Technical Abstract: Within the Festuca/Lolium genome complex there is a need for rapid development of improved germplasm resources. Traditional recurrent selection methods for population or synthetic development are labor intensive and time consuming. One objective of our research is to identify novel genetic methods that would enhance traditional breeding methods and facilitate the development of improved Lolium ssp. germplasm resources. IL1 is a wide-based, diploid (2n=2x=14), early maturing ryegrass L. perenne L. subsp. aristatum Willdenow that has the ability to induce genome or chromosome loss when hybridized with other Lolium sp. IL1 was developed from a population segregating for a low level of pollen sterility. IL1 has been identified to produce dihaploid lines following interspecific Lolium x Festuca hybridizations either through chimeral sectors; or, through rare occurring seed development. The hybrids are capable of producing viable seed via genome loss and a low frequency parthenogenic response. Utilizing these materials with a complementary breeding approach may provide for the development of new and superior Lolium sp. cultivars. The release of this material will be of value to researchers of Lolium sp. breeding programs focused on developing improved germplasm.