Vanilla orchids (Nigritella) are taxonomically and morphologically difficult genus in the orchid family, within which only three species were known in Slovenia for a long time. In recent years, some authors have confirmed at least three additional species. In the study, we therefore sought to find populations of all known taxa in Slovenian Alps and to study the differences in their morphology and patterns of their distribution. We identified 57 characters (22 macromorphological characters, 21 flower characters, 2 micromorphological characters and 12 derived numerical characters) and measured them on 186 plants collected in the field. The data was then processed statistically, using the box plot diagrams, 100% loaded column charts, main component analysis (PCA), and main coordinate analysis (PCoA). On the basis of the obtained results, we produced descriptions and distribution maps of individual taxa and a dichotomous key for determining species from the genus Nigritella in Slovenia. Through our research, we have confirmed the presence of seven taxa in Slovenian Alps. At the same time, we found out that the combination of the lower and upper flowers in the inflorescence is the most important character for separating the taxa in the initial phase of determination. In later stages of determination, however, the most useful are the flower characters and the length of the pollen grains. The latter also proved to be an important indicator in the indirect assessment of ploid state of vanilla orchids in Slovenia.
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