Stems decumbent to erect, much branched from base, stout, 4–8 mm diam. (including hardened, persistent leaf bases); scales often bicolored, dense, broadly lanceolate to linear, to 6 × 2 mm. Leaves strongly tufted, deciduous; sterile leaves spreading, 3–20 cm; fertile leaves erect, 5–25 cm; petioles, costae, and costules glabrous. Petiole green to straw-colored, dark brown only on proximal 1/8 or less, ca. 1 mm wide when dry, collapsing and strongly furrowed; scales bicolored or ± concolored, becoming sparse distally. Blade deltate to ovate-lanceolate, all 2–3-pinnate, herbaceous, thin and translucent when dried, hydathodes superficial. Segments of sterile leaves oblong to fan-shaped, bases cuneate, distal 1/2–1/3 of each segment regularly dentate and often more deeply incised every 2d and 4th tooth; segments of fertile leaves ascending to erect, strongly differentiated from those of sterile leaves, linear, 3–12 × 1–2 mm; fertile segments revolute, covering sporangia. Sporangia in sori that coalesce at maturity. 2n = 60.
Habitat: New growth produced in spring, spores maturing in late summer and autumn, leaves dying in autumn. Talus slopes and cliff crevices, often on igneous rocks, typically in relatively mesic subalpine habitats
Elevation: 900–3500 m
B.C., Calif., Idaho, Mont., Oreg., Wash.
Populations of Cryptogramma cascadensis were previously identified as C. acrostichoides.