Pellaea atropurpurea fronds are often relatively small with blades 5-25 cm long. The blade is pinnate toward the tip and 1- or 2-pinnate at the base. Sporangia are borne under the inrolled margins of the blade segments. The red/purple rachis is densely pubescent on the adaxial (upper) surface, unlike the glabrous adaxial surface of the similar P. glabella.

P. atropurpurea ranges from southern Quebec to Florida west to Wisconsin, South Dakota, Colorado and Nevada. In Wisconsin it is rare, listed as a "special concern" species and is known only from the southwestern counties. Many of the records are near the Wisconsin River. It grows primarily on limestone.