Beyond the typological characters: A morphometric approach to vegetative characters in Anthurium Schott (Araceae) species

Most plant descriptions focus on differences in reproductive structures, but some lineages, including the genus Anthurium Schott (Araceae), have the vegetative characters as the main source of relevant taxonomic variability. Several herbarium specimens of Anthurium have inaccurate determinations due to the great leaf-blade plasticity conflicting with the typical shape described. To address how much variation exist in natural populations and how the typical shape of the leaf-blade is distributed in these populations, we examine a representative set of samples from the type locality of six species of Anthurium Schott sect. Urospadix Engl. subsect. Obscureviridia Engl. from the Atlantic Forest through the elliptic Fourier analysis (EFA). We performed a EFA to quantify the leaf-blade shape amplitude, along with a qualitative classification matrix. The data were submitted to a multivariate set of methods to confront boundaries between character states and the degree of identification efficiency of each species. Our study is the first to present the proportion in which morphotypes may be distributed in natural populations and the results can help interpret doubtful materials in herbarium collections. Our data demonstrated that each dataset has a distinct morphological signature represented mainly by the mean shape, which may differ from the shape originally described in the protologue. We suggest a criterion to be adopted to improve this character’s effectiveness and use in taxonomic comparisons, which can also be adapted for other laminar structures.