The Isoetes longissima complex (Isoetaceae) in Italy: observations on the morphology of spores and leaves, and taxonomic implications

Abstract

The morphological variability of the Isoetes longissima complex in Italy has been analyzed, on the basis of selected herbarium specimens. Observations were made on spore ornamentation and size, number of leaves per plant and maximum leaf length, velum extension and alae width in the basal portion of leaves. The first count of chromosome number on plants from Italy is also made. On the basis of our observations, the five taxa here considered are attributed to two taxa, treated at the species level as follows: I. longissima (incl. I. velata and I. velata [unranked] sicula), and I. tiguliana (incl. I. dubia). Italian distribution of these species is also given.