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 and basic.