The phytolith morphotypes of six species genus Stipa growing in the south of Western Siberia: S. sapillata, S. korshinski, S. pennata, S. dasyphylla, S. lessingiana, S. zalesskii are presented in the article after the microscopic examination of the digested herbarium material. The investigated shapes of phytoliths were divided by frequency of occurrence in different species of the genus into three groups. The morphotypes of phytoliths, which are similar in all studied species, have been identified (truncated conical and rounded particles, trapezoidal short particles, special forms of trichomes). They can serve as the diagnostic forms for different arid grassland ecosystems. The differences in feather-grass trichomes from the similar shapes of mesophilic gramineous plants and their frequency of occurrence in some species genus Stipa have been revealed during the investigation. Shapes that characterize a group of cirrus feather-grass have been identified. Previously not studied morphotype — trapezoidal papillary particles has been detected in Stipa capillata. The assignment of trapezoidal corrugated and elongated particles to one morphotype have been proved.