Cystopteris protrusa (Weatherby) Blasdell. Phen: Apr-Jun. Hab: Rich woods or on moss- and soil-covered talus in boulderfields, loess bluffs, occasionally on ledges of rock outcrops. Dist: NY and ON west to MN, south to GA, Panhandle FL (Washington and Gadsden counties) (Wunderlin & Hansen 2006; L. Byrd, pers.comm., 2020), AL, MS, LA, e. TX, and OK.
Origin/Endemic status: Native
Taxonomy Comments: This species is a diploid involved in the reticulate evolution of Cystopteris in e. North America. It is one parent of C. tennesseensis and C. tenuis. Its genome can be symbolized PP.
Synonymy: = Ar, C, ETx1, Fl1, FNA2, GrPl, Il, K1, K3, K4, Mo1, NE, NY, Pa, RAB, Tn, TxFerns, Va, W, WH3, WV, Shmakov, Batkin, & Vaganov (2018); = Cystopteris fragilis (L.) Bernh. var. protrusa Weath. – F, G, Sf, Tat; < Cystopteris fragilis (L.) Bernh. – Tx; < Filix fragilis (L.) Underw. – S13