11. Polypodiodes amoena (Wallich ex Mettenius) Ching, Acta Phytotax. Sin. 16(4): 27. 1978.
友水龙骨 you shui long gu
Rhizome 5-7 mm in diam., densely covered with scales; scales dark-brown, lanceolate, base broad, margin denticulate, apex acuminate. Stipe straw-colored or castaneous, (5-)30-40 cm, glabrous. Lamina pinnatisect, ovate-lanceolate in outline, (11-)40-50 × (4-)20-25 cm, base slightly narrowed, apex acuminate. Segments 20-25 pairs, lanceolate, 10-13 × 1.5-2 cm, connected along rachis by a 1.5-4 mm wide wing, margin shallowly crenate to subserrate, apex acuminate; basal 1 or 2 pairs of segments often deflexed. Veins forming 1 or 2 rows of areoles along each side of rachis and costa. Lamina thickly papery, green, both surfaces glabrous or pubescent, abaxial surface scaly. Sori orbicular, medial.
Epiphytic on rocks or on tree trunks; 1000-2500 m. Anhui, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Jiangxi, Shanxi, Sichuan, Taiwan, Xizang, Yunnan, Zhejiang [Bhutan, India, Laos, Myanmar, Nepal, Thailand, Vietnam].
The collection Purdom 32 (Tai-pei-shan) was identified by R. C. Ching as a dwarf "northern form" of Polypodiodes amoena. It has fronds with the stipe ca. 5 cm, lamina ca. 11 × 4 cm, and ca. 16 pairs of segments with obtuse apices.
Polypodium daochengense Ching & S. K. Wu (Acta Phytotax. Sin. 31: 574. 1993), described from Sichuan, was compared in the protologue to P. amoenum (Polypodiodes amoena), where it was differentiated primarily by its smaller size.
