Coefficient of Conservatism:
Coefficient of Wetness:
A. A. Reznicek
Rocky ledges, crevices in limestone pavement, low cliffs, and talus slopes. Usually not on exposed vertical cliffs; that habitat more typical of P. glabella.
Long known from the western Upper Peninsula, especially on the Keweenaw Peninsula; first reported from the eastern Upper Peninsula (Drummond Island) by Weatherbee (1990), this eastern population being perhaps more or less contiguous with populations on Manitoulin Island and the northern Bruce Peninsula of Ontario.