Stomata are small pores on the plant leaves that participate in the gas exchange process.

These pores are constructed from a pair of guardian cells, which open and close frequently, thus requiring an extremely strong and flexible structure. Cellulose (arranged in rod-like microfibrils) is the main cell wall polymer - conferring support and rigidity upon the plant cell.
In a study conducted by Dr Ilana Shtein and Dr Smadar Harpaz-Saad, from The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem,stomatal cell wall structure was examined in a broad structural and evolutionary spectrum of plants - ferns, angiosperms, and grasses. In the study they utilized computerized polarized light microscopy (PolScope) and confocal microscopy. Plants samples were collected from the TAU Botanical Garden, and the pictures seen here represent stoma of an elkhorn fern (Platycerium bifurcatum), growing in the tropical house. The results of this study have demonstrated for the first time the existence of distinct spatial patterns of varying cellulose crystallinity in guard cell walls. These differences may reflect modifications to the stomatal complex that occurred in response to specific environmental challenges and that have allowed the stomata to retain their distinctive structure without compromising their function. This study is about to be published in the journal ‘Annals of Botany’.