Journal of Experimental Botany, Vol. 66, No. 9 pp. 2487–2499, 2015 doi:10.1093/jxb/erv024 Advance Access publication 11 February 2015 This paper is available online free of all access charges (see http://jxb.oxfordjournals.org/open_access.html for further details) RESEARCH PAPER A novel method of measuring leaf epidermis and mesophyll stiffness shows the ubiquitous nature of the sandwich structure of leaf laminas in broad-leaved angiosperm species Yusuke Onoda1,2,*, Feike Schieving1 and Niels P. R. Anten1,3 1 Section of Plant Ecology and Biodiversity, Institute of Environmental Sciences, Utrecht University, P.O. Box 800.84, 3508TB Utrecht, The Netherlands 2 Department of Agriculture, Kyoto University, Kyoto 606-8502, Japan 3 Centre for Crop Systems Analysis, Wageningen University, P.O. Box 430, 6700AK Wageningen, The Netherlands * To whom correspondence should be addressed. E-mail:
[email protected] Received 10 November 2014; Revised 31 December 2014; Accepted 9 January 2015 Abstract Plant leaves commonly exhibit a thin, flat structure that facilitates a high light interception per unit mass, but may increase risks of mechanical failure when subjected to gravity, wind and herbivory as well as other stresses. Leaf laminas are composed of thin epidermis layers and thicker intervening mesophyll layers, which resemble a composite material, i.e. sandwich structure, used in engineering constructions (e.g. airplane wings) where high bending stiff- ness with minimum weight is important. Yet, to what extent leaf laminas are mechanically designed and behave as a sandwich structure remains unclear. To resolve this issue, we developed and applied a novel method to estimate stiffness of epidermis- and mesophyll layers without separating the layers.