Optimal vein density in artificial and real leaves


Noblin, X. ; Mahadevan, L. ; Coomaraswamy, I. A. ; Weitz, D. A. ; Holbrook, N. M. ; Zwieniecki, M. A. Optimal vein density in artificial and real leaves. Proceedings of the National Academy of Sciences of the United States of America 2008, 105, 9140-9144. Copy at http://www.tinyurl.com/lybw5pg
2008_pnas_noblin.pdf375 KB


The long evolution of vascular plants has resulted in a tremendous variety of natural networks responsible for the evaporatively driven transport of water. Nevertheless, little is known about the physical principles that constrain vascular architecture. Inspired by plant leaves, we used microfluidic devices consisting of simple parallel channel networks in a polymeric material layer, permeable to water, to study the mechanisms of and the limits to evaporation-driven flow. We show that the flow rate through our biomimetic leaves increases linearly with channel density (1/d) until the distance between channels (d) is comparable with the thickness of the polymer layer (5), above which the flow rate saturates. A comparison with the plant vascular networks shows that the same optimization criterion can be used to describe the placement of veins in leaves. These scaling relations for evaporatively driven flow through simple networks reveal basic design principles for the engineering of evaporation-permeation-driven devices, and highlight the role of physical constraints on the biological design or leaves.


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Last updated on 04/09/2014