Narrow-leaved glade fern, narrow-leaved-spleenwort, glade fern, diplazie à sores denses

Asplenium pycnocarpon Sprengel, Anleit. Kenntn. Gew. 3: 112. 1804; Athyrium pycnocarpon (Sprengel) Tidestrom; Homalosorus pycnocarpos (Sprengel) Pichi-Sermolli

Stems creeping; scales brown, broadly lanceolate, margins entire. Petiole 15--40(--50) cm. Blade oblong-lanceolate, 1-pinnate, 30--75 × 8--25 cm, ± narrowed to base with reduced proximal pinnae, broadest above base, abruptly acuminate to apex. Pinnae linear, ± entire to shallowly crenulate, base truncate or acroscopically auriculate, apex acuminate. Veins usually 1--2-forked, nearly reaching sinuses between crenations. Sori elongate, straight or slightly falcate, single or rarely double; indusia vaulted, ± thick. 2 n = 80.

Moist woods and slopes in neutral soil; 150--1000 m; Ont., Que.; Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Mass., Mich., Minn., Miss., Mo., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Tenn., Vt., Va., W.Va., Wis.

Diplazium pycnocarpon has commonly been placed in Athyrium , but it is closely related to the east Malesian Diplazium flavoviride Alston (M. Kato and D. Darnaedi 1988).