Plants 35-80(-120) cm tall. Rhizome long creeping, 1-1.5 cm in diam., apex with blackish brown scales; scales also at base of stipes. Fronds clustered, submonomorphic; stipe 15-55 × 1.5-3 cm, stipe and rachis castaneous-reddish, shiny, glabrous; lamina pinnate, oblong-lanceolate in outline, 15-40(-60) × 6-15(-18) cm, at one side deeply bipinnate-lobed; lateral pinnae 4-7 pairs, opposite or subalternate, spreading, basal pairs shortly stalked; upper ones sessile; lamina half-triangular and slightly falcate, 5-10(-18) × 4-7 cm, basiscopic side pectinately lobed nearly to costa, acroscopic side reduced to subentire wing to 6 mm wide, base oblique, basiscopic side decurrent, apex caudate-acuminate; basiscopic segments 3-6 or more, falcate-lanceolate, basal part longest, 1.5-4(-8.5) × 0.3-0.6(-1.1) cm, basally margins of sterile segments acutely serrate, fertile segments entire except for with 1 spine or 2 or 3 acute teeth near apex, apex mucronate or obtuse; terminal pinna pectinately divided almost to rachis, broadly lanceolate to narrowly triangular in outline, 10-18 × 3-10 cm, apex caudate; segments 6-12 pairs, opposite, spreading, 3-5 mm apart, falcate-lanceolate, 2.5-5 × 0.6-1 cm, upper ones gradually reduced, basiscopic obtriangular wing decrescent to next pair of pinnae along costule, apex shortly acuminate; costae prominent abaxially, chestnut adaxially, distally straw-colored, grooved adaxially, grooves with thin, minutely and irregularly toothed, raised edges. Veins conspicuous, decumbent, 2-forked or bipinnate-forked, veinlets reaching base of teeth; lamina gray-green, herbaceous when dried, glabrous. 2n = 116.

Pteris semipinnata is different from P. dispar in shape and distribution. The former is primarily distributed in tropical areas, while P. dispar is primarily distributed in subtropical and northern tropical areas. Both are in Fujian and Taiwan, but any intersecting types have not been seen.

Acidic soil in open forests, by streams or rocks; below ca. 900 m. Fujian, Guangdong, Guangxi, S Guizhou (Ceheng, Sandu), Hunan, S Jiangxi (Anyuan, Xunwu), Sichuan (Leshan), Taiwan, S Yunnan [Bhutan, N India, Indonesia (Borneo), Japan (Ryukyu Islands), Laos, Malaysia, Myanmar, Nepal, Philippines, Sri Lanka, Thailand, Vietnam].