Asplenium platyneuron (Linnaeus) Britton, Sterns, & Poggenburg. Phen: (Jan-) Apr-Oct (-Dec). Hab: Moist to dry soils of forests, woodlands, old fields; also on outcrops, especially of calcareous rocks and in masonry crevices, at low to moderate elevations. Dist: QC, ON, se. MN, IA, and se. CO south to FL, TX, NM, and AZ (and varieties or relatives reported from Central and South America); Slovakia; South Africa.
Origin/Endemic status: Native
Taxonomy Comments: A. platyneuron var. incisum does not seem to warrant taxonomic recognition. Strikingly large plants of the outer Atlantic Coastal Plain and Gulf Coastal Plain have been named var. bacculum-rubrum (Featherman) Fernald; they are probably not worthy of taxonomic recognition. They can be distinguished as follows: var. bacculum-rubrum has the longest pinnae > 3.5-6 cm long, the pinnae often coarsely serrate-incised to pinnatifid and the larger leaves to (30-) 40-70 (-100) cm tall, with 45-70 pairs of pinnae (vs. longest pinnae < 3.5 cm long, pinnae subentire to pinnatifid, larger leaves to 20-45 (-50) cm tall, with 25-50 pairs of pinnae).
Other Comments: This species is one of the diploid progenitors involved in the reticulately evolved Appalachian Asplenium complex. It is one parent of A. bradleyi and A. ×ebenoides (as well as other sterile hybrids). A. platyneuron in general, and var. platyneuron specifically, is by far the most common of our Asplenium species, and the only one found characteristically away from rock.
Synonymy: = Ar, C, ETx1, Fl1, FNA2, GrPl, K3, K4, Mo1, NE, NY, Ok, Pa, RAB, S13, Sf, Tat, Tn, Tx, TxFerns, Va, W, WH3, WV, Keener & Davenport (2007); > Asplenium platyneuron (L.) Britton, Sterns, & Poggenb. var. bacculum-rubrum (Featherm.) Fernald – F, G, K1, Taylor, Mohlenbrock, & Burton (1976); > Asplenium platyneuron (L.) Britton, Sterns, & Poggenb. var. incisum (Howe ex Peck) B.L.Rob. – F, Il, Taylor, Mohlenbrock, & Burton (1976); > Asplenium platyneuron (L.) Britton, Sterns, & Poggenb. var. platyneuron – F, G, Il, K1, Taylor, Mohlenbrock, & Burton (1976)