Testing the Reliability of Anatomical and Epidermical Characters in Grass Taxonomy

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 [1]. Such characters became well-established and accepted in the 1960s with Metcalfe’s investigations [2]. 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 [4]. 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. Three accessions for each species and for each habitat were investigated. Leaf blades were treated following our modified versions of the methods described by Dop & Gautié [5] and Halbritter [6]. SEM observations were under a JEOL JSM T220. Analysis of structures was standardized [7, 8]. A number of leaf characters proved to be plastic. Density of exodermic elements is higher (Figure 1. A-B) and sclerenchyma more developed in the driest habitats. Bulliform cells are far more developed in Antinoria growing in dry conditions than in submerged plants; in Corynephoru