1. Osmunda claytoniana Linnaeus, Sp. Pl. 2: 1066. 1753.
绒紫萁 rong zi qi
Osmunda claytoniana subsp. pilosa (Wallich ex Greville & Hooker) Fraser-Jenkins; O. claytoniana var. pilosa (Wallich ex Greville & Hooker) Ching; O. claytoniana subsp. vestita (Wallich ex Milde) Á. Löve & D. Löve; O. claytoniana var. vestita Wallich ex Milde; O. pilosa Wallich ex Greville & Hooker; Osmundastrum claytonianum (Linnaeus) Tagawa; O. claytonianum subsp. pilosum (Wallich ex Greville & Hooker) Tzvelev; O. claytonianum var. pilosum (Wallich ex Greville & Hooker) W. M. Chu & S. G. Lu.
Rhizome ascending, short, bearing several approximate fronds. Fronds hemidimorphic; stipe greenish, shorter than lamina, 15-20 cm, usually woolly; lamina pinnate-pinnatifid, narrowly oblanceolate, 30-40 × 15-25 cm, apex acute to acuminate; pinnae 20-30 pairs, fertile pinnae few, in lower middle portion of lamina; sterile pinnae linear-lanceolate, larger ones often more than 25 × 3.5 cm, incised more than 2/3 toward costa, apex acuminate; ultimate segments entire, naked at margin, or with grayish white to grayish brown hairs when young, apex rounded; fertile pinnae ca. 1/3 length of sterile ones, ca. 5 mm wide but usually with reduced lobes, covered throughout with sporangia, turning blackish brown after spores are shed. 2n = 44.
Forming large populations on hillsides; 1600-3400 m. Chongqing, Guizhou, Hubei, Hunan, Liaoning, Sichuan, Taiwan, Xizang, Yunnan [Bhutan, N India, Japan, Korea, Nepal, Russia (Far East); North America].