Proctor, George R. 1989. Ferns of Puerto Rico and the Virgin Islands. Mem. New York Bot. Gard. 53: 1-389.
Polypodiaceae
Description - Small to large epiphytic or epipetric fems of varied habit. Rhizomes short- to long-creeping, often slender, more or less clothed with scales (these often clathrate) or sometimes nearly naked. Fronds articulate to the rhizome, monomorphic or somewhat dimorphic, mostly stipitate, glabrous or hairy, and with or without scales. Blades simple to pinnatisect (or to 3-pinnate in species not found in Puerto Rico), sometimes pectinate; margins usually entire; veins branched, free or variously reticulate, the areoles with or without included free veinlets. Sori round or oval (rarely somewhat linear), mostly terminal on free veinlets, not marginal, usually in one or more regular rows; indusium lacking; paraphyses present or absent; sporangia with annulus of 12-18 cells; spores ellipsoid, monolete, the surface usually more or less verrucose to rugose or tuberculate, or in a few cases smooth with a minute granular deposit.
1754. Type Species. Polypodium vulgare Linnaeus, of northem Europe.
A large cosmopolitan taxon of about 225 species, of which 26 are known to occur in Puerto Rico. These are arranged in a series of subgenera that in altemative systems of classification are often treated as genera. The generic name is derived from the Greek poly, many + podion, foot, because the highly branching rhizome of some species fancifully resembles many feet.
Special Literature. Maxon, W. R. 1916. Polypodium squamatum and its allies. Contr. U.S. Natl. Herb. 17: 579-596, t. 41; Weatherby, C. A. 1939. The group of Polypodium polypodioides. Contr. Gray Herb. 124: 22- 35; Evans, A. M . 1969. Interspecific relationships in the Polypodium pectinatum-plumula complex. Ann. Missouri Bot. Gard. 55: 193-293, 20 figs.; Lellinger, D. B. 1972. A revision ofthe fem genus Niphidium. Amer. Fem J. 62: 101-120; Tryon, R. M . & A. F. Tryon. 1982. Fems and allied plants, pp. 688-702, 42 figs., 702-708, 13 figs., 715-722, 27 figs., 722-727, 20 figs., 727-732, 10 figs; Price, M . G. 1983. Pecluma, a new tropical American fem genus. Amer. Fem J. 73: 109-116, 2 figs.