The fern genus Polystichum has presented major problems in definition and circumscription of species since its description by Roth in 1799. Part of the problem is the vast diversity within the genus: the number of species is reported as more than 175 by Copeland (1947). In addition, hybridization is extremely common (Knobloch, 1976), and agamospory has been reported among experimental plants from Europe (Vida & Reichstein, 1975). There is also substantial evidence of phenotypic and ontogenetic variability within species of the genus. Good progress has been made in solving evolutionary and taxonomic problems in the north-temperate and boreal regions (Manton, 1950; Manton & Reichstein, 1961; Kurata, 1964; Sleep & Reichstein, 1967; Daigobo, 1972; W. Wagner, 1973; D. Wagner, 1979); however, little taxonomic and virtually no evolutionary work has been done on the genus in tropical or austral regions. Hence this large genus of dryopteroid ferns is in need of substantial attention from systematic and evolutionary biologists, especially in tropical regions. Christopher Haufler at the University of Kansas organized a symposium on Polystichum for the American Institute of Biological Sciences meetings in Fort Collins, Colorado, during August of 1984. As Haufler noted in his opening remarks, the purpose of the symposium was to draw attention to a complex and poorly understood genus of ferns, rather than to solve problems by consensus of the speakers. Participants in the symposium focused on the evolutionary problems encountered in New World Polystichum, primarily from a taxonomic and floristic viewpoint. This paper summarizes the Fort Collins symposium.