日本水龙骨 ri ben shui long gu

Polypodium niponicum Mettenius, Ann. Mus. Bot. Lugduno-Batavi 2: 222. 1866; Goniophlebium niponicum (Mettenius) Beddome; Marginaria niponica (Mettenius) Nakai ex H. Itô; M. transpianensis (Yamamoto) H. Itô; Polypodiodes transpianensis (Yamamoto) Saiki; Polypodium bodinieri Christ; P. longkyense Rosenstock; P. silvestrii Christ; P. transpianense Yamamoto.

Rhizome long creeping, gray-green, ca. 5 mm in diam., sparsely covered with whitish bloom and scales; scales dark brown, narrowly lanceolate with ovate base, margin denticulate, apex acuminate. Stipe straw-colored, 5-15 cm, pubescent. Lamina oblong-lanceolate, 30-40 × 10-13 cm, pinnatipartite, cordate at base, pinnatilobate-acuminate at apex. Segments 15-25 pairs, linear-oblong, 3-5 × 0.5-1 cm, entire at margin, acute or obtuse at apex; lowest ones often subfree, slightly shortened and deflexed. Veins anastomosing to form 1 row of areoles at each side of rachis and each side of costa, veinlets invisible. Lamina herbaceous, gray-green, pubescent on both surfaces or more densely so abaxially with short, whitish, 2- or 3-celled, soft hairs. Sori orbicular, in 1 row on each side of costa, terminal on included veinlets in costal areoles, nearer to costa than to margin.

Epiphytic on tree trunks or on rocks; 300-1800 m. Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Jiangsu, Jiangxi, Shanxi, Sichuan, Taiwan, Xizang, Yunnan, Zhejiang [NE India, Japan, Vietnam].

Material of Polypodiodes niponica from Taiwan with the rhizomes lacking the whitish bloom and with very narrow scales has been separated as P. transpianensis.

The authors have not seen material of Polypodiodes niponica var. glandulosa P. S. Wang (Pterid. Fl. Guizhou, 517. 2001).