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.