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..
Coarse lowland ferns with dissimilar leaves in a close crown upon a stout ascending rootstock. Sterile leaves tall, in a complete circle, the shorter fertile leaves appearing late in the season, borne within, rigidly erect, the pinnae closely contracted into necklace-like or pod-like divisions, these concealing the sori, finally dehiscent. Sori roundish, on elevated cylindrical receptacles, partly covered by delicate fugacious lacerate indusia attached below. [Named in honor of Carlo Matteucci, an Italian professor of physics.]
Species 3, the following, which is the generic type, and 2 Asiatic species.
Osmunda Struthiopteris L. Sp. PI. 1066. 1753. Onoclea Struthiopteris Hoffm. Deutsch. Fl. 2: 11.
Palermo 1: 235. 1866.
Rootstock stout, ascending, with slender underground stolons. Fertile leaves 1°-1 1/2° high, the pinnae dark brown, slightly crenate, contracted, with closely and widely revolute margins, the included sori crowded and confluent. Sterile leaves 2°-7° high, 6'-15' broad, broadly oblan-ceolate or spatulate, abruptly short-acuminate, gradually narrowed below the middle, the lower pinnae greatly reduced; pinnae narrow, deeply pinnatifid, glabrous, the segments oblong, obtuse, entire.