In this study, both morphological characters and molecular techniques were used to determine the taxonomic position of the local endemic Agropyron deweyi within the genus. Plant length, inflorescence type, flower, leaf, spike, spikelet, indumentum and lemma structures were studied as morphological characters. DNA sequences of the nuclear ribosomal DNA internal transcribed spacer region (nrDNA ITS) and four chloroplast DNA regions [trnT-trnL intergenic spacer (IGS), trnL intron, trnL-trnF IGS and matK gene] were analyzed as part of molecular investigations. The results demonstrated that no remarkable morphological differences exist among studied specimens of A. deweyi and A. cristatum complex. Based on 12 sequences of 4 Agropyron taxa produced from the current study and different numbers of sequences obtained from GenBank, our results support the conclusion that the taxonomic status of Agropyron deweyi is synonymous to that of the species A. cristatum. Sequence divergences were estimated using Kimura two-parameter model, and the phylogenetic analyses were performed using the maximum parsimony (MP) and maximum likelihood (ML) methods. No genetic variation was observed among samples of native A. deweyi and A. cristatum complex regardless of the analyzed region. Agropyron deweyi was especially very similar to A. cristatum subsp. pectinatum var. pectinatum in terms of morphological characters such as inflorescence rachis tough at maturity, spikelets with distinct gaps, indumentum glabrous, and lemma glabrous. Therefore, when all morphological and molecular results are taken into account, A. deweyi and A. cristatum subsp. pectinatum var. pectinatum should be considered as synonym.