Stems long-creeping, 2--3 mm diam. Leaves clustered, erect, 0.4--1(--1.3) × 0.1--0.3 m. Petiole straw-colored to brown, darker at base, dull, ca. 1/2 length of blade, pubescent with soft, jointed hairs. Blade yellow-green or pale green, dull, lanceolate, 2-pinnate-pinnatifid, ca. 3 times as long as wide, base slightly narrowed but truncate, apex acuminate, with soft, silver-gray, jointed hairs on both surfaces. Basal segments of pinnules opposite; ultimate segments ovate to lanceolate, base equilateral, truncate, margins deeply lobed, serrate-crenate. Sori globose to almost cylindric; indusia tubular to cylindric. Spores trilete, globose with low, tuberculate, distal face and equatorial flange. 2 n = 68.
Reports of occurrences of Dennstaedtia punctilobula in Iowa are based on incorrectly labeled specimens collected in Massachusetts (T. S. Cooperrider 1968). Dennstaedtia punctilobula spreads aggressively in open woods and clearings.
Lvs mostly 4-8 dm, the petiole elongate, to 2 dm, basally castaneous, the fragrant blade lanceolate or lance-ovate, to 25 cm wide, bipinnate-pinnatifid; pinnae 17-25 pairs, alternate or subopposite, short-petiolulate, lanceolate, to 13 נ4.5 cm, the pinnules subsessile, 14-25 pairs, deeply pinnatisect, the segments typically 6-8 pairs, ovate, with 2-3 oblique acute teeth on each side; rachises, costae, and costules with short, spreading, glandular hairs; 2n=68. Mostly in open woods or clearings or on rocky slopes; Nf. and N.S. to Ont. and Minn., s. to Ga., Ala., and Ark. (Dicksonia p.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
This fern seems to be rare in the state. It prefers the sandstone and shaly rocks of deep, wooded ravines. Williamson, in "Ferns of Kentucky," says it was found along Silver Creek north of Louisville, Kentucky. It was rather common in a rocky ravine in Turkey Run State Park. Outside of Indiana in suitable habitats it often becomes an annoying weed in pastures.