Structural features of leaf epidermis Saussurea pulchella (Fisch.) Fisch. and S. neopulchella Lipsch

The leaf epidermis of taxonomically difficult Far East species of Saussurea pulchella and S. neopulchella were studied. The results of the morphometric analysis of the epidermal cells and stoma are presented. A comparative research of the epidermal cells and stoma of the leaf of S. pulchella and S. neopulchella allowed revealing constant parameters at the level of the genus: they are the form of around stomata and epidermal cells, the type and the form of stoma and trichomes. For both species of plants, the stomata of anomocytic type are characteristic. The stomata are of elongated and roundish form and they are surrounded by 3-7 cells. The size, the amplitude and the frequency of waves of around stomata cells correspond to the parameters of the epidermal cells. The form and the size of cells adjoining the guard cells do not differ from the epidermal cells. A certain orientation of around stomata cells is not observed. The epidermal cells are of a polygonal or wrong form with rectilinearly-roundish or twisting outlines. The projection of epidermal cells is polygonal, roundish or spread. Both species of plants have single-row multicellular simple trichomes on the upper and the lower surface of the leaf. They are formed by cells of a cubical form with the extended apical cell. In the basis of the trichome, there is a cell of a roundish form which is surrounded by polygonal epidermal cells dispersing in radial directions. The parameters identifying species are revealed; they are the type of the leaf, the size of the epidermal cells on the longitudinal (long) axis and the stomatal index. The leaf of S. neopulchella is hypostomatic (the stomata on the upper surface of the leaf are absent), whereas the leaf of S. pulchella is amfistomatic (the stomata are present on the upper and the lower surfaces of the leaf). The sizes of the epidermal cells on the longitudinal axis of S. neopulchella on the epidermis of the upper surface of the leaf change within the limits from 51.24 to 78.84 microns and on the epidermis of the lower surface of the leaf- from 27.93 to 56.4 microns. For S. pulchella, these indicators are within the limits from 48,89 to 84,28 microns for the epidermis of the upper surface of the leaf and from 42.52 to 82.97 microns for the epidermis of the lower surface of the leaf. The stomatal index of the species also differs: for the upper epidermis of S. neopulchella it is 0% andfor the lower epidermis - 19.93%; for the upper epidermis of S. pulchella the index is 8.48% and for the lower epidermis - 22.79%. The researched parameters of the structure of the epidermis can be used as additional diagnostic signs at identification of species.

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