Leaves and stems:

Leaves (fronds) are evergreen, up to 20 inches long and to 7 inches wide, once or twice compound with 5 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 on the underside along the midrib; veins are obscure. Pinnae edges are whitish and a bit wavy. Pinnae of fertile fronds are typically rotated and held parallel to the ground.

Stems are uniformly dark brown to purplish, slender, shiny, and densely covered in reddish brown to tan, curly, hair-like scales. Plants grow in an asymmetrical clump, are often erect, and the withered remains often persist to the next season. Fertile fronds are usually somewhat larger and more divided than sterile fronds.

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.

Notes:

A rare fern in Minnesota, Purple Cliff Brake is known only from fewer than 20 locations in 4 southeast counties. According to the DNR, it is found on steep, open, south-facing bluff prairies, which are at risk of degradation and even destruction primarily due to land management practices, particularly habitat fragmentation, fire suppression, and the encroachment of woody plants and invasive species. It was listed as a Special Concern species in 1984. It is not likely to be confused with any other fern except Smooth Cliff Brake (Pellaea glabella), which is similar in most respects except the fronds are smaller, the stem is smooth except for a few scattered hairs, and is more often found on vertical cliffs and fissures in rock faces.