Foliar morphology and epidermal ultrastructure of four Selaginella species (Selaginellaceae–Lycophyta)

Abstract

The leaf morphology of Selaginella species from subtropical South America show differences in structure and ultrastructure that are useful for species identification. We studied the following epidermal traits: micromorphology of stomatal types, distribution patterns of silica cells, silica cells and silica bodies of Selaginella convoluta, S. microphylla, S. sellowii and S. sulcata, using light and scanning electron microscopy. Five stomatal types were observed, anomocytic, actinocytic, anisocytic, staurocytic and tetracytic and two additional variants, anomodiacytic and anomoparacytic. Five silica cell distribution patterns were identified, laminar, medial, medial-basiscopic, subcostal, and submarginal. Pyramidal silica bodies and conical bodies with concave base are described for the first time. In the studied species, silica bodies are pyramidal in S. convoluta and globular, conical and pyramidal in S. microphylla, whereas in S. sellowii and S. sulcata they are conical, with concave base of different sizes. Illustrations of the epidermal features, LM photographs, SEM micrographs and comparative tables are presented.