In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), the genus is a very small one with about two species.

At one time,[specify] all thelypterioid ferns were included in the genus Dryopteris because of the sorus shape.

Some researchers include the entire family Thelypteridaceae in the genus Thelypteris.

[citation needed] An intermediate position is to place the bulk in Thelypteris (corresponding to Thelypterioideae of PPG I), which can then be divided into subgenera and sections corresponding to the genera of other authors, but to separate out Phegopteris and Macrothelypteris.

[1] Using the circumscription of the genus in PPG I,[1] as of May 2023[update], the Checklist of Ferns and Lycophytes of the World accepted three species:[2] Other sources place the entire subfamily Thelypteridoideae in the genus, and so accept many more species, including the following (synonyms from the Checklist of Ferns and Lycophytes of the World):[2]