Leaf venation density as a climate and environmental proxy: a critical review and new data

Evolution of C 4 plants: a new hypothesis for an interaction of CO 2 and water relations mediated by plant hydraulics

“…Previous studies of adaptation to these conditions within species or across closely related species within given lineages have shown increased vein densities, and thus shorter interveinal distances [76][77][78][79]. This higher vein density would permit greater g s and higher A during periods with high water availability, to compensate for low CO 2 .…”

Developmentally based scaling of leaf venation architecture explains global ecological patterns

“…Thus, it would be possible to achieve higher final minor vein density in a smaller leaf by limiting leaf expansion after all veins are formed; or higher final minor vein density without change in leaf size by compensating with increasing expansion before the final vein order is formed; or higher final minor vein density with a larger leaf, with still greater expansion before the final vein order is formed; or a larger leaf without change in minor vein density by increasing expansion only before the final vein order is formed, thus initiating veins in the same proportion to leaf area as in the small leaf. All of these scenarios can occur, for example, for the sun relative to shade leaves of given species, and across populations or across closely related species adapted across habitats 4,12,[30][31][32][33][34][35][36][37] . Notably, leaf expansion relative to vein formation can be influenced by modulating cell proliferation, which especially affects expansion before the final vein order is formed, and final cell size, which mainly affects expansion after all veins are formed 38,39 .…”

Viewing leaf structure and evolution from a hydraulic perspective

“…In this latter respect there is considerable potential for using fossil leaf vein characteristics as a tool for reconstructing atmospheric conditions over geological time. Similar to stomatal indices, leaf veins provide insight into the gas exchange characteristics of leaves as well as potentially indicating atmospheric humidity and CO 2 concentrations (Uhl and Mosbrugger 1999;Brodribb and Feild 2010). Recent work has demonstrated that leaf veins may in fact be a more sensitive measure of the leaf physiology than stomatal characters, due to the complex influence of stomatal and cuticular architecture upon actual versus modelled gas-exchange rates in leaves (T. S. Feild, D. Chatelet and T. J.…”