29. Pyrrosia davidii (Giesenhagen ex Diels) Ching, Acta Phytotax. Sin. 10: 301. 1965.
华北石韦 hua bei shi wei
Niphobolus davidii Giesenhagen ex Diels, Nat. Pflanzenfam. 1(4): 325. 1899, based on Polypodium davidii Baker, Ann. Bot. (Oxford) 5: 472. 1891, not Franchet (1887); Cyclophorus davidii (Giesenhagen ex Diels) H. Léveillé; C. gralla (Giesenhagen) C. Christensen; C. matsudai Hayata; C. pekinensis C. Christensen, nom. illeg. superfl.; C. pekinensis f. minor C. Christensen; C. subfissus Hayata; C. transmorrisonensis Hayata; Niphobolus gralla Giesenhagen; Pyrrosia gralla (Giesenhagen) Ching; P. matsudai (Hayata) Tagawa; P. nudicaulis Ching; P. pekinensis (C. Christensen) Ching, nom. illeg. superfl.; P. subfissa (Hayata) Ching; P. transmorrisonensis (Hayata) Ching.
Plants 5-20 cm tall. Rhizome shortly elongated, 1.6-3.1 mm in diam., in cross section with few to many sclerenchyma strands; phyllopodia 0.3-0.7 cm apart, lateral buds alternating with phyllopodia. Scales peltate, 1.4-6.8 × 0.5-2.1 mm, base entire to ciliate; acumen light brown to dull blackish with a distinct lighter margin, ciliate to dentate. Fronds monomorphic, not or indistinctly up to 5 cm stipitate; lamina widest above middle, 3-15 × 0.5-1.5(-2) cm, base gradually narrowed, apex acute to acuminate. Hydathodes distinct, superficial. Indument persistent, nearly or completely monomorphic, sparse to dense, hairs 0.2-1.6 mm in diam. Sori superficial, without central bundle of paraphyses. Sporangia with stalks up to as long as capsule.
● On tree trunks in forests, on shaded and wet rocks of slopes; 200-3400 m. Gansu, Guizhou, Hebei, Henan, Hubei, Hunan, Liaoning, Nei Mongol, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Xizang, Yunnan.
The name Pyrrosia davidii is sometimes restricted to small forms with an appressed indument from the northern part of the range (Shing & Iwatsuki, J. Jap. Bot. 72: 2. 1997), but there is no sharp distinction between these and larger forms. Pyrrosia davidii is closely related to P. porosa and might be better treated as a synonym of P. porosa var. porosa, representing forms with an almost monomorphic indument.