Description from Flora of China
Plants epiphytic or epilithic, small to medium-sized. Rhizome long creeping, covered with scales; scales brown, lanceolate or narrowly lanceolate, clathrate or centrally clathrate. Fronds usually remote, articulate at base, monomorphic. Lamina broadly lanceolate, simple, pinnatifid, truncate at base, pinnatilobed at apex. Lateral segments more than 5 pairs, lanceolate, ± falcate, entire to incised at margins. Veins free, veinlets forked. Sori orbicular, in 1 row on either side of costa, borne on acroscopic branch of a free forked veinlet; sporangia long stalked, annulus with ca. 20 hardened cells. Spores yellow, ellipsoid, surface verrucate. x = 37.
Ten uncertain taxa, not included in the following key, are listed at the end of the account.
- Polypodium grandiceps G. Nicholson (Ill. Dict. Gard. 4: 592. 1888), described from Taiwan.
- Polypodium griseonigrum Baker (Bull. Misc. Inform. Kew 1895: 55. 1895 [“griseo-nigrum”]), described from Yunnan.
- Polypodium lobatum Hudson var. hupehense Pampanini (Nuovo Giorn. Bot. Ital., n.s., 22: 252. 1915), described from Hubei.
- Polypodium mathewii Tutcher (J. Linn. Soc., Bot. 37. 68. 1905), described from Shandong.
- Polypodium micropteris Baker (Bull. Misc. Inform. Kew 1906: 14. 1906), not C. Christensen (1905), described from Yunnan.
- Polypodium muliense Ching ex K. H. Shing (Acta Phytotax. Sin. 31: 573. 1993), described from Sichuan.
- Polypodium nervopilosum K. H. Shing (Acta Phytotax. Sin. 31: 573. 1993), described from Sichuan.
- Polypodium obtusifrons Hayata (Icon. Pl. Formosan. 4: 250. 1914), described from Taiwan.
- Polypodium rosthornii Diels (Bot. Jahrb. Syst. 29(2): 205. 1900), described from China (“Kin-shan”).
- Polypodium trichophyllum Baker (Bull. Misc. Inform. Kew 1906: 13. 1906), described from Yunnan.
About ten species: throughout the N temperate zone, ranging from temperate Europe and N Asia to North America; two species in China.
(Authors: Lu Shugang (陆树刚); Christopher Haufler)