Description from Flora of China
Nephrodium subtriangulare C. Hope, J. Bot. 28: 327. 1890; Dryopteris acutidens Ching (1959), not C. Christensen (1905); D. caudifrons Ching; D. subassamensis Ching; D. uropinna Price; Lastrea filix-mas (Linnaeus) C. Presl var. subtriangularis (C. Hope) Beddome.
Rhizome ascending, 2-2.5 cm in diam., covered with scales at apex. Fronds caespitose. Stipes stramineous, 20-30 cm, 1-1.5 mm in diam., base dark brown and densely covered with scales; scales black or blackish brown, linear-lanceolate; scales upward smaller or subglabrous. Lamina deltoid-lanceolate, 30-35 × 20-25 cm, widest at base, bipinnate, with a somewhat caudate apex. Pinnae 5-7 pairs, broadly lanceolate; basal pinnae largest, up to 12-13 × 4-5 cm, stalked, other pinnae sessile. Pinnules distinct on lower part of lamina, usually 4-6 pairs on each pinna, oblong; pinnules on basiscopic side of lowest pinnae larger than those on acroscopic side, ca. 3 × 1 cm, truncate at base, pinnatifid, obtuse and toothed at apex. Veins pinnate; veinlets simple or forked, visible abaxially. Lamina herbaceous, dark green, glabrous adaxially, scaly abaxially; rachis subglabrous; pinna rachis and costa covered with bullate, brown scales. Sori orbicular, medial; indusia brown, reniform, entire.
Tropical, subtropical, or warm-temperate forests; 500-1500 m (in Taiwan). Guangxi, Guizhou, Hainan, Sichuan, Taiwan, Xizang, Yunnan [India, Myanmar, Philippines, Thailand, Vietnam].