This occurs on calcareous rocks across southern states and northern Mexico. In Ky. it is known for sure only from cliffs along the Red Rv. in LOGA: M. Medley [& R. Cranfill] #1305-79. Other reports have not been verified (KSNPC) or were based on misidentification (SERNEC). Chromosome number in this species and its close allies, together with other characters, have suggested some affinity with Pellaea, but generic assignments remained uncertain until recently (Cranfill 1980, FNA 2, W). In the U.S.A., plants are apogamous triploids (2n = 87).