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..
1803. Not Jacq. 1786. Asplenium pycnocarpon Spreng. Anleit. 3: 112. 1804. Athyrium pycnocarpon Tidestrom, Elys. Marianum 36.
Rootstock stout, creeping, rooting along its whole length. Stipes clustered, naked, dark brown at the base, green and somewhat fleshy above, 8'-15' long; blades lanceolate to lanceolate-ovate, I°-2 1/2° long, once pinnate, glabrous, membranous; pinnae 20-30 pairs, 2'-5' long, short-stalked, lightly crenulate, linear-oblong, attenuate, flaccid, obtuse or broadly cuneate at the base, those of the fertile blades usually smaller and considerably narrower than those of the fertile, often falcate; sori 20-30 pairs, close, linear, slightly curved, oblique; indusium firm, convex, concealed by the strongly confluent sori at maturity.
Asplenium Ruta-muraria L. Sp. PL 1081. 1753-
Rootstock short, creeping or ascending, the small evergreen leaves closely clustered. Stipes naked, 2-3' long, green throughout; blades ovate or deltoid-ovate, 2-5' long, glabrous, evergreen, 2-3-pinnate, at least below; pinnae and pinnules mostly alternate, stalked; pinnules very variable in shape, size and marginal cutting, commonly rhombic or obovate, obtuse, with the margins dentate or incised, but often cuneate-spatulate, the margins deeply fimbriate; veins flabellate; sori few, linear-oblong, confluent when mature and covering nearly the whole pinnule; membranous, delicate.
On limestone, Vermont to southern Ontario and Michigan, south to Alabama and Missouri. Ascends to 2100 ft. in Virginia. Also in Europe, Asia and northern Africa. July-Sept. Dwarf Spleenwort. Tentwort. Stone-rue. Stone-fern. Rue-fern. White maiden-hair. A hybrid between this species and A. Trichomones, described originally from European specimens, has been found also in Vermont.
Asplenium montanum Willd. Sp. PI. 5: 342. 1810.
Rootstock short, creeping, dark-chaffy at the apex. Stipes tufted, slender, naked, dark brown at the base, green above, 2'-4 1/2' long; blades deltoid-ovate to deltoid-lanceolate, acuminate, rather firm, evergreen, 1-2-pin-nate; lower pinnae largest, deltoid, pinnate or pinnatifid, the lobes or segments ovate or rhombic-oblong, dentate, often narrowly cuneate; upper pinnae less divided, merely toothed or incised; rachis green, winged toward the apex; veins obscure; sori linear-oblong, short, the lower ones sometimes double, usually abundant, often confluent at maturity and concealing the narrow membranous indusia.
On dry and moist rocks, Connecticut and New York to Ohio, south to Georgia, Alabama and Arkansas. Ascends to 4500 ft. in North Carolina. June-Aug.
Rootstock short, ascending, clothed with narrow dark scales at the apex. Stipes tufted, 1'-3' long, somewhat blackish at the base, especially on the inner side, usually glabrous; blades linear-lanceolate, broadest above the middle, 2-3-pinnate, 3'-6' long, 6" - 1 1/2 wide, acuminate, gradually narrowed at the base, the lower pinnae often greatly reduced; rachis narrowly winged; pinnae 10-15 pairs, deltoid-lanceolate to ovate, or the lower ones fan-shaped and flabellately divided, the segments deeply dentate with spinulose teeth; sori short, only 1 to 4 on each segment, rarely confluent; indusia membranous, sub-entire.
Rootstock short, covered with dark narrow scales. Stipes tufted, slender, 2'-3 1/2' long, dark chestnut-brown throughout, shining; blades oblong-lanceolate to oblong, acuminate or scarcely narrowed at the base, pinnate, with 8-12 pairs of short-stalked mostly oblong-ovate. obtuse pinnae, the lower pinnae often unequally deltoid, pinnatifid or pinnate with oblong obtuse lobes or pinnules, these toothed at the apex, the upper pinnatifid with dentate or nearly entire lobes; rachis brown or greenish above; sori short, borne near the midveins; indusia membranous, persistent.
On rocks. preferring limestone, New York to Georgia Alabama, Arkansas and Missouri. Local. July-Sept.