Abies concolor (the white fir) and Abies grandis (the grand fir) are closely related species which readily form hybrids. Whereas the primary range of A. concolor is south of the California-Oregon border, and A. grandis ranges along the coast and north of the border, a putative hybrid zone has been identified in Southern Oregon. Because these species are so closely related, the present study attempts to identify distinctive genetic characteristics by sequencing non-coding regions of the genome known as "Short Sequence Repeats" (SSRs) or "microsatellites". As microsatellites tend to be highly polymorphic, they can often be used to differentiate closely-related populations. The goal of the present study is to identify microsatellite genotypes specific to each "pure" population; so as to later determine the contribution of each to the gene pool of the hybrid population.