Polypodium virginianum Linnaeus. Common Rockcap Fern, Common Rock Polypody. Phen: Jun-Oct. Hab: Moist rocks. Dist: Haufler and Windham (1991) indicate that the tetraploid cytotype (P. virginianum) of the P. virginianum complex is an allotetraploid derivative of the sterile hybrid of the diploid occurring in our area (P. appalachianum) and another diploid with a boreal distribution (P. sibiricum Siplivinsky)

Origin/Endemic status: Native

Other Comments: Electrophoretic evidence supports this finding (Bryan & Soltis 1987, Haufler, Windham, & Rabe 1995). Thus, Polypodium in our area is another classic example of the reticulate evolution of pteridophytes, and the cytotypes warrant recognition as independent species, though their morphological identification is problematic. The chromosome complement of P. virginianum can be symbolized as AASS.

Synonymy: = Ar, FNA2, Il, K1, K3, K4, Mo1, NE, NY, Pa, Tat, Tn, Va, Haufler, Windham, & Rabe (1995); < Polypodium virginianum L. – C, F, GrPl, RAB, Sf, Tat, W, WV; < Polypodium vulgare L. – S13; < Polypodium vulgare L. var. virginianum (L.) Eaton – G

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Heliophily: 3