EFFECT OF THE PERISTOMATAL RIM UPON STOMATAL MOVEMENTS IN <i>POPULUS MEXICANA</i> (SALICACEAE)

Abstract

Light and scanning electron microscopy were used to study the stomatal complexes of Populus mexicana, which has xeromorphic leaf structure. In this poplar, the stomatal complexes are laterocytic and paracytic. The subsidiary cell walls form the peristomatal rim, which rests upon the outer tangential walls of the guard cells. To elucidate the function of the peristomatal rim, we applied modelling using the finite element method. The modelling has shown that the inner and the outer tangential walls of the guard cells bend outward when the stoma is opening. The peristomatal rim hinders the movements of the outer tangential walls of the guard cells. Due to the peristomatal rim, the open stomatal pore sinks deeper into the epidermis. It is narrower and better covered with the outer stomatal ledges, than the one in the stomatal complex without peristomatal rim. The probability of influence of stomatal mechanics in P. mexicana upon water losses during transpiration is under discussion.