The leaf blade epidermis of 20 taxa of Bromus s. l. (sections Genea, Bromus, Bromopsis and Ceratochloa; tribe Bromeae) occurring in Ukraine were studied using SEM. The aim of the study was assessment of the taxonomic value of micromorphological characters and resolving some taxonomical and phylogenetical issues in the group. The main epidermal characters of leaf blades were shape, size and distribution of long cells, silica cells, crown cells, prickles, macrohairs, and cells of stomatal complexes, as well as cell wall shape, for some of them. Almost all mentioned types of cells occur on both abaxial and adaxial surfaces. The results show that crown cells were not observed in species of sect. Ceratochloa and in species B. erectus, B. benekenii, B. ramosus; prickles were not found in species of sect. Genea and some species of sect. Bromopsis. By some micromorphological characters (crown cells, prickles, and length of long cells), species of sect. Bromopsis can be subdivided into two groups. The first group consists of Bromus erectus, B. benekenii, and B. ramosus, the second one, of B. riparius, B. cappadocicus (incl. Bromopsis heterophylla, B. calcarea, B. pseudocappadocica, B. cimmerica), and the hybrid known as Bromopsis × taurica (nom. illeg.). Bromus inermis have intermediate characters. Other micromorphological features (long cells, silica cells, macrohairs and cells of stomatal complexes) in the remaining taxa were common, their variability was high. It has been found that all studied characters of the leaf blade epidermis are not specifically useful for resolution of the main taxonomic issues within tribe Bromeae. According to the conducted analysis of micromorphological features, the genus Bromus s. l. in the flora of Ukraine comprises four section-rank taxa: sect. Bromus, sect. Genea (= genus Anisantha), sect. Bromopsis, and sect. Ceratochloa.
Supplementary Material. Electronic Supplement (Table E1, p. e1) is available in the online version of this article.
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