Bromus Tectorum, commonly called cheatgrass or downy brome, is an exotic annual invasive weed that has quickly increased its range since its introduction over a hundred years ago to the western United States. Cheatgrass displaces native flora and has caused extensive loss of shrub and range habitats along with increasing wildfire frequency and devastation. Recent work in our laboratory has been dedicated to building databases of cheatgrass genotypes based on SNPs, and measure a baseline of heterozygosity for future reference. Our current study was designed to measure the actual frequency of outcrossing given conditions conducive to an outcrossing event between parents of different genotypes. Plants of different genotypes were grown together in a small plot and progeny seeds were collected at maturity. Potential heterozygotes arising from outcrossing were first identified using a panel of 4 SSR markers and subsequently validated with 96 SNP markers using the KASP (KBioscience, UK) SNP Genotyping System on a Fluidigm EP1 machine. Low levels of outcrossing were detected in this study and we are currently analyzing the data to determine if the rate of outcrossing varies between genotypes. In a second part of the study a large number of individuals were gathered from natural populations and tested using the SNP markers alone. Results show very low levels of latent heterozygosity in the wild, with significant deviations from population to population.