The diploid Pellaea cordifolia has often been treated as a variety of the Central American and South American apogamous triploid, P . sagittata . The two taxa are distinguished by a number of qualitative morphologic features (A. R. Smith 1980), and it seems unlikely that they represent cytotypes of a single species. A. F. Tryon (1957) suggested that P . sagittata may have originated through hybridization between P . ovata and P . cordifolia (as P . sagittata var. cordata ).