Hay-scented fern, dennstaedtie à lobules ponctués

Nephrodium punctilobulum Michaux, Fl. Bor.-Amer. 2: 268. 1803

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.

Sporulates in summer. Rocky slopes, meadows, woods, stream banks, and roadsides, in acid soils; 0--1200 m; N.B., Nfld., N.S., Ont., P.E.I., Que.; Ala., Ark., Conn., Del., Ga., Ill., Ind., Ky., Maine, Md., Mass., Mich., Mo., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Tenn., Vt., Va., W.Va., Wis.

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.