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..
Acrostichum alpinum Bolton, Fil. Brit. 76. 1790.
W. alpina S. F. Gray, Nat. Arr. Brit. PI. 2: 17. 1821.
Rootstocks short, ascending, the leaves densely caespitose. Stipes slender, chestnut-colored, shining, somewhat chaffy below, jointed near the base; blades narrowly oblong-lanceolate, 2'-6' long, 8"-12" wide, scarcely narrower below the middle, deeply bipinna-tifid; pinnae somewhat apart, cordate-ovate or triangular-ovate, pinnately 5-7-lobed, glabrous or very nearly so on both surfaces; sori near the margin, usually distinct; indusium as in the preceding species.
On moist rocks, Labrador to Alaska, Maine, northern New York and western Ontario. Also in Greenland. Ascends to 4200 ft. in Vermont. July-Aug. Called also Northern Woodsia, Flower-cup-fern.
Woodsia glabella R. Br. App. Franklin's Journ. 754. 1823.
Rootstocks small, ascending, densely clustered. Stipes very slender, usually stramineous, jointed above the base; blades delicate, linear or narrowly lanceolate, 2-5' long, 4"-8" wide, once pinnate; pinnae deltoid to roundish-ovate, crenately lobed, glabrous, the lower pinnae remote, obtuse, often somewhat smaller than the middle ones; sori few, distinct or with age confluent; indusium minute, with 6-10 hair-like incurved or radiating segments.
On moist rocks, Labrador to Alaska, south to New Brunswick, northern New England, northern New York and British Columbia. Also in Greenland and arctic and alpine Europe and Asia. Summer.
Rootstock short, creeping, densely chaffy, the numerous leaves borne close together. Stipes 2'-6' long, not jointed, bright rusty or chestnut-colored at the base, paler above; blades lanceolate, 6'-12' long, finely glandular-puberulent and usually his-pidulous with jointed whitish hairs; pinnae numerous, oblong-ovate, deeply pinnatifid into 10-16 oblong toothed segments, or fully pinnate, the larger pinnules nearly free and deeply incised; indusium concealed, cleft into narrow or slender spreading flaccid segments.
In crevices of rocks, Michigan and western Ontario to British Columbia, south in the Rocky Mountains to Arizona and in the Sierra Nevada to California. Also in Gaspe County, Quebec. Summer.
Woodsia oregana D. C. Eaton, Can. Nat. II. 2: 90. 1865.
Rootstock short, creeping, chaffy, the numerous leaves very densely clustered. Stipes not jointed, brownish and chaffy below, paler or stramineous above, glabrous; blades 2'-10' long, elliptic-lanceolate, deeply bipinnatifid or partially bipinnate, the sterile shorter than the fertile; pinnae glabrous, deltoid-oblong, obtuse, deeply pinnatifid, the lower smaller and remote; segments oblong or ovate, obtuse, ad-nate or the largest nearly free, dentate or crenate, the teeth often revolute and covering the submarginal sori; indusia minute, concealed, consisting of a few short whitish turgid hair-like segments.
British Columbia and Athabasca to Manitoba, Wisconsin, northern Michigan, Nebraska, Oklahoma, Colorado, Arizona and California. Also in eastern Quebec. July-Aug.
Polypodium obtusum Spreng. Anleit. 3: 92. 1904. Woodsia obtusa Torr. Cat. PI. in Geol. Rep. N. Y. 195. 1840.
Rootstock short, creeping, with relatively few leaves. Stipes not jointed, straw-colored, chaffy, 3'-6' long; blades broadly lanceolate, 6'-15' long, minutely glandular-puberulent, nearly or quite 2-pin-nate; pinnae rather remote, triangular-ovate or oblong, pinnately parted into oblong obtuse crenate-dentate segments, or usually pinnate, the lower pinnules free and parted nearly to the midveins; sori nearer the margin than the midveins; indusia conspicuous, at first enclosing the sporanges, at length splitting into several broad jagged spreading lobes.
On rocks, Nova Scotia and Maine to Wisconsin and south to Georgia, Alabama, and Texas. Also in Alaska and British Columbia. Variable. Ascends to 2200 ft. in Virginia.