Lomaria adnata Blume, Enum. Pl. Javae 2: 205. 1828; L. brooksii Alderwerelt; Plagiogyria adnata var. condensata Christ; P. adnata var. reflexa C. Christensen & Tardieu; P. adnata var. yakushimensis (K. Satô) K. Iwatsuki; P. distinctissima Ching; P. meghalayensis R. D. Dixit & A. Das; P. rankanensis Hayata; P. rankanensis var. yakushimensis (K. Satô) Nakaike; P. subadnata Ching; P. wulingshanensis C. M. Zhang & S. F. Wu; P. yakumonticola Nakaike; P. yakushimensis K. Satô; P. yunnanensis Ching; Struthiopteris brooksii (Alderwerelt) Ching.

Stipes (4.5-)15-25(-35) cm on sterile fronds, (17-)40-50(-65) cm on fertile fronds, distally tetragonal or rarely triangular in cross section; vascular bundle V-shaped; stipes and rachises glabrous; aerophores cushionlike, present only on stipe base. Sterile lamina pinnatifid, (8-)15-25(-36) × (3-)5-15(-26) cm, not glaucous, apex confluent, terminating in a pinnatilobed segment; rachises abaxially semiterete to trigonous; pinnae (8-)13-20(-35) pairs; proximal pinnae adnate to rachises, not deflexed to subdeflexed, not abbreviated or slightly shortened; middle pinnae acroscopically adnate to rachises, basiscopically rounded; distal pinnae subequilaterally adnate to rachises, basiscopically decurrent; veins mostly paired at base, forked above base, or rarely simple. Fertile lamina pinnate, (8-)16-26(-45) × (2-)4-10(-16) cm; rachises abaxially flattened or grooved; pinnae (9-)13-17(-24) pairs, sessile or shortly stalked; proximal pinnae shortly stalked, not abbreviated. Paraphyses many or few, rarely shed early, yellow or brown. Spores yellow, with reddish tubercles. 2n = 260.

Plagiogyria japonica and P. adnata hybridize. Specimens of P. japonica with acroscopically adnate pinnae may key out to P. adnata. Fronds of P. japonica usually end in a segment similar to a short lateral pinna, while fronds of P. adnata have pinnatifid apices.

Forests, wet areas, mountain slopes; near sea level to 2000 m, common above 500 m. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hubei, Hunan, Jiangxi, Sichuan, Taiwan, Yunnan, Zhejiang [E and N India, Indonesia (Java, Sumatra), Japan, Malaysia (including Borneo), Myanmar, Philippines (Luzon), Thailand, Vietnam].