Etymology Scopulinum means of the rocks. See section marked Culture.

Description Rhizome: erect, short, stout, scaly.
Frond: 40 cm high by 6 cm wide, evergreen, monomorphic, blade/stipe ratio: 2:1 to 4:1.
Stipe: grooved, densely scaly but scales falling off above, light brown, abruptly diminishing in size upward, vascular bundles: 4 or more, in an arc.
Blade: 1-pinnate-pinnatifid, but described also as merely 1-pinnate or in older specimen 2-pinnate, lanceolate, base narrowed, glossy, microscales narrowly lanceolate, sparse, on lower surface only, and falling soon.
Pinnae: 20 to 40 pair, oblong-lanceolate, 1--3 cm, basal lobes (the upper one larger, eared outward) cut to the costa, the remainder of the pinna more accurately described as serrate, anadromic; margins serrate, spiny, 8-25 spines on each edge of the pinna; veins free, forked.
Sori: round, touching at maturity, nearly covering the entire surface on the upper two-thirds of the frond, except for the basal lobes, in 1 row on both sides of the costa, indusium: peltate, central, sporangia: brown, maturity: late spring.
Dimensionality: pinnae folded inward and twisted horizontally.

Culture Habitat: rock crevices and at base of boulders, serpentine to acidic substrates, usually exposed to full sun . Distribution: British Columbia to Arizona, disjunct in Quebec, Newfoundland. Hardy to -30°C, USDA Zone 4.

Synonyms
Aspidium aculeatum (Linnaeus) Swartz var. scopulinum D. C. Eaton
Polystichum mohrioides (Bory) C. Presl var. scopulinum (D. C. Eaton) Fernald
Aetopteron scopulinum House