Description from Flora of China
Athyrium dissectifolium Ching; A. iseanum Rosenstock f. angustisectum (Tagawa) Sa. Kurata; A. iseanum var. angustisectum Tagawa.
Rhizomes short, erect, apex densely clothed with brown, ovate-lanceolate scales. Fronds caespitose, up to 35-55 cm; stipe blackish brown, upward stramineous, 10-25 cm, ca. 2 mm in diam. at base, base similarly scaly, upward glabrate; lamina 2-pinnate, with finely pinnate pinnules, ovate-lanceolate, 25-35 × 12-18 cm, base ± rounded, apex long acuminate; pinnae 10-12 pairs, alternate, slightly ascending, stalked (stalk 2-4 mm), lanceolate, middle pinnae up to 10 × ca. 3 cm at base, base subrounded-cuneate, pinnate-pinnatifid, apex acuminate; pinnules 10-12 pairs; basal pinnules of middle pinnae anadromous, alternate, subspreading, subsessile, broadly lanceolate; middle pinnules ca. 2 cm × 7 mm at base, base inequilateral, narrowly cuneate on basiscopic side, pinnatipartite nearly to costule, apex obtuse; pinnule segments ca. 4 pairs, ovate-lanceolate, ca. 5 × 2 mm, margin biserrate, apex obtuse. Veins inconspicuous adaxially, visible abaxially, pinnate in segments, lateral veins 3-5 pairs, oblique, forked or simple. Lamina thinly herbaceous when dried, brownish green, glabrate on both surfaces; rachis and costae abaxially stramineous, subbasal part of costae with dense short glandular hairs, with needlelike spines on adaxial side at base of costa, costule, or midrib. Sori oblong or orbicular-reniform, lateral on acroscopic veins, 1-4 sori per segment; indusia brown, oblong or orbicular-reniform, membranous, erose at margin, persistent. Perispore surface without folds. 2n = 80, 160.
Valley forests, wet areas, Tsuga forests or high-elevation bamboo grasslands; (600-)1500-3000 m. Guangxi, Guizhou, Hubei, Hunan, Taiwan, Zhejiang [Japan].