Coefficient of Conservatism:
Coefficient of Wetness:
ex W. H. Wagner slide collection
Rock outcrops, talus boulders, crevices in limestone pavement, in shade or partial shade.
Two subspecies, best distinguished by spore size, occur in Michigan, the tetraploid subsp. quadrivalens D. E. Mey., which prefers calcareous substrates, and the more rare diploid subsp. trichomanes, which prefers acidic substrates.