Species of the genus Lophopyrum are closely related to the genus Triticum and have been extensively used in wheat breeding. To facilitate the detection of the Lophopyrum chromatin in wheat, two repeated nucleotide sequences were isolated from L. elongatum (Host) Lve (= Agropyron elongatum Host, Elytrigia elongata (Host) Nevski), which hybridized strongly with the DNAs of Lophopyrum species but weakly (pLeUCD1) or essentially not at all (pLeUCD2) with those of Triticum species. Both sequences were shown to be on all chromosomes of L. elongatum. Each chromosome arm of L. elongatum showed a unique pattern of restriction fragments hybridizing with pLeUCD2. The analysis of chromosomes recombinant between chromosome arm 3AgL of L. ponticum (Podp.) Lve and chromosome arm 3DL of wheat (T. aestivum L.) showed that regional heterogeneity of the pLeUCD2 family occurs also within the arm. It was demonstrated that this heterogeneity can be exploited for identification of Lophopyrum chromatin in wheat and mapping of crossover points in Lophopyrumwheat recombinant chromosomes by Southern blot analysis.Key words: concerted evolution, Triticum, gene transfer.