The fronds of Woodsia oregana are 4-25 cm long and the
blades are pinnate-pinnatifid or 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 reddish brown to dark purple , hydathodes on the blade segments
are inconspicuous, and the indusia are divided into numerous very
narrow, filamentous segments. The similar W. obtusa has
petioles for which the proximal (lower) portion of the petiole
is light brown or straw-colored, there are conspicuous hydathodes
on the adaxial surface of the blade segments, and the indusia
are divided into numerous relatively broad segments.
Two subspecies of Woodsia oregana have been identified,
but only variety cathcartiana occurs in Wisconsin. It ranges
from California to Saskatchewan, east to Oklahoma and Michigan.
In Wisconsin it is a "special concern" species reported
from several locations in Vernon and Lacrosse Counties and from
one site each in Douglas, Iron, Polk, Iowa and Richland Counties.
Habitat throughout its range is usually on rocks, both acidic