Chromosome number, meiotic behavior and morphological characters related to habit and pollen grains were studied in Onobrychis bojnurdensis Ranjbar & Hajmoradi as a new species belonging to Onobrychis sect. Hymenobrychis from East of Iran. The new species is related to O. sintenisii but differs from it in a few morphological characters such as plant indumentums, size of stipule, bract and different part of the flower. We evaluated and determined the species limits within Eastern species of O. sect. Hymenobrychis, employing multivariate statistics. Results obtained from morphological and micromorphological studies confirm novelty of O. bojnurdensis. Cytogenetic study indicates that the O. bojnurdensis is a diploid plant and possesses 2n = 2x = 14 chromosome number. The general meiotic behavior was regular, with bivalent pairing and normal chromosome segregation at meiosis. This report is the first cytogenetic analysis of the new taxon.
