Leaves and stems:

Leaves (fronds) are evergreen, 1 to 15 inches long (typically less than 10) and to 3 inches wide, once or twice compound with 4 to 9 pair of leaflets (pinnae). Only the lower pinnae are twice compound or sometimes merely lobed in 2 or 3 segments. Pinnae and lobes are lance-oblong to linear, leathery, blue-green, the lower pinnae short-stalked, the upper pinnae stalkless.

Pinnae are hairless except sometimes for a few hairs on the underside near the midrib; veins are obscure. Stems are uniformly dark brown to purplish, slender, shiny, and smooth except for scattered hair-like scales. Plants grow spreading to sprawling in an asymmetrical clump, the withered remains often persisting to the next season. Fertile and sterile fronds are similar in size and shape.

Spores:

The sori (group of spores) develop on fertile fronds starting in early summer and are found on the underside of a leaflet along the edge, the leaflet edge rolled around them so most are unexposed.

Notes:

Smooth Cliff Brake is a fairly distinctive species, the only one really similar is the rare Purple Cliff Brake (Pellaea atropurpurea), found only in 4 counties in the southeast corner of the state. Purple Cliff Brake has rather larger pinnae, densely hairy/scaly stems, and typically grows erect, where Smooth Cliff Brake has—you guessed it—smooth stems, barring a few sparse hairs, and is more spreading/sprawling. Depending on the reference, there are up to 4 subspecies (or varieties) of P. glabella, distinguished mostly by the number of spores in a group (32 or 64—go ahead, count them) and the hairiness of the pinnae. The species is widespread in North America with the subspecies having more regional distributions; subsp. glabella is found in Minnesota and we are on the western edge of its range.