Pleopeltis polypodioides is a widespread Neotropical epiphytic fern species currently composed of six varieties: acicularis (Weath.) E.G. Andrews & Windham, burchellii (Baker) A.R. Sm., knoblochianum Mickel, michauxiana (Weath.) E.G. Andrews & Windham, minus (Fée) Weath., and polypodioides (L.) E.G. Andrews & Windham, plus one subspecies: ecklonii (Kunze) Roux. The species was initially included within Polypodium but recent authors, utilizing molecular data, have placed it within Pleopeltis. The taxonomic boundaries of Pleopeltis remain controversial despite recent investigations into its circumscription. The objectives of this dissertation were to explore the taxonomic affinity of the Pl. polypodioides complex within Pleopeltis, and its interspecific relationships using molecular phylogenies and morphological analyses. In addition, generic affinities and geographic distributions of Pl. polypodioides, as well as infraspecific relationships were examined. Originally, differentiation among the members of the complex was based primarily on leaf venation pattern and the presence or absence of laminar (leaf) scales on the adaxial (upper) surface. This species is characterized by an epiphytic habit, deeply pinnatifid fronds, round sori that are embedded into the laminar tissue creating an embossed appearance on the upper service of the leaf, a covering of persistent scales on the lower (abaxial) surface, free and/or anastomosing leaf venation, and sori supplied by a single vein. Glandular structures are present on the acroscopic side of the pinnae-segments, and rhizome scales have a black center at the point of attachment and generally with a black sclerotic medial band. In addition to an epiphytic habit, this species exhibits a particularly fascinating aspect of desiccation tolerance. When conditions become dry, the fronds completely curl inward and remain dormant until water is more readily available. Once moisture increases, the fronds rapidly unfurl by channeling water directly into the frond surface through scale attachments. The re-hydration can occur within hours, and the fronds revive and "resurrect", hence the common name: resurrection fern. The geographic distribution of the species ranges from the southeastern United States with a southwest extension into Mexico, central Mexico, Central America and the West Indies. It occurs through southern Mexico and into South America along the eastern coast, southern Brazil, Paraguay, Uruguay and northern Argentina, and the southeastern coast of Africa. Despite the extensive range of the species complex, individual varieties have relatively limited distributions with only slight overlap. Phylogenetic analysis of combined chloroplast DNA sequences of the trnLUAA-trnFGAA region (including the trnL intron and intergenic spacer trnL-trnF), and the trnHGUG-psbA intergenic spacer revealed that Pl. polypodioides is not monophyletic, however support for each of the original seven taxa within the complex was strong and revealed the presence of an additional species in southern Mexico. Morphological analyses also support the recognition of eight species. Diagnostic features and geographic ranges of all of the recognized taxa have been documented, and I propose to the raise varieties acicularis, burchellii, knoblochianum, michauxiana, minus, polypodioides, and subspecies ecklonii to species status in addition to describing the new species, Pleopeltis constricta.