Silene petersonii

Holmgren et al. (2012) recognize Silene petersonii and S. clokeyi as distinct species with distinct morphological traits. Kartesz (1994, 1999) also recognized S. petersonii and S. clokeyi as distinct species. In contrast, Flora of North America Editorial Committee (2005) synonymizes S. clokeyi with S. petersonii based on interfertility. Regarding the distinction of varieties within S. petersonii, Holmgren et al. (2012) maintain var. minor, but Welsh et al. (2015) state "there is a complete transition with the typical material". Welsh et al. (2015) do not recognize varieties in S. petersonii. Flora of North America Editorial Committee (2005) also synonymizes S. petersonii var. minor.

Silene petersonii is a perennial forb which is endemic to Flagstaff and Claron Formation limestones in central and southwestern Utah. Silene petersonii occurs in Sanpete, Sevier, Garfield, Iron and Kane counties. It is known from approximately 45 occurrences, which are threatened by road construction and maintenance, sheep trampling, recreation, mineral exploration, and (potentially) over-collection. Several occurrences are in National Park Service units (Bryce Canyon, Cedar Breaks). Protected sites also include Red Canyon Research Natural Area (Dixie National Forest) and designated critical habitat for another co-occurring plant species (Astragalus montii), which is Federally Threatened.

Silene petersonii occurs in the western United States, where it is endemic to central and southwestern Utah (in Sanpete, Sevier, Garfield, Iron and Kane counties) (Welsh et al. 2015). The Flora of North America Committee synonymizes S. petersonii and S. clokeyi and reports this species from Nevada (FNA 2005), but Welsh et al. (2015) and Holmgren et al. (2012) consider this taxon to be endemic to Utah. Range extent was calculated using data from the Utah Rare Plant Database (2023), excluding historical observations over 40 years old (UNHP 2023).

By applying a 2 km separation distance to population location data from the Utah Rare Plant Database (2023), there are 45 estimated occurrences, excluding historical observations over 40 years old (UNHP 2023). According to the Utah Rare Plant Master List (UNPS 2025), populations are numerous, which may reflect a high rate of collection.

Threats to Silene petersonii include the expansion and maintenance of the Skyline roadway, trampling by sheep, possibly recreation, and mineral exploration (R. Fitts, pers. comm., 2015). Because the plant grows along the upper rim of plateaus, it is also thought that climate change is a threat. This species is showy and there are numerous records known, which may indicate that this species is at risk of botanical over-collection (UNPS 2025).