Acrostichum ilvense Linnaeus, Sp. Pl. 2: 1071. 1753; Nephrodium rufidulum Michaux; Polypodium ilvense (Linnaeus) Villars; Woodsia rufidula (Michaux) L. C. Beck.

Plants 12-17 cm tall. Rhizomes erect or ascending, scaly; scales concolorous, brown, broadly lanceolate, ca. 4 mm, membranous, margin entire. Fronds clustered; stipe castaneous, lustrous, 3-7 cm, ca. 1 mm in diam., with long hairs and linear-lanceolate scales, articulate below middle; lamina 1-pinnate-pinnatifid, lanceolate, 8-11 × 1.3-2 cm, herbaceous, covered with articulate hairs, especially abaxially, base gradually attenuate, apex acuminate; rachis and costae with brown, linear scales and long articulate hairs; pinnae 10-20 pairs, sessile, well separated, oblique; middle pinnae largest, ovate-lanceolate, 8-11 × 4-8 mm, pinnatifid, with 3-5 pairs of lobes, apex acute; pinna lobes elliptic, basal pair largest, 2-4 mm, entire or irregularly undulate. Veins pinnate, veinlets not reaching laminar margin. Sori orbicular and attached at ends of veinlets, submarginal; indusia saucer-shaped, membranous, margin long ciliate. 2n = 78(82).

Cliffs, rocky slopes; 200-2200 m. Hebei, Heilongjiang, Jilin, Nei Mongol, Xinjiang [Kazakhstan, Mongolia, Russia; Europe, North America].