English: Narrow-leaved glade fern; Narrow-leaved-spleenwort; Glade fern.
Synonym: Athyrium pycnocarpon; Diplazium pycnocarpon.
Name: pycnocarpos means crowded fruits
Genus: 1 species.
Region: eastern North America.
Habitat: moist woodlands.

BotanyFern; grows from creeping stems.
Leaves: clustered; ± 90 cm, ± 15 cm wide; blade is oblong-lanceolate and once-pinnate; pinnae are linear and either more-or-less entire or with shallow indentations; fertile leaves are similar to the sterile leaves, but narrower, with more widely spaced pinnae.
Sori: long; straight or slightly curved; borne in two lines along the underside of a leaf pinna; indusia are thick and prominent; crowded.

TaxonomyHomalosorus was once classified in the family Athyriaceae due to its linear, often doubled sori. In the Pteridophyte Phylogeny Group classification of 2016 it is placed in the small family Diplaziopsidaceae
Others place the genus in the subfamily Diplaziopsidoideae of a very broadly defined family Aspleniaceae, equivalent to the suborder Aspleniineae in PPG I.