Cystopteris Bernhardi. Bladder Fern, Brittle Fern.
A genus of about 30-35 species, sub-cosmopolitan in distribution, primarily of temperate regions but also in montane to alpine settings in tropical regions.
ID notes: See Woodsia for suggestions on distinguishing between Cystopteris and Woodsia, somewhat similar ferns often confused. Hybrids frequently occur where two or more species of Cystopteris grow in proximity. The following hybrids may be anticipated in our area: Cystopteris bulbifera × tennesseensis, Cystopteris bulbifera × tenuis [= C. ×illinoensis R.C. Moran], Cystopteris fragilis × tenuis, Cystopteris protrusa × tennesseensis, Cystopteris protrusa × tenuis, Cystopteris tennesseensis × tenuis [= C. ×wagneri R.C. Moran].
Ref: Ekrt et al. (2022); Haufler, Moran, & Windham (1993) In Flora of North America Editorial Committee (1993b); Haufler, Windham, & Ranker (1990); Kramer & Green (1990); Rothfels et al. (2014); Shmakov, Batkin, & Vaganov (2018); Wang & Haufler in FoC (2013). Show full citations.