A genus of about 40 species, cosmopolitan.
ID notes:The two species are somewhat cryptic, and the relatively frequent triploid backcross makes field identification still more problematic. Individuals not identified to species may be referred to as “Polypodium virginianum complex”. The hybrid between our 2 species, P. ×incognitum Cusick has features generally intermediate and can be best identified by its spores abortive and malformed (vs. fertile and well-formed).
Ref: Bryan & Doltis (1987); Cusick (2002); Haufler & Windham (1991); Haufler et al. (1993) In Flora of North America Editorial Committee (1993b); Haufler, Windham, & Rabe (1995); Hennipman, Veldhoen, & Kramer In Kramer & Green (1990); Kott & Britton (1982). Show full citations.