SEM analysis of Utah Equisetum stems (Equisetaceae)

The Utah taxa of Equisetum were observed with the scanning electron microscope to test for taxonomic significance of stem morphology. The four Utah species of Equisetum were compared. Stem morphology was shown to be taxonomically significant in most cases. The hybrid E. x ferrissii , recognized in the literature as being extant in Utah but heretofore unrecognized in Utah herbaria, was shown to be present in the flora of the state.