Sp. Pl. 2: 1096. 1753
Illustrator: John Myers
Phenology: Sporulating spring–summer.
Habitat: Moist calcareous cliffs, banks, and ledges along streams and rivers, walls of lime sinks, canyon walls (in the American southwest), around foundations, on mortar of storm drains
Elevation: 0–2500 m
B.C., Ala., Ariz., Ark., Calif., Colo., Fla., Ga., Ky., La., Miss., Mo., Nev., N.Mex., N.C., Okla., S.C., S.Dak., Tenn., Tex., Utah, Va., Mexico, West Indies, Central America, South America in Venezuela, Peru, tropical to warm temperate regions in Eurasia and Africa.
No evident pattern to morphologic variation in the species is discernible, although a number of segregate species and infraspecific taxa have been recognized within North American Adiantum capillus-veneris. In the Eastern Hemisphere, the species is diploid, with 2n = 60 (I. Manton 1950). Several tetraploid counts have been reported from North America (W. H. Wagner Jr. 1963). Spore-measurement data suggest, however, that the polyploid cytotype may not be widely distributed. Further investigation is needed to determine whether Adiantum capillus-veneris populations in North America are conspecific with those in Eurasia and Africa.