Morphological variability of Helleborines. I. Diagnostic significance of morphological features in Epipactis helleborine (L.) Crantz, Epipactis atrorubens (Hoffm.) Besser and their hybrid, Epipactis ×schmalhausenii Richt. (Orchidaceae, Neottieae)

Abstract

The comparative analysis of leaf morphology was performed in E. helleborine (L.) Crantz, E.atrorubens (Hoffm.) Besser, and their interspecific hybrid, Epipactis ×schmalhausenii Richt. The aim of this research was to find out features that would be useful in the taxonomy of the genus Epipactis, and particulary their taxa of hybrid origin. In course of the studies special attention was paid to leaf morphology, mostly to their margins, presence of papillae, their shape and size, and to leaf structure. The thickness of the leaf blades manifested by number of spongy mesophyll cell layers, size of vascular bundles and the level of leaf sclerification were compared in the hybrid and both parental species. In E. helleborine and E. atrorubens the analyzed features were highly variable, especially in the former species, which is characterized by wide phenotypic plasticity. Morphological and anatomical features in E. ×schmalhausenii showed a transitional character to the parental species. Our results suggest that a single feature can not be of taxonomic value, but the combination of different traits has to be considered when distinguishing parental and hybrid taxa.