Pale blue-eyed grass (Sisyrinchium sarmentosum) is a Washington State threatened species and a federal species of concern. Its current range is restricted to sites near Mt. Adams within Klickitat, Skamania, and Yakima Counties, and several sites south of Mt. Hood in Clackamas County, Oregon. It occurs within open, seasonally-wet grass and sedge meadows primarily at middle elevations. It overlaps with Sisyrinchium idahoense (Idaho blue-eyed grass) in geographic range and habitat. At several S. sarmentosum populations, individuals with characteristics somewhere between S. sarmentosum and S. idahoense have been observed, suggesting that hybridization may be occurring.
Rare Care and the US Forest Service are investigating the relationship of these two species and whether hybridization is occurring using a common garden experiment. Common garden studies bring maternal lines from different populations together in a single growing medium and environmental regimen to help determine relationships between phenotypic traits and environmental variables related to source locations (light, moisture and temperature). Information from this common garden study will be combined with genetic analyses of nuclear and chloroplast DNA to tease out the relationship between the two taxa, which was not possible using the results of DNA analyses completed by the Forest Service last year.