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..
Mostly medium-sized ferns, with slender wide-creeping hairy rootstocks and scattered 2-3-pinnate erect leaves, 2°-6° high. Sori marginal, terminal upon the free veinlets, the sporanges clustered upon a very small receptacle within a special cup-shaped indusium formed in part of the more or less modified reflexed segment of the leaf-margin. [Name in honor of August Wilhelm Dennstaedt.]
Nephrodium punctilobulum Michx. Fl. Bor. Am. 2: 268.
Rootstock slender, extensively creeping, not chaffy. Stipes stout, chaffless, usually castaneous at the base; blades 1°-3° long, 5'-9' wide, ovate-lanceolate to deltoid-lanceolate, acute or acuminate, frequently long-attenuate, usually 3-pinnatifid, thin and delicate, the rachis and under surface minutely glandular and pubescent; pinnae numerous, lanceolate, the segments ovate to oblong, close and deeply lobed, the margins with oblique rounded teeth; sori minute, each on a recurved tooth, usually one at the upper margin of each lobe; sporanges few, borne within the delicate cup-shaped indusium.
In various situations, most abundant on open hillsides, Nova Scotia and New Brunswick to Ontario and Minnesota, south to Georgia, Alabama and Missouri. Ascends to 5600 ft. in Virginia. Aug. Called also Fine-haired-fern, Hairy dicksonia, Boulder-fern.