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Diversity of tracheary elements of Aspleniaceae

Abstract

Tracheary elements can be classified as tracheids or vessel elements. In ferns, both cell types and even cells with intermediate characteristics can be observed. For a long time, the methods employed in the study of these cells were questioned and consequently their classification as well. In the present work, we analyze the stem tracheal elements of 13 Aspleniaceae species, occurring in different habitats and belonging to different clades. The samples were cut, dried on a hotplate, metallized, and analyzed in SEM. In general, the Asplenium species analyzed contain elongated conducting cells with oblique end walls, with scalariform thickening on all faces of the cell. The presence of pit membranes, however, varies greatly among species, it being possible to observe species with tracheids, with intermittent perforation plates, and with vessel elements.

Key words:
ferns; pit membrane; SEM; vessel elements; tracheids

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