Monographs Details: Polystichum
Authority: Proctor, George R. 1989. Ferns of Puerto Rico and the Virgin Islands. Mem. New York Bot. Gard. 53: 1-389.
Family:Dryopteridaceae
Scientific Name:Polystichum
Description:Species Description - Terrestrial fems of small to moderate size. Rhizomes woody, erect or decumbent, sometimes stout (including persistent stipe bases), densely scaly at the apex. Fronds erect, arching, or recurved, stipitate; stipes usually scaly, not articulate. Blades mostly 1- to 3-pinnate, or rarely nearly simple, anadromic, uniform or rarely somewhat dimorphic, often proliferous by scaly buds on rhachis or at apex, the vascular parts more or less scaly or fibrillose but true hairs lacking; tissue usually of coriaceous texture. Ultimate divisions mainly inequilateral, more or less auriculate, usually serrate to spinulose; veins always free, the tips often not quite reaching the margins. Sori round, dorsal to subterminal on veins; indusium orbicular and centrally peltate, persistent or deciduous, or sometimes lacking; sporangia with annulus of 18 or more cells; spores ellipsoid to nearly spheroid, monolete, with irregular, saccate or winglike folds, the surface more or less (often very minutely) spinulose.

Discussion:

Type Species. Polystichum lonchitis (Linnaeus) Roth, based on Polypodium lonchitis Linnaeus, of north temperate regions.

A large genus of perhaps 175 species, cosmopolitan in over-all distribution, but the majority of the species occur in north and south temperate regions and on tropical mountains. Five species are now known to occur in Puerto Rico, two of these only recently discovered here; none are endemic. The generic name is derived from the Greek poly, many + stichos, row, because the sori of the type species are in many regular rows on the pinnae.

Special Literature. Maxon, W . R. 1909. A revision of the West Indian species of Polystichum. Contr. U.S. Natl. Herb. 13: 25-29, t. 2-9; Maxon, W . R. 1912. Further notes on the West Indian species of Polystichum. Op. cit. 16: 49-51, t. 27; Tryon, R. M . & A. F. Tryon. 1982. Fems and allied plants, pp. 524-533, 29 figs.