Plants perennial, terrestrial, on rock, or often epiphytic, erect, arching, or occasionally pendent. Stems long- to short-creeping, branched or not, bearing scales and few to numerous roots, usually dictyostelic. Leaves monomorphic to dimorphic, circinate in bud. Petiole usually articulate at base [rarely nonarticulate, as in Loxogramme ], lacking scales or sometimes scaly, with usually 3 vascular bundles. Blade
petiole, rachis, costae, and sometimes blade tissue usually bearing hairs (these often septate and with reddish crosswalls) and/or scales. Sori
borne abaxially on veins, round to oblong, occasionally elongate, rarely marginal, rarely covering surface; paraphyses present or absent; sporangia with stalk of 2 or 3 rows of cells; indusia absent. Spores
usually transparent or yellowish (rarely greenish), all 1 kind, bilateral, monolete [rarely trilete, as in some Loxogramme
], surface most often smooth, tuberculate, verrucose, or granulate, occasionally spiny, 64 per sporangium (spores globose and 32 per sporangium in apogamous spp.). Gametophytes
green, aboveground, cordate or elliptic, glabrous or sometimes glandular; archegonia and antheridia borne on lower surface, antheridia 3-celled.
Genera ca. 40, species perhaps 500 (7 genera, 25 species in the flora): worldwide, especially tropics and subtropics.
Phymatosorus scolopendria (Burman f.) Pichi-Sermolli, native to the Old World, is a rare escape in southern Florida. Genera in this family are variously circumscribed, and the New World species historically were placed in the single genus Polypodium . Many of the segregates recognized here are still placed in Polypodium in recent floristic accounts. Limits of genera in both Old World and New World are controversial and are currently under study by several workers.
(Key to genera of Polypodiaceae)