The fronds of Woodsia obtusa are 8-60 cm long and the
blades are often 2-pinnate, at least at the base. The blades are
glandular. The stems lack the jointed stipe of W. ilvensis.
The proximal (lower) portion of the petiole is light brown or
straw-colored and there are conspicuous
hydathodes on the adaxial surface of the blade segments. The
indusia are divided into numerous relatively broad segments. The
similar W. oregana has petioles for which the proximal
(lower) portion of petiole is reddish brown to dark purple, hydathodes
are inconspicuous, and the indusia are divided into numerous very
narrow, filamentous segments.
Two subspecies of Woodsia obtusa have been identified,
but only subspecies obtusa occurs in Wisconsin. It ranges
from Quebec to Florida, west to eastern Texas and southeastern
Minnesota. In Wisconsin it is found mostly in the southwestern
counties. It grows on a variety of rocks.