Shapes of leaves with parallel venation. Modelling of theEpipactissp. (Orchidaceae) leaves with the help of a system of coupled elastic beams

Static properties of leaves with parallel venation, with particular emphasis on the genus Epipactis Zinn, 1757 (Orchidaceae, Neottieae) have been modelled with coupled quasi-parallel elastic “beams.” The non-linear theory of strongly bended beams have been employed. The resulting boundary-value problem has been solved numerically with the help of the finite-difference method. Possible dislocations resulting in additional Dirac-delta like forces have been take into account. Morphological similarity of the model and real leaves has been obtained. In particular, the concentrated forces have been shown to cause undulation in the leaves.