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.