The importance of leaf cuticle for carbon economy and  mechanical strength.
Cuticle thickness of leaves varies > 100 times across species, yet its dry mass cost and ecological benefits are poorly understood. It has been repeatedly demonstrated that thicker cuticle is not superior as a water barrier, implying that other functions must be important. Here, we measured the mechanical properties, dry mass and density of isolated cuticle from 13 evergreen woody species of Australian forests. Summed adaxial and abaxial cuticle membrane mass per unit leaf area (CMA) varied from 2.95 to 27.4 g m(-2)  across species, and accounted for 6.7-24% of lamina dry mass. Density of cuticle varied only from 1.04 to 1.24 g cm(-3) ; thus variation in CMA was mostly due to variation in cuticle thickness. Thicker cuticle was more resistant to tearing. Tensile strength and modulus of elasticity of cuticle were much higher than those of leaf laminas, with significant differences between adaxial and abaxial cuticles. While cuticle membranes were thin, they could account for a significant fraction of leaf dry mass due to their high density. The substantial cost of thicker cuticle is probably offset by increased mechanical resistance which might confer longer leaf lifespans among evergreen species.
Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia.|Division of Environmental Science and Technology, Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502, Japan.
Yusuke
Y
Onoda
Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia.|Biology Department, University of Nevada Reno, Reno, NV, 89557, USA.
Lora
L
Richards
Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia.
Mark
M
Westoby
D001696:Biomechanical Phenomena / Q000502:physiology; D002244:Carbon / Q000378:metabolism*; D008566:Membranes; D019441:Plant Epidermis / Q000033:anatomy & histology / Q000502:physiology*; D018515:Plant Leaves / Q000033:anatomy & histology / Q000502:physiology*; D013718:Tensile Strength / Q000502:physiology; D014197:Trees / Q000033:anatomy & histology / Q000502:physiology
D002244:Carbon