Primula utahensis

When Dodecatheon dentatum var. utahense was described, Holmgren (1994) stated "This new variety represents a geographic stepping stone between D. dentatum var. dentatum of the Pacific Northwest and D. dentatum var. ellisiae of the Southwest. Rationale for using the infraspecific rank of variety includes historical precedence and preponderant usage, convenience of grouping multiple varieties into subspecies, and elimination of subjectivity in grading the magnitude of genetic differences." Kartesz (1999) recognized this taxon at the subspecies level. FNA (vol. 8, 2009) elevates D. dentatum ssp. utahense to full species as D. utahense and Mast and Reveal (2007) transfer it to Primula utahensis.

Primula utahensis is a perennial forb endemic to moist habitats in the cracks and crevices of limestone and quartz outcrops near seeps or flowing water in Big and Little Cottonwood Canyons of the central Wasatch Mountain Range in Salt Lake County, Utah. There are three estimated occurrences of this species, which are threatened by impacts from hikers and by climate change and drought, though most occurrences are in remote locations of the Wasatch-Cache National Forest. Primula utahensis has a very restricted range of approximately 13 square kilometers and is narrowly restricted in habitat to rocky outcrops in seeps and wet places.

Primula utahensis occurs in western North America, where it is restricted to Big and Little Cottonwood Canyons of the central Wasatch Mountain Range in Salt Lake County, Utah (Franklin 2005, UNHP 2024). Range extent was calculated using data from the Utah Rare Plant Database (2024), excluding historical observations over 40 years old (UNHP 2024).

By applying a 2 km separation distance to population location data from the Utah Rare Plant Database (2024), there are three estimated occurrences (UNHP 2024). Primula utahensis was originally known from five general areas of Big Cottonwood Canyon in the central Wasatch Mountain Range: Mule Hollow, Mill B North Fork, Elbow Fork, and Mill B South Fork (Franklin 2005). Subsequent surveys have located ten new localities in Little Cottonwood Canyon since 2007 (UNHP 2024).

The majority of Primula utahensis occurrences are fairly isolated and face few direct threats (Franklin 2005). However, populations at Moss Ledge Picnic Area and along the canyon to Moss Falls have seen declines in their health due to compaction of the soils and direct damage to plants caused by hikers. This picnic area might be closed for other reasons which would open up the possibility for site rehabilitation (Franklin 2005). Climate change and drought may alter habitat conditions and/or dry up seeps upon which this species depends (UNHP 2024).