The evolutionary importance of horizontal gene transfer is increasingly ackonwledged, In the genus Hordeum (Triticeae, Pooideae), we revealed a spectacular diversity of foreign rDNA (ribotypes) corresponding to paniocid grasses. They were likely acquired through several independent horizonatal tranfers. We found that foreign rDNA together with LTR-retrotransposons was transferred from Panicum to H. bogdanii. Within this project we are investigating the nature and dynamics of foreign genetic material in Hordeum with a focus on multiple foreign rDNA. Hordeum stenostachys, possesing five different foreign ribotypes in its genome, serves as a model species. The investigation of H. stenostachys and related Hordeum species using molecular, bioinformatic an cytogenetic approaches allows us to unlock the nature and evolutionary consequences of multiple integration of foreign DNA.