Deparia acrostichoides is monomorphic (fertile and sterile
leaves are similar in appearance) with healthy fronds well in
excess of 50 cm long. Sori are clearly elongate and lie along
the veins on the lower leaf surfaces. It is similar in general
appearance to Athryium filix-femina from which it differs
in the presence of multicellular hairs on the blades, and grooves
on the upper surface of the midrib (costa) of each pinna which
fail to join with the groove on the rachis. Though apparently
not consistent throughout its range, the great majority of plants
I have seen have longer and more consistently straight sori than
A. filix-femina, whose sori are shorter and more likely
to curve across the adjacent vein. Some individuals of D. acrostichoides
are prominently pubescent and stand out dramatically in the field,
especially early in the summer. The common name is based on the
general silvery appearance of the undersurface of the blade when
sori and their indusia are abundant, a character which can be
striking in some live individuals, but is less pronounced in others.
Deparia acrostichoides was long known as Athyrium thelypteroides.
It ranges across the northeastern U.S. and eastern Canada, west
to Minnesota and Arkansas and south into northern Alabama. In
Wisconsin it is widely distributed, but far less common than the
similar Athyrium filix-femina.