This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Rock-loving small or medium-sized ferns, with nearly uniform leaves, the blades 1-3-pinnate, smooth, the fertile divisions commonly narrower than the sterile. Sori roundish or elongate, on the free veins, usually confluent in a submarginal line. Indusium formed by the reflexed margins of the segments. [Greek, alluding to the dark-colored stipes.]
Blades pinnate or 2-pinnate with large pinnules.
Blades small. 3-pinnate, the pinnules narrow.
Pteris atropurpurea L. Sp. PI. 1076. 1753-
Pellaea atropurpurea Link, Fil. Hort. Berol. 59.
P. glabella Mett.; Kuhn, Linnaea 36: 87. 1869.
Rootstock short, densely clothed with long-attenuate rusty scales. Stipes tufted, 2'-8' long, dark purple, smooth, or, with the rachis, more or less pubescent with hair-like chaff; blades coriaceous, lanceolate, ovate-lanceolate or deltoid-ovate, 4'-12' long, 2'-6' wide, simply pinnate, or below 2-pinnate; pinnules and upper pinnae 1'-2' long, glabrous, or sparsely fibrillose below, 3" or less wide, short-stalked or sessile; veins obscure.
On rocks, preferring limestone, Ontario to British Columbia and Mackenzie, Georgia, Mississippi, Texas and California. Reported from northern Mexico. June-Sept. Clayton's Cliff-brake, Rock- or Winter-brake, Indian's Dream.
Onychium densum Brack. Fil. U. S. Expl. Exp.
120. 1854. Pellaea densa Hook. Sp. Fil. 2: 150. 1858.
Rootstocks slender, creeping, entangled, chaffy with narrow blackish scales. Stipes numerous, densely tufted, wiry, slender, light brown, 3'-9' long; blades ovate or triangular-oblong, 1'-3' long, densely 3-pinnate, the segments 3"-6" long, linear, nearly sessile, acuminate or mucronate, those of the fertile blades tapering at each end, with narrowly recurved margins; indusium distinctly scarious; segments of the rarely sterile blades broader and serrate.
Mt. Albert, Gaspe, Quebec and Grey county, Ontario; British Columbia to Montana, Wyoming and California. Summer. Indian's Dream.