Proctor, George R. 1989. Ferns of Puerto Rico and the Virgin Islands. Mem. New York Bot. Gard. 53: 1-389.
Aspleniaceae
Species Description - Small to medium-sized, tenestrial, epipetric, or epiphytic fems. Rhizomes creeping to erect, dictyostelic, bearing clathrate scales, these often iridescent. Fronds clustered (rarely spaced), not articulate to the rhizome, monomorphic or rarely more or less dimorphic; stipes containing two U-shaped vascular bundles toward base, these back-to-back, fusing toward top of stipe to form a single X-shaped bundle. Blades simple or 1- to 4-pinnate, or variously pinnatifid or decompound, anadromous, usually glabrous or nearly so or rarely pubescent; pinnae often inequilateral, sometimes acroscopically auriculate; veins usually forked, free, rarely a few joined; lower margins of pinnae or pinnules usually decunent. Sori oval to narrowly linear, b o m e along the ultimate veins, occasionally doubled (as in Diplazium); indusium more or less elongate, membranous, laterally attached to vein, opening acroscopically; sporangia with annulus of 20 cells or more; spores more or less ellipsoid to nearly spheroid, monolete, often with prominent, winglike folds, the surfaces smooth to variously echinate or reticulate and often perforate.
Type Species. Asplenium marinum L., of European coastal rocks.
A large, cosmopolitan genus of more than 700 species; 24 are here recorded for Puerto Rico, several of these represented by two or more varieties. Unlike most other large genera, Asplenium is not readily split into discontinuous subgeneric groups, although many ofthe species clearly form related series. This genus requires major monographic analysis for better understanding. The generic name is derived from the Greek a-, with + splenion, spleen, applied by Dioscorides to a fem thought to be useful in treating diseases ofthe spleen.
Special Literature. Maxon, W . R. 1908. Asplenium salicifolium and confused species. Contr. U.S. Natl. Herb. 10: 475^81, t. 15; Maxon, W . R. 1913. Asplenium trichomanes and its American allies, op. cit. 17: 133-153, figs. 1-7, t. 1; Morton, C. V. & D. B. Lellinger. 1966. The Polypodiaceae subfamily Asplenioideae in Venezuela. Mem. New York Bot. Gard. 15: 1-49; Tryon, R. M . & A. F. Tryon. 1982. Ferns and allied plants, pp. 629-645, 48 figs.