Athyrium filix-femina is a relatively large fern of clumped growth form. Fertile and sterile fronds are similar and in healthy plants are often over 50 cm in length. The blades are broadest at about the middle and are 2-pinnate or 2-pinnatifid. Sori are elongate and at least some sori are hooked at the tip to lie over the adjacent vein.

Four varieties of A. filix-femina are recognized, but only variety angustum is known in our area. Some fern books have given variety angustum species status as Athyrium angustum. It ranges from Newfoundland to Saskatchewan, south to North Carolina, Missouri and Nebraska and is common throughout Wisconsin in a variety of forests.