Epidermal characteristics of the leaf in selected Valeriana species

The article presents the results of a study of leaf epidermal characters in closely related species of the genus Valeriana – Valeriana alternifolia Ledeb. Valeriana officinalis L., Valeriana wolgensis Kazak, Valeriana tuberose L., Valeriana dubia Bunge. The following were studied: leaf type based on the location of stomata on the adaxial and abaxial sides of the leaf, qualitative and quantitative characters of the leaf epidermis, the number of epidermal cells, length, width, index and shape of epidermal cells, the type of stomatal complex, the number of stomata, the length, width and index of stomatal guard cells, and the stomatal index. Stomatographic characters were studied by microscopy, types of stomatal complex were determined according to the method of M.A. Baranova (1985). The index of epidermal cells and stomatal guard cells was calculated as the ratio of the width to their length. It was established that the leaf type of V. alternifolia and V. officinalis is the same – hypostomate, i.e. the stomata are located only on the abaxial sides of the leaf. V. wolgensis, V. dubia and V. tuberosa are amphistomate, i.e. the stomata are present on the upper and lower surface of the leaf. It was revealed that the stomatal complex of the studied species is of the anomocytic type, the paracytic type of the stomatal complex is extremely rare. V. dubia is characterized by the presence of a greater number of epidermal cells than in the other studied species. There are no stomata on the adaxial side of the leaf of V. alternifolia and V. officinalis. The shape of the epidermal cells on the adaxial side of the leaf is sparsely sinuous (V. officinalis) or coarsely sinuous (V. alternifolia), on the abaxial side of the leaf it is frequently sinuous (V. alternifolia and V. officinalis). It is shown that the listed qualitative and quantitative characteristics of the leaf epidermis can serve as additional taxonomic characters for differentiating the closely related species V. alternifolia and V. officinalis.