Description from Flora of China
Rhizomes long creeping; scales brown or reddish brown, lanceolate. Fronds monomorphic, widely spaced. Stipe 10-28 cm, straw-colored above a dark brown base. Lamina elliptic, 24-28 × ca. 15 cm, base cuneate, apex acuminate, 3-pinnate-pinnatifid to 4-pinnate, thinly papery to papery when dry, dark green, not farinose. Lateral pinnae 8-10 pairs, alternate, crowded, basal pair similar to but larger than adjacent pinnae, elliptic, 13-16 × 3-5 cm, stalked to ca. 1 cm, base cuneate, apex caudate. Ultimate sterile pinnules (segments) similar to but shorter than fertile ones. Ultimate fertile pinnules (segments) not overlapping, linear to elliptic-lanceolate, 5-7(-10) × ca. 1 mm, apex acuminate. Sori restricted to median portions of ultimate fertile pinnules (segments), 2-5 mm. False indusia oblong to narrowly oblong, extending nearly to midvein, entire.
Onychium tibeticum is similar to O. cryptogrammoides but differs in having a brown stipe base, caudate pinna apices, and longer ultimate segments. However, some botanists consider it to represent a mere variant of O. japonicum that was described based on a specimen with the frond intermediate between sterile and fertile morphologies.
● Banks of ditches under trees; 2000-2300 m. Xizang.