Mostly tropical and subtropical, North America, ca. 250 in Mexico, West Indies, Central America, South America.
Circumscription of genera is unsettled and in some cases arbitrarily based on blade dissection. Generic limits need redefinition and are the subject of current study. The family description above encompasses the worldwide variation. Relationships of the family have generally been thought to be with the Polypodiaceae with which the family is sometimes combined, but that is open to question. Most species are epiphytic, and many occur in cloud forests at middle and high elevations.
Genera ca. 10 or more, species ca. 500 or more (1 genus, 1 species in the flora).