Mickel, John T. & Smith, Alan R. 2004. The pteridophytes of Mexico. Mem. New York Bot. Gard. 88: 1-1054.
Polypodiaceae
Genus Description - Epiphytic or epipetric, infrequently terrestrial; rhizomes short- to long-creeping, freely branched, often glaucous, root proliferations absent; rhizome scales concolorous to bicolorous, clathrate or not, peltately attached, surfaces glabrous or hairy, margins entire or toothed; blades pinnatifid to pinnate, infrequently more divided, monomorphic to subdimorphic, stipitate, articulate on phyllopodia; stipes stramineous, rarely dark, channelled (never terete); blades glabrous, hairy, or scaly; veins free or netted, if netted, areoles regular and each with a single, free, included vein; sori round to oblong, exindusiate, paraphyses (abortive sporangia, or branched or filamentous hairs) present or absent, each sorus terminal on lowest acroscopic vein or free included vein if areolate, in one to several rows between costae and margins; sporangia with paraphyses or glabrous; spores bilateral, verrucate, tuberculate, rugose or papillate; x =37.
Lectotype (chosen by J. Sm., Hist. Fil. 88. 1875): Polypodium vulgare L.
Marginaria Bory, Dict. Class. Hist. Nat. 6: 587. 1824. Type: Marginaria ceteraccina (Michx.) Bory [= Polypodium ceteraccinum Michx.] = Polypodium polypodioides (L.) Watt. Goniophlebium sect. Lepicystis J. Sm., J. Bot. (Hooker) 4: 56. 1841. Lepicystis (J. Sm.) J. Sm., London J. Bot. 1: 195. 1842. Type: Lepicystis incana (J. Sm.) J. Sm. [= Goniophlebium incanum J. Sm.] = Polypodium polypodioides (L.) Watt]. Pseudocolysis L. D. Go´mez, Brenesia 10/11: 116. 1977. Type: Pseudocolysis bradeorum (Rosenst.) L. D. Go´mez [= Polypodium bradeorum Rosenst.]. Microphlebodium L. D. Go´mez, Phytologia 59: 58. 1985. Type: Microphlebodium muenchii (Christ) L. D. Go´mez [= Polypodium muenchii Christ].
Polypodium, as defined in the narrow sense, comprises about 100–125 species, mostly of the New World tropics with a few species in the temperate regions of America, Europe, Asia and Africa. The species have pinnatifid to pinnate (rarely simple) fronds, peltate rhizome scales, free or netted venation with single free included veins in areoles, sori terminal on ends of veins or on free included veins, channelled stipes, filamentous or branched paraphyses, and branched rhizomes. The limits of the various generic segregates of Polypodium here recognized (q.v.) and keyed below (Campyloneurum, Microgramma, Niphidium, Pecluma, Phlebodium, and Pleopeltis) are problematic. Within Polypodium itself, there are many problematic species complexes, including those of P. subpetiolatum, P. plesiosorum, P. furfuraceum, P. falcaria, P. plebeium, P. polypodioides, and P. thyssanolepis. The group of free-veined, hairy polypodiums is badly in need of revision. The scaly-bladed species are sometimes included in Pleopeltis, as in the recent Flora of North America treatment (Andrews & Windham in FNA Ed. Comm., 1993), but circumscription of Pleopeltis, thus redefined, and the nonscaly species of Polypodium, should await further study. Recent molecular evidence suggests that generic circumscriptions are in need of serious revision (Schneider et al., 2004).