Dr. Etienne Couturier presents "Fold and leaf shape" 6/11/09 at the CRI

by (newly promoted) Dr. Etienne Couturier
Laboratoire Matières et Systèmes Complexes, UMR CNRS 7057-Université Paris Diderot

We have noticed an original analogy between the leaf configuration in the bud and the paper dolls. If you fold a paper sheet and cut it with scissors, each fold will give either a sinus either a lobe when you unfold it. A lot of leaves follow this geometry in the bud. The leaf margin is folded on a plane as if it had been cut with scissor For this purely geometric reason, lobes and sinuses of the unfolded leaf exactely correspond to the initial folds. We have called these leaves "kirigami", which means fold and cut.

The purely geometric first part of this thesis shows how much the leaves geometries are constrained by their folded development. We also show that these geometries are very diverse and create very different leaves shapes. The second more biologic part proposes a mecanism for the fold development and a candidate to play the scissor role. We conclude by giving an original insight on leaf shape evolution.



You may have seen Etienne Couturier as he was starting his PhD in the film "Cherche toujours" by Mathias Théry et Etienne Chaillou (2008)... See the end of the story, live !