Pteridaceae are one of the largest fern families, comprising over 1000 species (~10% of extant ferns). But even more notable than their species richness is the remarkable morphological and ecological diversity of the family, which includes obligate epiphytes, free-floating aquatics, brackish-swamp dwellers, several clades specialized for colonizing rocky deserts, and many generalist understory species. While some of these life forms do appear in other fern lineages (many other families, for example, contain epiphytes), most are rare and no other fern family contains such a wide range of ecological specializations.

Pteridaceae have been the subject of much taxonomic disagreement—their members have been distributed among at least 20 different families: Acrostichaceae; Actiniopteridaceae; Adiantaceae; Anopteraceae; Antrophyaceae; Bommeriaceae; Ceratopteridaceae; Cheilanthaceae; Coniogrammaceae; Crytopgrammaceae; Hemionitidaceae; Llaveaceae; Negripteridaceae; Notholaenaceae; Parkeriaceae; Platyzomataceae; Pteridaceae; Sinopteridaceae; Taenitidaceae; and Vittariaceae (Smith et al. 1996; Hassler and Swale, 2003). Some of these former family designations (e.g., Llaveaceae, Parkeriaceae, and Vittariaceae) correspond to monophyletic groups now known to be nested within the broader Pteridaceae, while others (e.g., Taenitidaceae) are assemblages of more distantly related species (Schuettpelz et al., 2007).