Grasses are simplified plants and the leaf is one of the few organs that provides taxonomic characters. Leaf anatomy and epidermis (and associated structures) have been used as characters in taxonomy of Poaceae since the 1930s. Such characters became well-established and accepted in the 1960s with Metcalfe's investigations. However, recent research casts doubts on the consistency and reliability of such characters [e.g. 3]. Grasses are highly adaptable plants due to their marked phenotypic plasticity. In order to assess the reliability of leaf characters, species that occur in very contrasting habitats constitute the ideal case study. Corynephorus canescens (L.) P. Beauv. and Antinoria agrostidea (DC.) Parl. were selected; the former occurs from coastal sandy dunes to high altitude, the latter survives submerged and in ponds that dry-out during summer.