Monographs Details: Polystichum
Authority: Mickel, John T. & Beitel, Joseph M. 1988. Pteridophyte Flora of Oaxaca, Mexico. Mem. New York Bot. Gard. 46: 1-580.
Description:Genus Description - Terrestrial or epipetric; rhizome ascending to erect, short, compact, usually stout, heavily scaly; fronds medium-sized to large, rarely small, crown-forming; stipe usually densely scaly; blade pinnate to bipinnate, rarely tripinnate, anadromous, often proliferous with rachis bud near apex or in pinna axils; segments thin to more commonly subcoriaceous to coriaceous, usually with spinulose teeth, glabrous to densely scaly below, especially on veins and axes; veins free, forking; sori abaxial, round, typically with peltate indusium, or with indusium lacking; spores bilateral.
Discussion:Lectotype (chosen by Schott, loc. cit.): Polystichum lonchitis (Linnaeus) Roth [=Polypodium lonchitis Linnaeus]. See Pichi Sermolli (Webbia 9: 436. 1953) for more on typification.
Polystichum is a largely temperate genus of nearly 200 species, with most of the tropical species in regions of higher elevations, although a few occur at middle elevations in wet forests. The genus is difficult to circumscribe and distinguish clearly from Cyrtomium, Phanerophlebia, and Plecosorus, and a broad view of Polystichum could include all of these. The genus is distinguished in Oaxaca by its peltate indusium, bipinnate blade and free veins.
The species of Polystichum are difficult to define, due probably to hybridization as evidenced by their promiscuity in northwestern North America, Europe, and Japan. Extensive work needs to be done on the cytology and study of individual populations to better define the species dynamics in tropical America. A. R. Smith (1981) is followed here in large part.