Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Lvs glabrous, evergreen, shiny, often dimorphic; petiole slender and wiry, mostly brown; blade 2–4 times pinnate, the ultimate segments ± elongate, distantly toothed, with free veins; margins of the fertile segments reflexed and abruptly white-scarious (in ours), forming a well defined common false indusium for the submarginal sori; small, mesophytic rock-ferns with a short rhizome beset with firm, narrow, dark brown scales. 3 Amer., 1 Afr.