Stems short-creeping or ascending. Petiole straw-colored distally, 7–60 cm, base dark redbrown or black, swollen, with 2 rows of teeth; scales light to dark-brown, linear to ovatelanceolate, 7–20 × 1–5 mm. Blade elliptic, lanceolate to oblanceolate, 2-pinnate to 2-pinnate-pinnatifid, 18–30 × 5–50 cm, herbaceous but with cartilaginous margin, narrowed to base, apex acuminate. Pinnae sessile to short-stalked, linear-oblong to lanceolate, apex acuminate. Pinnules pinnatifid, segments oblong-linear to narrowly deltate, margins serrate. Rachis, costae, and costules glabrous or with glands or hairs. Veins pinnate. Sori straight, hooked at distal end, or horseshoe-shaped; indusia dentate or ciliate.

Distribution

North America, Mexico, Central America, South America, Europe, Asia.

Discussion

Athyrium filix-femina is circumboreal, and this or closely related species extend into Mexico, Central America, and South America. The delimitation and infraspecific classification of A. filix-femina need detailed study.

Varieties ca. 5 (4 in the flora).

Selected References

None.

Lower Taxa

Athyrium filix-femina var. angustum, Athyrium filix-femina var. asplenioides, Athyrium filix-femina var. californicum, Athyrium filix-femina var. cyclosorum

Key

1	Petiole scales more than 1 cm; blades ca. 2 times length of petioles, elliptic to oblanceolate.	> 2
1	Petiole scales 1 cm or less; blades 1-1.5 times length of petioles, elliptic to lanceolate.	> 3
2	Pinnules narrowly deltate or oblong-lanceolate, nearly equilateral at base; indusia long-ciliate; spores yellow.	Athyrium filix-femina var. cyclosorum
2	Pinnules linear-oblong or linear-lanceolate, inequilateral at base; indusia dentate or long-ciliate; spores brown.	Athyrium filix-femina var. californicum
3	Petiole scales brown to dark brown; blades elliptic, narrowed to base, broadest near or just below middle; pinnae sessile or short-stalked; pinnules linear to oblong; indusia not glandular; spores yellow.	Athyrium filix-femina var. angustum
3	Petiole scales light brown to brown; blades ovate-lanceolate to lanceolate, slightly narrowed to base, broadest just above base; pinnae usually stalked; pinnules oblong-lanceolate to narrowly deltate; indusia glandular or not; spores dark brown.	Athyrium filix-femina var. asplenioides