Aspidium caespitosum Wallich ex Mettenius var. stenophyllum Franchet, Pl. David. 2: 155. 1888; Polystichum conaense Ching & S. K. Wu; P. deversum Christ; P. niitakayamense Hayata; P. pseudostenophyllum Tagawa; P. stenophyllum var. abbreviatum Tagawa; P. stenophyllum var. conaense (Ching & S. K. Wu) W. M. Chu & Z. R. He.

Plants evergreen. Rhizome erect, short, densely covered with thin scales; scales brown, lanceolate, margins ciliate. Fronds 15-60 cm; stipe stramineous or light purplish red, 1-12 cm, 1-2 mm in diam. at base, often densely covered with thin scales; scales large or small; large scales ovate, up to 8 × 5 mm, entire, shortly acuminate; small scales ovate-lanceolate, up to 4 × ca. 1 mm, margins fimbriate, apex long acuminate. Lamina pinnate, linear-lanceolate, 8-50 × 1-5 cm at middle, below middle gradually contracted toward base; rachis stramineous or light purplish red, densely scaly on both surfaces; scales similar to small scales on stipe; rachis with 1 proliferous bulbil near tip. Pinnae 20-60 pairs, alternate, approximate or slightly imbricate, falcate-oblong, middle pinnae larger, 0.5-2.5 cm × 3-10 mm, margins serrulate, apices acute and shortly spinulose; acroscopic bases auriculate, auricles deltoid with spinulose tip, adaxial lateral side truncate, parallel to rachis, basiscopic base cuneate, margins shortly spinulose-serrulate or eroded, pinnae gradually contracted toward base below middle part, ± reflexed toward lamina base; adaxially subglabrous, abaxially densely covered with brownish microscales; microscales peltate, ovate-lanceolate, sparsely toothed; frond texture thickly papery; venation pinnate, distinct or nearly indistinct abaxially, concave adaxially; lateral veins ascendant, nearly reaching pinna margin; acroscopic veinlets pinnate, forked or free from base to upper part; basiscopic veinlets often forked, sometimes basiscopic forked veinlets at middle forked again. Sori terminal on veinlets of pinnae, in 1 row on each side of midrib, medial or submedial between midrib and pinna margin; indusia present, brown or dark brown, subentire, often persistent.

Sometimes the pinna margins of Polystichum stenophyllum can be roughly serrate or pinnatilobate and the inner side of basal acroscopic auricles can be pinnatilobate to pinnatifid toward base (P. stenophyllum var. conaense). Some authors treat P. pseudostenophyllum separately (e.g., Knapp, Ferns Fern Allies Taiwan, 203, 474. 2011).

Polystichum stenophyllum has been placed in P. sect. Polystichum by Fraser-Jenkins (Himalayan Ferns (Guide to Polystichum), 7. 1997).

Montane broad-leaved forests, mixed broad-leaved and coniferous forests, bamboo forests; 1700-3500 m. S Gansu, SW Henan, W Hubei, W Sichuan, Taiwan, Xizang, NE and NW Yunnan [Bhutan, India, Japan, N Myanmar, C Nepal].