稀叶珠蕨 xi ye zhu jue

Pteris stelleri S. G. Gmelin, Novi Comment. Acad. Sci. Imp. Petrop. 12: 519. 1768; Allosorus gracilis (Michaux) C. Presl; A. stelleri (S. G. Gmelin) Ruprecht; Cheilanthes gracilis (Michaux) Kaulfuss; Pellaea gracilis (Michaux) Hooker; P. stelleri (S. G. Gmelin) Baker; Pteris gracilis Michaux.

Rhizomes slender, long creeping; scales light brown, lanceolate or ovate-lanceolate. Fronds scattered along rhizomes; stipe brownish straw-colored, glabrous, stipe of sterile frond 3-8 cm, that of fertile frond 6-12 cm. Sterile fronds: lamina yellowish green, ovate or ovate-oblong, 3-6 × 1.5-3 cm, 1- or 2-pinnate, herbaceous to membranous, glabrous on both surfaces, apex obtuse; hydathodes poorly developed or absent. Fertile fronds: lamina broadly lanceolate or oblong, 4-8 × 1.8-4 cm, 2-pinnate. Sterile pinnae 3 or 4 pairs, subrounded, margins entire or slightly undulate, apex obtuse. Fertile pinnae 4 or 5 pairs, shortly stalked or subsessile, basal pair largest, 1-pinnate. Pinnules 1 or 2 pairs, anadromous, broadly lanceolate, shortly stalked or sessile, base cuneate, apex acute or obtuse. Sori borne at vein tips, discrete, often confluent at maturity. False indusia pale green, membranous, margins somewhat irregular, not reaching to main vein.

Rock crevices in Abies or Rhododendron woodlands; 1700-4200 m. Gansu, Hebei, Qinghai, Shaanxi, Shanxi, Sichuan, Taiwan, Xinjiang, SE Xizang, NW Yunnan [Afghanistan, Bhutan, India, Japan, Kashmir, Nepal, Russia; North America].