The taxonomic and phylogenetic utility of vegetative anatomy and fruit epidermal silica bodies in Carex section Phyllostachys (Cyperaceae)

Abstract

In Carex, vegetative anatomy and fruit epidermal silica bodies have been used to delimit species and sections, although frequent conflicts with traditional classifications have led many authors to question whether they can be used to infer evolutionary relationships. This conclusion, however, has largely been drawn from poorly circumscribed groups that have not been phylogenetically analyzed. This study was undertaken to assess the taxonomic and phylogenetic utility of these characters within Carex section Phyllostachys, a small (eight species), monophyletic group whose taxonomy and phylogeny has been extensively studied. Leaf and culm anatomy clearly separate the close species pair of Carex backii Boott and Carex saximontana Mackenzie, and they provide unique characters that distinguish Carex latebracteata Waterfall and Carex juniperorum Catling, Reznicek, & Crins. Anatomical and silica body characters strongly support the recognition of three species within the Carex willdenowii Willdenow complex (Carex willdenowii s.s., Carex basiantha Steudel, Carex superata Naczi, Reznicek, & B.A. Ford). Although unique characters were lacking in Carex jamesii Schw., infraspecific variation in its silica bodies was consistent with the high levels of genetic and morphological variation previously detected. Silica body characters support groups that are congruent with previous phylogenetic hypotheses derived from both morphological and molecular data. In contrast, vegetative anatomy, in this and previous studies, supports contradictory groups suggesting that its use in future phylogenetic studies below the sectional level in Carex may be limited.Key words: Carex, anatomy, silica bodies, cladistics, species circumscription.