XVI International Botanical Congess

Anatomical studies of twenty American species of Diplazium are provided to contribute to the knowledge of the genus and to ascertain its utility for the delimitation of species. Roots in all the species are diarch, rhizome is dictyostelic, petiole has two xylem strands: hippocampus shape or elliptical, in the distal petiole or in the rachis the strands are united in a single strand with rounded U or squared U shape. The cortex of the root, rhizome and stipe has starch grains. Cells with dense brown content are disposed near or around the meristeles, leaf traces, veins or medulla. The data show that the twenty species present similar anatomy, each one can be differentiated from the others by shape of the leaf trace, number of caulinar meristeles and distribution of brown content cells. The conclusions confirm the usefulness of anatomical and histochemical characters to delimitate species.