XVI International Botanical Congess

In maize like in most grass species, spatial colonisation relies on the self-supporting blades. In turgid leaves, the bending siffness is due mainly to the midrib and can be related to its anatomy using a composite beam model. However bending under self-weight only explained 30 % of the curvature, and most of the curvature is built in before outgrowing the enclosing sheath. When the leaf is water depleted, it rolls transversally. In maize, this rolling is poor. Using a shell model, it is shown that this low rolling is not due to anatomical peculiarities, but to a structural shell coupling with the midrib, resulting in midrib straightening. The built-in curvature is again a influential parameter of the leaf behavior. Insights on its origin inside the enclosing sheaths are given. It is argued that biomechanical model are useful tool to investigate the basis of morphologic traits.