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 and usually rigid erect ferns of harsh texture, with pinnatifid to quadripinnatifid leaves borne typically in a crown upon a suberect or decumbent rootstock, the stipe not jointed to it. Sterile and fertile leaves similar, the vascular parts usually chaffy; divisions of the blade mainly auriculate and spinulose or mucronate, with free veins. Sori round; indusium superior, orbicular, attached at its middle. [Greek, signifying many rows, in allusion to the numerous regular rows of sori in P. Lonchitis (L.) Roth, the typical species.]
About 100 species, of wide distribution, mainly in temperate regions.
Leaves simply pinnate.
Lower pinnae gradually much reduced; upper (soriferous) pinnae conform.
Lower pinnae scarcely reduced; upper (soriferous) pinnae of fertile fronds contracted.
Leaves bipinnatifid or bipinnate.
Leaves coriaceous, the pinnae deeply lobed at their base.
Leaves herbaceous, fully bipinnate.
1801. Polystichum Lonchitis Roth, Rom. Arch. Bot. 21: 106.
1799. Dryopteris Lonchitis Kuntze, Rev. Gen. PI. 813. 1891.
Rootstock short, stout, densely chaffy. Stipes 1' - 5' long, bearing large ferruginous scales with smaller ones intertnixed; blades rigid, coriaceous, evergreen, 6'-2° long, linear-lanceolate, once pinnate; pinnae numerous, close, broadly lanceolate-falcate, l'-l 1/2' long, acute, strongly auricled on the upper side at the base, obliquely truncate below, notably spinulose-dentate, the lowest commonly triangular and shorter; sori large, borne usually in two rows, nearly equidistant between the margin and midrib, subconfluent with age; indusium entire.
On rocks, Labrador to Alaska, south to Nova Scotia, Ontario, Wisconsin, Montana and Washington, and in the mountains to Utah, Colorado and California. Also in. Greenland, Europe and Asia. Called also Rough alpine fern. Aug.
Nephrodium acrostichoides Michx. Fl. Bor. Am. 2: 267.
1803. Aspidium acrostichoides Sw. Syn. Fil. 44. 1806. Polystichum acrostichoides Schott, Gen. Fil. 1834. Dryopteris acrostichoides Kuntze, Rev. Gen. PI. 812. 1891.
Rootstock stout, creeping. Stipes 5-7 long, densely chaffy; blades lanceolate, 1°-2° long, 3'-5' wide, rigid, evergreen, subcoriaceous, once pinnate; pinnae 1'-3' long, narrowly oblong-lanceolate, somewhat falcate, acutish at the apex, half halberd-shaped at the base, with appressed, bristly teeth, the lower pinnae scarcely smaller, sometimes deflexed; fertile fronds contracted at the apex, the reduced pinnae soriferous, their under surface nearly covered with large contiguous sori in 2-4 rows, confluent with age; indusium entire, persistent.
In woods and on hillsides, most abundant in rocky places, Nova Scotia to Ontario and Wisconsin, south to Texas and the Gulf states. Ascends to 2700 ft. in Maryland. July-Aug. Called also Christmas shield-fern.
Forms with cut-lobed or incised pinnae are known as var. Schweinitsii; occasional forms are 2-pinnatifid.