A modern method, geometric morphometrics, was used to clarify
the taxonomic position of the European Ophioglossum species: O. azoricum,
O. lusitanicum, and O. vulgatum. The identification of these taxa by traditional
methods is rather difficult, due to different taxonomic interpretations. Sterile
leaf shapes were investigated using a landmark-based method and the
Fourier analysis of outlines. Both methods highlight the shape and the base of
the leaf as an important diagnostic character.
