References: Smith in FNA (1993b).
A family of about 35-40 genera and 500-700 species, cosmopolitan, especially tropical.
1. Leaf blade densely scaly on the lower surface; leaf segment margins entire; rhizome 1-2 mm in diameter......Pleopeltis
1. Leaf blade scaleless on the lower surface; leaf segment margins denticulate; rhizome 3-6 mm in diameter......Polypodium
Pleopeltis Humboldt & Bonpland ex Willdenow (Shielded-Sorus Polypody)
References: Windham (1993); Andrews & Windham in FNA (1993b).
A genus of about 50 species, primarily tropical.
Pleopeltis polypodioides (Linnaeus) E.G. Andrews & Windham ssp. michauxiana (Weatherby) E.G. Andrews & Windham, Resurrection Fern. Cp, Pd, Mt (NC, SC, VA): on tree limbs and trunks (especially when leaning) and on rocks; common (rare in n. VA). June-October. Ssp. michauxianaranges from se. MD, IL, MO, and se. KS, south to s. FL and TX; also in Mexico and Guatemala. Ssp. polypodioides ranges in the West Indies, Central America and South America. Four additional varieties are tropical in Central America, South America, and Africa. [= FNA, K; Polypodium polypodioides (Linnaeus) Watt -- RAB, infraspecific taxa not distinguished; Polypodium polypodioides (Linnaeus) Watt var. michauxianum Weatherby -- C, F, G, W; Marginaria polypodioides (Linnaeus) Tidestrom -- S]
Windham (1993) makes a compelling case, based on morphological, chemical, and molecular data, that the "scaly polypodies" (including the above taxon) are more closely related to Pleopeltis and should be placed there, rather than in Polypodium.
Polypodium Linnaeus (Polypody) (also see Pleopeltis)
References: Haufler et al. in FNA (1993b); Haufler, Windham, & Rabe (1995), abbreviated as Z; Haufler & Windham (1991); Bryan & Soltis (1987); Kott & Britton (1982.
A genus of about 100 species, cosmopolitan.
1. Leaf blade averaging 5.8 cm wide (range of 3.2-8.2 cm), widest at the base, thus the blade elongate-deltoid in outline; rhizome scales averaging 1.1 mm wide, mostly golden brown throughout; paraphyses (sporangiasters) usually more than 40 per sorus (range of 25-120); leaves mostly lobed to apex, without an attenuate, unlobed tip...... P. appalachianum
1. Leaf blade averaging 4.5 cm wide (range of 3.0-5.8 cm); blade widest near the middle, thus the blade oblong to narrowly lanceolate in outline; rhizome scales averaging 1.5 mm wide, mostly brown, with a dark central stripe; paraphyses (sporangiasters) usually fewer than 40 per sorus (range of 7-69); leaves mostly with an attenuate, unlobed tip...... P. virginianum
Polypodium virginianum Linnaeus [P. virginianum complex], Common Rockcap Fern. Mt, Pd, Cp (NC, SC, VA): moist rocks; common (rare in Coastal Plain). June-October. 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). 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 must be treated as species and given names. Unfortunately, the two species are somewhat cryptic, and the relatively frequent triploid backcross makes field identification still more problematic. Individuals not identified to species may be referred to as "Polypodium virginianum complex." The chromosome complement of P. virginianum can be symbolized as AASS. [= FNA, K, Z; P. virginianum -- RAB, C, F, S, W, in part only (see also P. appalachianum); P. vulgare Linnaeus var. virginianum (Linnaeus) Eaton -- G, in part only (see also P. appalachianum)]
The triploid hybrid [P. appalachianum H virginianum] is rather frequent; there is some evidence that it may reproduce successfully via apogamous spores. It is best recognized by the spores, which are irregular in size and shape. Morphologically, it tends to intermediacy between the two parents, but can closely resemble either. Its chromosome complement can be symbolized AAS.
Flora of the Carolinas and Virginia, Working Draft of 27 October 1997 -- KEY TO PTERIDOPHYTE GENERA. Alan S. Weakley. The Nature Conservancy, Southeast Regional Office, Southern Conservation Science Department.