Primula cusickiana var. maguirei in Utah

Logan Canyon

While heading to southern Utah just before Easter,2016, I stopped in to Logan Canyon. The entrance to this canyon lies just beyond Utah State University in the town of Logan, Utah. Scenic byway 89 follows the canyon and the Logan river that flows through this cut in the Bear River Mountains, a branch of the Wasatch Range, right through to Bear Lake. The cliffs are nearly vertical limestone and are home to Primula maguirei. At this time of year, the canyon is still very cold, particularly on the north, shaded side and icy snow lingered on the path. This Primula was just waking up, though we managed to find one plant with a single flower bud, it is obvious that this species won't bloom until much later in May. It was growing as a chasmophyte, in thin crevices in the rock and was difficult to find, being out of flower and the leaves not yet fully expanded.


Pointing out tiny P. maguirei

I was curious about this species as it is now considered a variation of P. cusickiana along with P. domensis and P. nevadensis. Certainly without referencing a key and despite the plants being in early growth their close relationship to P. cusickiana was obvious. Noel Holmgren and Sylvia Kelso address this complex of species in their paper "Primula cusickiana (Primulaceae) and its varieties", Brittonia 53: 154-156. The Flora of North America key relies on merely the length of the corolla tube to distinguish the varieties, but the close relationships were determined by genetic study (unpublished, but see also "Are any primroses (Primula) primitively monomorphic?", Mast, Kelso, Conti, New Phytologist 171, issue 3: 605-616, 2006. It is noted that though Primula capillaris is also very closely related it has been kept as a distinct species. What is also interesting about these species is their specific habitats and very restricted distribution: P. cusickiana in sandy and clay soils among sagebrush in SW Idaho and NE Oregon, P. nevadensis on limestone screes above timberland in Eastern Nevada, P. maguirei on limestone outcrops along the bottom of Logan Canyon and P. domensis along limestone rocks in Western Utah.

Primula cusickiana (var. domensis) in cultivation
 

Pam Eveleigh © 2016