Rhizome short-creeping, densely clothed with dark brown hairs. Fronds clustered, erect, undivided, 4–60 cm long, c. 0.5 mm wide, terete or subterete, furrowed on 1 side, with scattered hairs, smooth; sterile fronds similar to sporogenous fronds but much shorter; sporogenous heads 4-50 mm long, usually 5–12 times longer than wide (rarely 2.5–3 times in reduced alpine forms), narrowly triangular to linear-oblong, broadest at or near base, tapering distally, straight or slightly curved; segments 2–5 mm long, smooth, glabrous or with scattered hairs. Sporangia not mixed with hairs.
Rhizome up to 5 mm. diam., clad in glossy chestnut hairs. Stipes 5-35 cm. long, about 1 mm. diam., erect, strict to flexuous, unbranched. Lamina 1-2 cm. × 5 mm.; segs 10-20, 2-5 mm. long, close-set, secund, slightly incurved. Sporangia about 0·5 mm. diam.