beirut, Lebanon
* For correspondence. E-mail gkaram{at}lau.edu.lb
Received: 17 January 2004 Returned for revision: 1 July 2004 Accepted: 14 February 2005 Published electronically: 31 March 2005
• Background and Aims The xylem, or water transport system, in vascular plants adopts different morphologies that appear sequentially during growth phases. This paper proposes an explanation of these morphologies based on engineering design principles.
• Methods Using microscopic observations of the different growth stages, an engineering analysis of the xylem vessels as a closed cylinder under internal pressure is carried out adopting pressure vessel design concepts.
• Key Results The analysis suggests that the xylem vessel structural morphology follows the ‘constant strength’ design principle, i.e. all of the material within the wall of the xylem is loaded equally to its maximum allowable stress capacity, and the amount of material used is therefore systematically minimized. The analysis shows that the different structural designs of the xylem vessel walls (annular, helical, reticulate and pitted) all quantitatively follow the constant strength design principle.
• Conclusions The results are discussed with respect to growth and differentiation. It is concluded that the morphology of the xylem vessel through the different phases of growth seems to follow optimal engineering design principles.
Key words: Xylem vessel, vascular plant, constant strength, structural design, xylem cell wall, biomechanics